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2. Extracting microphysical fault friction parameters from laboratory and field injection experiments

Author

M. P. A. van den Ende, M. M. Scuderi, F. Cappa, and J.-P. Ampuero

Subjects
Geology, QE1-996.5, Stratigraphy, QE640-699
Abstract

Human subsurface activities induce significant hazard by (re-)activating slip on faults, which are ubiquitous in geological reservoirs. Laboratory and field (decametric-scale) fluid injection experiments provide insights into the response of faults subjected to fluid pressure perturbations, but assessing the long-term stability of fault slip remains challenging. Numerical models offer means to investigate a range of fluid injection scenarios and fault zone complexities and require frictional parameters (and their uncertainties) constrained by experiments as an input. In this contribution, we propose a robust approach to extract relevant microphysical parameters that govern the deformation behaviour of laboratory samples. We apply this Bayesian approach to the fluid injection experiment of Cappa et al. (2019) and examine the uncertainties and trade-offs between parameters. We then continue to analyse the field injection experiment reported by Cappa et al. (2019), from which we conclude that the fault-normal displacement is much larger than expected from the adopted microphysical model (the Chen–Niemeijer–Spiers model), indicating that fault structure and poro-elastic effects dominate the observed signal. This demonstrates the importance of using a microphysical model with physically meaningful constitutive parameters, as it clearly delineates scenarios where additional mechanisms need to be considered.

Published
2020
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3. Slow-to-fast transition of giant creeping rockslides modulated by undrained loading in basal shear zones

Author

Federico Agliardi, Marco M. Scuderi, Nicoletta Fusi, and Cristiano Collettini

Subjects
Science
Abstract

Giant rockslides creep slowly for centuries and then can fail catastrophically, posing major threats to society. Here, the authors use observational and experimental evidence to quantitatively capture the full spectrum of giant rockslide behaviour until collapse, that is modulated by hydro-mechanical response to short-term fluid pressure perturbations.

Published
2020
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4. Mechanical characterization and properties of continuous wave laser irradiated Ge2Sb2Te5 stripes

Author

G. D'Arrigo, M. Scuderi, A. Mio, G. Favarò, M. Conte, A. Sciuto, M. Buscema, G. Li-Destri, E. Carria, D. Mello, M. Calabretta, A. Sitta, J. Pries, and E. Rimini

Subjects
GST, Continuous wave laser irradiation, Ultra nano-indentation, GST mechanical properties, Materials of engineering and construction. Mechanics of materials, TA401-492
Abstract

Crystalline micrometer size stripes in 2.2 μm thick Ge2Sb2Te5 phase-change material films were produced by irradiation with a Continuous Wave Laser of 405 nm wavelength. The shape and the dimensions of the crystallized regions were investigated by Transmission Electron Microscopy and then compared with simulations based on temperature-crystal growth velocity literature data. The temperature-time profile was determined taking into account the laser power, the optical and thermal properties of both the amorphous and crystalline phase. The mechanical properties of the amorphous and of the crystallized regions were characterized by an ultra nano-indentation technique. This procedure allows a direct and local measurement of hardness and Young's modulus in the amorphous and in the contiguous crystalline regions on the micrometer scale. The following values for Young's modulus and for hardness were obtained: 33±4 GPa and 2.00±0.3 GPa for the amorphous phase, and 51±8 GPa and 2.90±0.45 GPa for the crystalline phase. The stresses induced by the density increase in the crystallized region cause, on the irradiated surface, a series of fracture whose characteristic behavior depends on the laser power and on the spacing between two contiguous scans. These results are of relevance for the mechanical failure mechanisms in potential phase-change devices.

Published
2021
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5. Robotic enucleation of a solid pseudopapillary neoplasm in a 9-year-old girl

Author

G. Spampinato, A. Pasqualetto, E. Santonocito, M. Palermo, G. Belfiore, A. Basile, A. Di Cataldo, V. Di Benedetto, and M. Scuderi

Subjects
gruber-frantz tumor, pancreatic tumor, tru-cut biopsy, robotic surgery, tumor enucleation, solid pseudopapillary tumor, Neoplasms. Tumors. Oncology. Including cancer and carcinogens, RC254-282
Abstract

Objective: Here we reported the case of a 9-year-old girl with no relevant past medical or surgical history. Solid pseudopapillary neoplasms (SPN) is a rare pancreatic tumor, which is often observed in females in their second or third decades, but it can also be found in pediatric age. It is considered a low-grade malignant epithelial neoplasm with low metastatic rate and surgical resection represents the treatment of choice with an excellent long-term prognosis. Case report: A 9-year-old girl presented at our Emergency Department with a three days history of vomiting and vague abdominal pain. US showed an epi-mesogastric solid mass of 8 cm, diagnosis confirmed by the CT scan. A US-guided Tru-cut biopsy was performed obtaining the histologic diagnosis of Solid pseudopapillary neoplasm (Gruber-Frantz tumor). A Robotic enucleation of the neoplasm was performed, and histopathology confirmed an SPN with complete resection. In the case of low-malignant neoplasms like SPNs, enucleation, when feasible, represents the best surgical approach. Robotic procedures offer some technical and oncological advantages over minimally invasive techniques due to the stability of the operative field, the 3D and magnified vision and the articulated robotic arms. Conclusions: Robotic enucleation of solid pseudopapillary pancreatic tumors, when feasible, represents an excellent minimally invasive technique with a favorable long-term prognosis.

Published
2020
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6. Frictional stability and hydromechanical coupling of serpentinite-bearing fault gouge

Author

Marco M Scuderi and Brett M Carpenter

Subjects
Geophysics, Geochemistry and Petrology
Abstract

SUMMARY Observations of slow earthquakes and tremor have raised fundamental questions about the physics of quasi-dynamic rupture and the underlying fault zone processes. The presence of serpentinite at P-T conditions characteristic of deep tremor and slow earthquakes suggests that it plays an important role in controlling complex fault slip behaviour. Here, we report on experiments designed to investigate the frictional behaviour of serpentinite sampled from outcrop exposures (SO1 and SO2) of altered ultramafic rocks present at depth, and recovered from the SAFOD borehole (G27). XRD analyses reveal the presence of chrisotyle, lizardite, kaolinite, talc in SO1; lizardite, clinochlore and magnetite in SO2; and lizardite, quartz and calcite in G27. We sheared fault gouge in a double-direct shear configuration using a true triaxial deformation apparatus. The effective normal stress was varied from 2 to 40 MPa. We conducted velocity stepping tests and slide-hold-slide (SHS) tests in each experiment to characterize frictional stability and healing. At the end of each experiment, post-shear permeability was measured and the samples were recovered for microstructural analysis. The steady-state friction coefficient was μ = 0.17 for SO1, μ = 0.33 for SO2 and μ = 0.53 for G27. Overall, the gouges exhibit velocity strengthening behaviour, and become nearly velocity neutral at 40 MPa effective normal stress. SHS tests show positive healing rates for SO2 and G27, whereas SO1 exhibits zero or negative healing rates. Permeability decreases with increasing σn’, with SO1 (k = 10–20 m2) showing the lowest values. Microstructural observations reveal a well-developed R-Y-P fabric in SO1, which is not observed in SO2 and G27. We posit that the development of shear fabric controlled by mineralogy governs frictional and hydrological properties. In this context, when serpentinite is associated with other weak phyllosilicate minerals, frictional stability and hydrological properties can vary greatly, with a potential control on the mode of fault failure.

Published
2022
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7. Fault stability transition with slip and wear production: laboratory constraints

Author

Corentin Noël, Carolina Giorgetti, Marco M. Scuderi, Cristiano Collettini, and Chris Marone

Abstract

Large earthquakes take place on mature faults with hundreds of meters to kilometres of cumulative slip. At shallow depths, the fault zone is generally composed of non-cohesive rock wear products, often referred to as gouge. Seismic and aseismic slip occur in this fault gouge and fracture/brecciation of the wall rock and damage zone can add to the fault gouge as part of the wear process. Gouge thickness generally increases linearly with the cumulative fault shear displacement and laboratory work shows that gouge tends to stabilize fault frictional stability. Previous works show that frictional stability of simulated fault gouge varies as a function of shear displacement. The stability evolution is interpreted as a consequence of the degree of shear localisation within the simulated fault gouge: the more the deformation is localized, the more the fault slip is unstable. This implies that for bare rock surfaces, unstable behaviour is expected as the deformations are forced to be localized at the interface between the two sheared surfaces.On natural faults at large shear displacement (or for faults having a high gouge production rate), a competition must take place between 1) the localization of the deformation at rock-on-rock surfaces, 2) the delocalization of deformation due to gouge production and wall rock brecciation, 3) fault zone lithification and frictional healing and 4) shear localization within the gouge and wear material. The competition and interaction between these phenomena are modulated by cumulative fault slip, temperature and fluid chemistry. In turn, this competition may influence the frictional stability of faults with increasing shear displacement, and thus, their potential seismic activity.To characterise the influence of shear displacement on fault stability, constant velocity and velocity step experiments were performed to large displacement. Two initially intact rocks were chosen as starting material: a high porosity Fontainebleau sandstone and a low porosity quartzite. These samples represent very different resistances to abrasion (i.e., wear production with slip) for the same initial mineral composition (< 95% quartz), which allows us to investigate wear and wear rate on fault stability. Additionally, simulated quartz gouge was tested for comparison. Mechanical data are analysed within the rate-and-state framework, and post-mortem microscopic analyses of the sample were performed. For initially bare surface experiments a threshold shear displacement is required to transition from stable to unstable sliding. Stick-slip events (laboratory earthquakes) evolve systematically as a function of fault zone shear displacement. The inversion of the rate-and-state parameters shows that shear displacement has a dominant influence on both (a-b) and Dc. For all the faults tested, (a-b) decreases with increasing shear displacement. For high wear rates and simulated gouge, Dc decreases with increasing shear displacement. However, for low wear rate faults, Dc is constant within the tested shear displacement. These results demonstrate that, under the tested boundary conditions, fault stability varies systematically with fault maturity and in particular that shear displacement and strain localization are the dominant parameters controlling fault slip stability.

Published
2023
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9. Laboratory observations of slow earthquakes and the spectrum of tectonic fault slip modes

Author

J. R. Leeman, D. M. Saffer, M. M. Scuderi, and C. Marone

Subjects
Science
Abstract

Slow earthquakes, where fault slip is slow, can be large and may help trigger regular earthquakes, but the mechanics of slow slip are not fully understood. Leeman et al.show through laboratory experiments that slow slip behaviour on faults is controlled by the frictional dynamics of the surrounding material.

Published
2016
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13. Slow-to-fast transition of giant creeping rockslides modulated by undrained loading in basal shear zones

Author

Marco M. Scuderi, Nicoletta Fusi, Federico Agliardi, Cristiano Collettini, Agliardi, F, Scuderi, M, Fusi, N, and Collettini, C

Subjects
Dilatant, 010504 meteorology & atmospheric sciences, Science, friction, General Physics and Astronomy, Poison control, Pore fluid pressure, 010502 geochemistry & geophysics, 01 natural sciences, Article, General Biochemistry, Genetics and Molecular Biology, GEO/05 - GEOLOGIA APPLICATA, Pore water pressure, medicine, Geotechnical engineering, Rockslide, shear zone, laboratory experiment, lcsh:Science, Collapse (medical), landslaides, fluid, 0105 earth and related environmental sciences, Multidisciplinary, Natural hazards, Geomorphology, General Chemistry, Rockslide, Geophysics, Creep, 13. Climate action, lcsh:Q, medicine.symptom, Shear zone, Geology
Abstract

Giant rockslides are widespread and sensitive to hydrological forcing, especially in climate change scenarios. They creep slowly for centuries and then can fail catastrophically posing major threats to society. However, the mechanisms regulating the slow-to-fast transition toward their catastrophic collapse remain elusive. We couple laboratory experiments on natural rockslide shear zone material and in situ observations to provide a scale-independent demonstration that short-term pore fluid pressure variations originate a full spectrum of creep styles, modulated by slip-induced undrained conditions. Shear zones respond to pore pressure increments by impulsive acceleration and dilatancy, causing spontaneous deceleration followed by sustained steady-rate creep. Increasing pore pressure results in high creep rates and eventual collapse. Laboratory experiments quantitatively capture the in situ behavior of giant rockslides and lay physically-based foundations to understand the collapse of giant rockslides., Giant rockslides creep slowly for centuries and then can fail catastrophically, posing major threats to society. Here, the authors use observational and experimental evidence to quantitatively capture the full spectrum of giant rockslide behaviour until collapse, that is modulated by hydro-mechanical response to short-term fluid pressure perturbations.

Published
2020

14. Frictional properties of basalt experimental faults and implications for volcano-tectonic settings and geo-energy sites

Author

Marco M. Scuderi, Cristiano Collettini, Giulio Di Toro, Piercarlo Giacomel, Roberta Ruggieri, and Elena Spagnuolo

Subjects
Shearing (physics), Fault slip modes, 010504 meteorology & atmospheric sciences, Slip (materials science), Cataclastic rock, 010502 geochemistry & geophysics, 01 natural sciences, Fault slip modes, Frictional stability analysis, Heterogeneous fault microstructure, Strong faults, Unaltered basalts, earthquakes, Geophysics, Shear (geology), 13. Climate action, Fault gouge, Heterogeneous fault microstructure, Shear velocity, Shear zone, Unaltered basalts, Petrology, Joint (geology), Frictional stability analysis, Strong faults, earthquakes, Geology, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

We performed a suite of experiments aimed at examining the frictional properties of unaltered basalts at conditions considered to be representative of slip at shallow depths in volcano-tectonic environments and in-situ geo-energy basaltic sites. Scientific drilling and field studies on exhumed subsurface faults and fractures analogues suggest that, frictional sliding in basalts can occur in shear zones within a volume of wear debris or along localized joint surfaces. To illuminate how microstructural heterogeneities affect the nucleation of slip instabilities in basalts, we sheared simulated fault gouge and bare rock surfaces at low normal stresses (4–30 MPa) at ambient temperature, under room-dry and wet conditions. We performed velocity steps (0.1–300 μm/s) and slide-hold-slides (30–3000 s holds) to determine the frictional stability and healing properties of basalts. In all the tests, we observed high friction coefficient associated with important frictional restrengthening. Overall, our results show that microstructural heterogeneities strongly affect the friction velocity dependence of basalts: while for normal stresses ≥10 MPa, shear localization accompanied by cataclasis and grain size reduction favors the transition to velocity weakening behavior of powdered samples, on bare surfaces gouge production during shearing promotes a transition to a velocity strengthening behavior. Our results imply that at the tested conditions, friction instabilities may promptly nucleate in shear zones where deformation within (unaltered) basaltic gouge layers is localized, such as those located along volcanic flanks, while joint surfaces characterized by rough rock-on-rock contacts are less prone to unstable slip, which is suppressed at velocities ≥10 μm/s.

Published
2021

15. Ultrahigh Energy Neutrinos at the Pierre Auger Observatory

Author

P. Abreu, M. Aglietta, M. Ahlers, E. J. Ahn, I. F. M. Albuquerque, D. Allard, I. Allekotte, J. Allen, P. Allison, A. Almela, J. Alvarez Castillo, J. Alvarez-Muñiz, R. Alves Batista, M. Ambrosio, A. Aminaei, L. Anchordoqui, S. Andringa, T. Antičić, C. Aramo, E. Arganda, F. Arqueros, H. Asorey, P. Assis, J. Aublin, M. Ave, M. Avenier, G. Avila, T. Bäcker, A. M. Badescu, M. Balzer, K. B. Barber, A. F. Barbosa, R. Bardenet, S. L. C. Barroso, B. Baughman, J. Bäuml, J. J. Beatty, B. R. Becker, K. H. Becker, A. Bellétoile, J. A. Bellido, S. BenZvi, C. Berat, X. Bertou, P. L. Biermann, P. Billoir, F. Blanco, M. Blanco, C. Bleve, H. Blümer, M. Boháčová, D. Boncioli, C. Bonifazi, R. Bonino, N. Borodai, J. Brack, I. Brancus, P. Brogueira, W. C. Brown, R. Bruijn, P. Buchholz, A. Bueno, R. E. Burton, K. S. Caballero-Mora, B. Caccianiga, L. Caramete, R. Caruso, A. Castellina, O. Catalano, G. Cataldi, L. Cazon, R. Cester, J. Chauvin, S. H. Cheng, A. Chiavassa, J. A. Chinellato, J. Chirinos Diaz, J. Chudoba, M. Cilmo, R. W. Clay, M. R. Coluccia, R. Conceição, F. Contreras, H. Cook, M. J. Cooper, J. Coppens, A. Cordier, S. Coutu, C. E. Covault, A. Creusot, A. Criss, J. Cronin, A. Curutiu, S. Dagoret-Campagne, R. Dallier, B. Daniel, S. Dasso, K. Daumiller, B. R. Dawson, R. M. de Almeida, M. De Domenico, C. De Donato, S. J. de Jong, G. De La Vega, W. J. M. de Mello Junior, J. R. T. de Mello Neto, I. De Mitri, V. de Souza, K. D. de Vries, L. del Peral, M. del Río, O. Deligny, H. Dembinski, N. Dhital, C. Di Giulio, M. L. Díaz Castro, P. N. Diep, F. Diogo, C. Dobrigkeit, W. Docters, J. C. D'Olivo, P. N. Dong, A. Dorofeev, J. C. dos Anjos, M. T. Dova, D. D'Urso, I. Dutan, J. Ebr, R. Engel, M. Erdmann, C. O. Escobar, J. Espadanal, A. Etchegoyen, P. Facal San Luis, H. Falcke, G. Farrar, A. C. Fauth, N. Fazzini, A. P. Ferguson, B. Fick, A. Filevich, A. Filipčič, S. Fliescher, C. E. Fracchiolla, E. D. Fraenkel, O. Fratu, U. Fröhlich, B. Fuchs, R. Gaior, R. F. Gamarra, S. Gambetta, B. García, S. T. Garcia Roca, D. Garcia-Gamez, D. Garcia-Pinto, A. Gascon Bravo, H. Gemmeke, P. L. Ghia, M. Giller, J. Gitto, H. Glass, M. S. Gold, G. Golup, F. Gomez Albarracin, M. Gómez Berisso, P. F. Gómez Vitale, P. Gonçalves, J. G. Gonzalez, B. Gookin, A. Gorgi, P. Gouffon, E. Grashorn, S. Grebe, N. Griffith, M. Grigat, A. F. Grillo, Y. Guardincerri, F. Guarino, G. P. Guedes, P. Hansen, D. Harari, T. A. Harrison, J. L. Harton, A. Haungs, T. Hebbeker, D. Heck, A. E. Herve, C. Hojvat, N. Hollon, V. C. Holmes, P. Homola, J. R. Hörandel, P. Horvath, M. Hrabovský, D. Huber, T. Huege, A. Insolia, F. Ionita, A. Italiano, C. Jarne, S. Jiraskova, M. Josebachuili, K. Kadija, K. H. Kampert, P. Karhan, P. Kasper, I. Katkov, B. Kégl, B. Keilhauer, A. Keivani, J. L. Kelley, E. Kemp, R. M. Kieckhafer, H. O. Klages, M. Kleifges, J. Kleinfeller, J. Knapp, D.-H. Koang, K. Kotera, N. Krohm, O. Krömer, D. Kruppke-Hansen, F. Kuehn, D. Kuempel, J. K. Kulbartz, N. Kunka, G. La Rosa, C. Lachaud, D. LaHurd, L. Latronico, R. Lauer, P. Lautridou, S. Le Coz, M. S. A. B. Leão, D. Lebrun, P. Lebrun, M. A. Leigui de Oliveira, A. Letessier-Selvon, I. Lhenry-Yvon, K. Link, R. López, A. Lopez Agüera, K. Louedec, J. Lozano Bahilo, L. Lu, A. Lucero, M. Ludwig, H. Lyberis, M. C. Maccarone, C. Macolino, S. Maldera, D. Mandat, P. Mantsch, A. G. Mariazzi, J. Marin, V. Marin, I. C. Maris, H. R. Marquez Falcon, G. Marsella, D. Martello, L. Martin, H. Martinez, O. Martínez Bravo, H. J. Mathes, J. Matthews, J. A. J. Matthews, G. Matthiae, D. Maurel, D. Maurizio, P. O. Mazur, G. Medina-Tanco, M. Melissas, D. Melo, E. Menichetti, A. Menshikov, P. Mertsch, C. Meurer, S. Mićanović, M. I. Micheletti, I. A. Minaya, L. Miramonti, L. Molina-Bueno, S. Mollerach, M. Monasor, D. Monnier Ragaigne, F. Montanet, B. Morales, C. Morello, E. Moreno, J. C. Moreno, M. Mostafá, C. A. Moura, M. A. Muller, G. Müller, M. Münchmeyer, R. Mussa, G. Navarra, J. L. Navarro, S. Navas, P. Necesal, L. Nellen, A. Nelles, J. Neuser, P. T. Nhung, M. Niechciol, L. Niemietz, N. Nierstenhoefer, D. Nitz, D. Nosek, L. Nožka, J. Oehlschläger, A. Olinto, M. Ortiz, N. Pacheco, D. Pakk Selmi-Dei, M. Palatka, J. Pallotta, N. Palmieri, G. Parente, E. Parizot, A. Parra, S. Pastor, T. Paul, M. Pech, J. Pękala, R. Pelayo, I. M. Pepe, L. Perrone, R. Pesce, E. Petermann, S. Petrera, A. Petrolini, Y. Petrov, C. Pfendner, R. Piegaia, T. Pierog, P. Pieroni, M. Pimenta, V. Pirronello, M. Platino, M. Plum, V. H. Ponce, M. Pontz, A. Porcelli, P. Privitera, M. Prouza, E. J. Quel, S. Querchfeld, J. Rautenberg, O. Ravel, D. Ravignani, B. Revenu, J. Ridky, S. Riggi, M. Risse, P. Ristori, H. Rivera, V. Rizi, J. Roberts, W. Rodrigues de Carvalho, G. Rodriguez, I. Rodriguez Cabo, J. Rodriguez Martino, J. Rodriguez Rojo, M. D. Rodríguez-Frías, G. Ros, J. Rosado, T. Rossler, M. Roth, B. Rouillé-d'Orfeuil, E. Roulet, A. C. Rovero, C. Rühle, A. Saftoiu, F. Salamida, H. Salazar, F. Salesa Greus, G. Salina, F. Sánchez, C. E. Santo, E. Santos, E. M. Santos, F. Sarazin, B. Sarkar, S. Sarkar, R. Sato, N. Scharf, V. Scherini, H. Schieler, P. Schiffer, A. Schmidt, O. Scholten, H. Schoorlemmer, J. Schovancova, P. Schovánek, F. Schröder, S. Schulte, D. Schuster, S. J. Sciutto, M. Scuderi, A. Segreto, M. Settimo, A. Shadkam, R. C. Shellard, I. Sidelnik, G. Sigl, O. Sima, A. Śmiałkowski, R. Šmída, G. R. Snow, P. Sommers, J. Sorokin, H. Spinka, R. Squartini, Y. N. Srivastava, S. Stanic, J. Stapleton, J. Stasielak, M. Stephan, A. Stutz, F. Suarez, T. Suomijärvi, A. D. Supanitsky, T. Šuša, M. S. Sutherland, J. Swain, Z. Szadkowski, M. Szuba, A. Tapia, M. Tartare, O. Taşcău, R. Tcaciuc, N. T. Thao, D. Thomas, J. Tiffenberg, C. Timmermans, W. Tkaczyk, C. J. Todero Peixoto, G. Toma, L. Tomankova, B. Tomé, A. Tonachini, P. Travnicek, D. B. Tridapalli, G. Tristram, E. Trovato, M. Tueros, R. Ulrich, M. Unger, M. Urban, J. F. Valdés Galicia, I. Valiño, L. Valore, A. M. van den Berg, E. Varela, B. Vargas Cárdenas, J. R. Vázquez, R. A. Vázquez, D. Veberič, V. Verzi, J. Vicha, M. Videla, L. Villaseñor, H. Wahlberg, P. Wahrlich, O. Wainberg, D. Walz, A. A. Watson, M. Weber, K. Weidenhaupt, A. Weindl, F. Werner, S. Westerhoff, B. J. Whelan, A. Widom, G. Wieczorek, L. Wiencke, B. Wilczyñska, H. Wilczyñski, M. Will, C. Williams, T. Winchen, M. Wommer, B. Wundheiler, T. Yamamoto, T. Yapici, P. Younk, G. Yuan, A. Yushkov, B. Zamorano Garcia, E. Zas, D. Zavrtanik, M. Zavrtanik, I. Zaw, A. Zepeda, Y. Zhu, M. Zimbres Silva, and M. Ziolkowski

Subjects
Physics, QC1-999
Abstract

The observation of ultrahigh energy neutrinos (UHEνs) has become a priority in experimental astroparticle physics. UHEνs can be detected with a variety of techniques. In particular, neutrinos can interact in the atmosphere (downward-going ν) or in the Earth crust (Earth-skimming ν), producing air showers that can be observed with arrays of detectors at the ground. With the surface detector array of the Pierre Auger Observatory we can detect these types of cascades. The distinguishing signature for neutrino events is the presence of very inclined showers produced close to the ground (i.e., after having traversed a large amount of atmosphere). In this work we review the procedure and criteria established to search for UHEνs in the data collected with the ground array of the Pierre Auger Observatory. This includes Earth-skimming as well as downward-going neutrinos. No neutrino candidates have been found, which allows us to place competitive limits to the diffuse flux of UHEνs in the EeV range and above.

Published
2013
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17. Application of Constitutive Friction Laws to Glacier Seismicity

Author

Richard B. Alley, Sridhar Anandakrishnan, Marco M. Scuderi, Chris Marone, Brett M. Carpenter, Matt J. Ikari, and Lucas K. Zoet

Subjects
geography, Geophysics, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, General Earth and Planetary Sciences, Glacier, Induced seismicity, 010502 geochemistry & geophysics, 01 natural sciences, Geology, 0105 earth and related environmental sciences
Published
2020
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18. Bifurcations at the Stability Transition of Earthquake Faulting

Author

Chris Marone, Carolina Giorgetti, Marco M. Scuderi, Deepa Mele Veedu, Sylvain Barbot, Cristiano Collettini, and Earth Observatory of Singapore

Subjects
velocity, Earthquake, Slow Slip, phenomena, subduction zone, complex, earthquake, faulting, rupture, slow slip, cascadia, Stability (probability), slow slip event, General [Science], Geophysics, evolution, origin, frictional-properties, General Earth and Planetary Sciences, fluid-flow, mechanics, Seismology, Geology, granite
Abstract

Tectonic faults typically break in a single rupture mode within the range of styles from slow slip to dynamic earthquake failure. However, in increasingly well‐documented instances, the same fault segment fails in both slow and fast modes within a short period, as in the sequences that culminated in the 2011 Mw = 9.0 Tohoku‐Oki, Japan, and 2014 Mw = 8.2 Iquique, Chile, earthquakes. Why slow slip alternates with dynamic rupture in certain regions but not in others is not well understood. Here, we integrate laboratory experiments and numerical simulations to investigate the physical conditions leading to cycles where the two rupture styles alternate. We show that a bifurcation takes place near the stability transition with sequences encompassing various rupture modes under constant loading rate. The range of frictional instabilities and slip cycles identified in this study represents important end‐members to understand the interaction of slow and fast slip on the same fault segment. Ministry of Education (MOE) Published version This work is funded by the Earth Observatory of Singapore and by the Singapore Ministry of Education and also the 2017 Stephen Riady Funding from the Earth Observatory of Singapore (M4430260.B50.500000).

Published
2020
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19. Modelación matemática hidrológica-hidráulica del escurrimiento superficial en la cuenca del A° Pavón (Santa Fe, Argentina)

Author

Carlos M. Scuderi, Gerardo A. Riccardi, Hernan R. Stenta, and Pedro A. Basile

Subjects
Hydrology, Technology, geography, Modelación matemática distribuida, geography.geographical_feature_category, General Medicine, Structural basin, Field (geography), Rainwater harvesting, Water resources, Parana river, Arroyo Pavón, Cuenca de llanura, Digital elevation model, Surface runoff, Geology, Channel (geography)
Abstract

Se presenta la implementación y calibración preliminar de un modelo matemático distribuido, hidrológico- hidráulico de escurrimiento superficial físicamente basado en la cuenca del A° Pavón (sur de la provincia de Santa Fe). La cuenca tiene una superficie de aproximadamente 3143 km2 y su principal curso es el tramo: canal San Urbano-A. Sauce –A° Pavón, con descarga al río Paraná. Se utilizó como modelo digital del terreno la información proveniente de cartas topográficas del Instituto Geográfico Nacional (IGN), con agregamiento en celdas de 150 m x 150 m. Adicionalmente se contó con información de red de cursos desde cartas topográficas del IGN, imágenes Google Earth ©; recorridas de campo y proyectos existentes. El modelo quedó constituido con 139717 celdas y una red de cursos de 895 km y fue calibrado preliminarmente con información hidrológica e hidráulica de un evento extraordinario ocurrido el 15 de enero de 2017. La explotación del modelo, en este primer nivel de avance, permitió realizar la delimitación de áreas inundadas en la cuenca; la determinación de zonas con riesgo para vidas humanas y mapas de permanencias de agua para el evento extraordinario y una serie de eventos hipotéticos de diferentes recurrencias. Estos resultados son un aporte en la planificación territorial de los recursos hídricos en la zona de estudio. Si bien se evidencia un severo déficit de información, los primeros resultados obtenidos en la transformación lluvia caudal y propagación de escurrimiento superficial son aceptables.

Published
2018
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20. Strength evolution of simulated carbonate-bearing faults: The role of normal stress and slip velocity

Author

Eugenio Carminati, Cristiano Collettini, Marco M. Scuderi, Telemaco Tesei, and Marco Mercuri

Subjects
Calcite, Carbonate-bearing faults, Friction, Microstructures, 010504 meteorology & atmospheric sciences, friction, Geology, Crust, Cataclastic rock, Slip (materials science), Plasticity, 010502 geochemistry & geophysics, 01 natural sciences, chemistry.chemical_compound, carbonate-bearing faults, chemistry, Fault gouge, microstructures, calcite, geology, Carbonate, Pressure solution, Petrology, human activities, 0105 earth and related environmental sciences
Abstract

A great number of earthquakes occur within thick carbonate sequences in the shallow crust. At the same time, carbonate fault rocks exhumed from a depth < 6 km (i.e., from seismogenic depths) exhibit the coexistence of structures related to brittle (i.e., cataclasis) and ductile deformation processes (i.e., pressure-solution and granular plasticity). We performed friction experiments on water-saturated simulated carbonate-bearing faults for a wide range of normal stresses (from 5 to 120 MPa) and slip velocities (from 0.3 to 100 μm/s). At high normal stresses (σn > 20 MPa) fault gouges undergo strain-weakening, that is more pronounced at slow slip velocities, and causes a significant reduction of frictional strength, from μ = 0.7 to μ = 0.47. Microstructural analysis show that fault gouge weakening is driven by deformation accommodated by cataclasis and pressure-insensitive deformation processes (pressure solution and granular plasticity) that become more efficient at slow slip velocity. The reduction in frictional strength caused by strain weakening behaviour promoted by the activation of pressure-insensitive deformation might play a significant role in carbonate-bearing faults mechanics.

Published
2018
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21. Do scaly clays control seismicity on faulted shale rocks?

Author

Marie Violay, L. F. Orellana, Marco M. Scuderi, and Cristiano Collettini

Subjects
education.field_of_study, 010504 meteorology & atmospheric sciences, Population, Geochemistry, Radioactive waste, Slip (materials science), Induced seismicity, 010502 geochemistry & geophysics, 01 natural sciences, Tectonics, Geophysics, Deformation mechanism, Space and Planetary Science, Geochemistry and Petrology, Bed, Earth and Planetary Sciences (miscellaneous), education, Oil shale, Geology, 0105 earth and related environmental sciences
Abstract

One of the major challenges regarding the disposal of radioactive waste in geological formations is to ensure isolation of radioactive contamination from the environment and the population. Shales are suitable candidates as geological barriers. However, the presence of tectonic faults within clay formations put the long-term safety of geological repositories into question. In this study, we carry out frictional experiments on intact samples of Opalinus Clay, i.e. the host rock for nuclear waste storage in Switzerland. We report experimental evidence suggesting that scaly clays form at low normal stress (≤20 MPa), at sub-seismic velocities (≤300 μm/s) and is related to pre-existing bedding planes with an ongoing process where frictional sliding is the controlling deformation mechanism. We have found that scaly clays show a velocity-weakening and -strengthening behaviour, low frictional strength, and poor re-strengthening over time, conditions required to allow the potential nucleation and propagation of earthquakes within the scaly clays portion of the formation. The strong similarities between the microstructures of natural and experimental scaly clays suggest important implications for the slip behaviour of shallow faults in shales. If natural and anthropogenic perturbations modify the stress conditions of the fault zone, earthquakes might have the potential to nucleate within zones of scaly clays controlling the seismicity of the clay-rich tectonic system, thus, potentially compromising the long-term safeness of geological repositories situated in shales.

Published
2018
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22. Frictional Properties of Opalinus Clay: Implications for Nuclear Waste Storage

Author

Cristiano Collettini, Marco M. Scuderi, Marie Violay, and L. F. Orellana

Subjects
Geophysics, 010504 meteorology & atmospheric sciences, Waste management, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Nuclear waste storage, 010502 geochemistry & geophysics, 01 natural sciences, Geology, 0105 earth and related environmental sciences
Published
2018
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23. Physical and Transport Property Variations Within Carbonate‐Bearing Fault Zones: Insights From the Monte Maggio Fault (Central Italy)

Author

Silvio Mollo, Piergiorgio Scarlato, Marco M. Scuderi, Brett M. Carpenter, Cristiano Collettini, and Fabio Trippetta

Subjects
geography, geography.geographical_feature_category, Cataclasite, 010504 meteorology & atmospheric sciences, carbonates, earthquake event, Fault (geology), 010502 geochemistry & geophysics, Overburden pressure, 01 natural sciences, physical properties, fault zone, Aquila (Italy), Seismic wave, Permeability (earth sciences), Geophysics, Fault breccia, Seismic hazard, Geochemistry and Petrology, Petrology, Porosity, Geology, Seismology, 0105 earth and related environmental sciences
Abstract

The physical characterization of carbonate–bearing normal faults is fundamental for resource development and seismic hazard. Here we report laboratory measurements of density, porosity, Vp, Vs, elastic moduli and permeability for a range of effective confining pressures (0.1-100 MPa), conducted on samples representing different structural domains of a carbonate-bearing fault. We find a reduction in porosity from the fault breccia (11.7% total and 6.2% connected) to the main fault plane (9% total and 3.5% connected), with both domains showing higher porosity compared to the protolith (6.8% total and 1.1% connected). With increasing confining pressure, P-wave velocity evolves from 4.5 km/s to 5.9 km/s in the fault breccia, is constant at 5.9 km/s approaching the fault plane and is low (4.9 km/s) in clay-rich fault domains. We find that while the fault breccia shows pressure sensitive behaviour (a reduction in permeability from 2*10−16 m2 to 2*10−17 m2), the cemented cataclasite close to the fault plane is characterized by pressure independent behaviour (permeability 4*10−17 m2). Our results indicate that the deformation processes occurring within the different fault structural domains influence the physical and transport properties of the fault zone. In-situ Vp profiles match well the laboratory measurements demonstrating that laboratory data are valuable for implications at larger scale. Combining the experimental values of elastic moduli and frictional properties it results that at shallow crustal levels M ≤ 1 earthquakes are less favoured, in agreement with earthquake-depth distribution during the L'Aquila 2009 seismic sequence that occurred on carbonates.

Published
2017
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24. Friction and scale-dependent deformation processes of large experimental carbonate faults

Author

Amir Sagy, Cristiano Collettini, Marco M. Scuderi, Telemaco Tesei, Brett M. Carpenter, Piergiorgio Scarlato, and Carolina Giorgetti

Subjects
Carbonate, Deformation, Fault, Friction, Nanoparticle, Scale, 010504 meteorology & atmospheric sciences, 010502 geochemistry & geophysics, 01 natural sciences, Physics::Fluid Dynamics, chemistry.chemical_compound, Geotechnical engineering, Shear velocity, Coefficient of friction, 0105 earth and related environmental sciences, Shearing (physics), Faults, Normal force, Geology, Mechanics, Friction, Faults, Laboratory Experiments, Condensed Matter::Soft Condensed Matter, Laboratory Experiments, chemistry, Scale dependent, Direct shear test
Abstract

We studied the frictional behaviour and deformation products of large (20 cm × 20 cm bare surfaces) experimental limestone faults. We sheared samples in a direct shear configuration, with an imposed normal force of 40–200 kN and shear velocity of 10 μm/s. The steady-state shearing of these surfaces yielded a coefficient of friction 0.7

Published
2017
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25. Stress triggering and the mechanics of fault slip behavior

Author

Marco M. Scuderi and Cristiano Collettini

Subjects
Mechanics, Acute stress, Fault slip, Geology
Abstract

Dynamic changes in the stress field during the seismic cycle of tectonic faults can control frictional stability and the mode of fault slip. Small perturbation in the stress field, like those produced by tidal stresses can influence the evolution of frictional strength and fault stability with the potential of triggering a variety of slip behaviors. However, an open question that remains still poorly understood is how amplitude and frequency of stress changes influence the triggering of an instability and the associated slip behavior, i.e. slow or fast slip.Here we reproduce in the laboratory the spectrum of fault slip behaviors, from slow-slip to dynamic stick-slip, by matching the critical fault rheologic stiffness (kc) with the surrounding stiffness (k). We investigate the influence of normal stress variations on the slip style of a quartz rich fault gouge at the stability boundary, i.e. k/kc slightly less than one, by adopting two techniques: 1) instantaneous step-like changes and 2) sinusoidal variations in normal stress. For the latter case, modulations of normal stress were chosen to have amplitudes greater, less or equal to the typical stress drop observed during unperturbed experiments. Also, the period was varied to be greater, less or equal to the typical recurrence time of laboratory slow-slip events. During the experiments, we continuously record ultrasonic wave velocity to monitor the microphysical state of the fault. We find that frictional stability is profoundly affected by variation in normal stress giving rise to a variety of slip behaviors. Furthermore, during strain accumulation and fabric development, changes in normal stress permanently influence the microphysical state of the fault gouge increasing kc and producing a switch from slow to fast stick-slip. Our results indicate that perturbations in the stress state can trigger a variety of slip behaviors along the same fault patch. These results have important implications for the formulation of constitutive laws in the framework of rate- and state- friction, highlighting the necessity to account for the microphysical state of the fault in order to improve our understanding of frictional stability.

Published
2020
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26. Frictional strength, stability, and healing properties of basalt faults for CO2 storage purposes

Author

Elena Spagnuolo, Cristiano Collettini, Marco M. Scuderi, Giulio Di Toro, Piercarlo Giacomel, and Roberta Ruggieri

Subjects
Basalt, Geotechnical engineering, Co2 storage, Stability (probability), Geology
Abstract

Despite the numerous advantages of storing CO2 into basalts by dissolving carbon dioxide into water prior to its injection, the large amount of H2O required for this operation poses an increased risk of fluid overpressure into the fault/fracture networks, and renders the seismicity analysis pivotal to upscale this storage method to voluminous basaltic occurrences diffused worldwide.To deepen our knowledge on the frictional strength, stability, and the healing properties of basalt-built faults, we carried out friction tests on basalts from Mt. Etna using the biaxial deformation machine, BRAVA, and the rotary-shear apparatus, SHIVA (HP-HT laboratory of INGV-Rome, Italy). Specimens were selected for their relative abundance of olivine and pyroxene crystals, i.e. the main sources of divalent cations in silicate rocks necessary to trap CO2 into basalts.Experiments were performed both on synthetic powdered samples and bare surfaces, at room-dry and water drained-saturated conditions, at room temperature and pressure. Bare surfaces consisted in basalt slabs and hollowed cylinders, which were mounted on BRAVA and SHIVA apparatus, respectively. Samples were subjected to 5 to 30 MPa normal stress (σn) for powdered samples and in the range 5 to 10 MPa for bare surfaces.At the investigated normal stresses, frictional sliding data obey Byerlee’s law for friction, with the friction coefficient µ = 0.59 – 0.78. Differences in μ mainly reflect sample variability, different experimental configurations, sample geometry, and, to a lesser extent, the boundary conditions (dry/wet). However, in detail, basalt slabs are generally characterized by the highest friction coefficient and hollow cylinders exhibit a slight increase in friction coefficient with increasing shear displacement, due to the progressive slip hardening resulting from gouge production during frictional sliding.Velocity step increases were conducted on BRAVA after steady values of friction were attained (~ 6.5-7.5 mm for gouge and ~ 3 mm slip for bare surfaces) and consisted in velocity sequences from 0.1 to 300 µm s-1, with ~ 500 μm displacement for each step. Rate-and-state friction experiments show opposite mechanical behavior between bare surfaces and synthetic fault gouge: while bare surfaces experience a transition from rate-weakening at low sliding velocity (V) to rate-strengthening behavior at higher V without any clear dependence on the applied σn, gouge revealed a negative trend of (a-b) with shear velocity at σn > 5 MPa and a velocity-weakening behavior at V ≥ 30 µm s-1, regardless of experimental conditions. We ascribe this different behavior to shear delocalization owing to frictional wear production in bare surfaces, and to shear localization accompanied by grain size reduction along the Riedel R1 and boundary B shear zones in fault gouges, as also confirmed by microstructural analysis.The velocity weakening behavior of fault gouge, coupled with the fast healing rates retrieved from slide-hold-slide experiments (500 µm displacement cumulated at V = 10 µm/s followed by hold times from 30 to 3000 s), define high strength zones that are potentially seismogenic. Conversely, velocity strengthening behavior of bare surfaces promotes aseismic creep at V ≥ 100 µm s-1, regardless of the faster restrengthening compared to fault gouge.

Published
2020
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27. Undrained loading in basal shear zones modulates the slow-to-fast transition of giant creeping rockslides

Author

Marco M. Scuderi, Cristiano Collettini, Federico Agliardi, and Nicoletta Fusi

Subjects
Basal (phylogenetics), Geotechnical engineering, Rockslide, Shear zone, Geology
Abstract

Giant rockslides creep for centuries and then can fail catastrophically posing major threats to society. There is growing evidence that creeping landslides are widespread worldwide and extremely sensitive to hydrological forcing, especially in climate change scenarios. Rockslide creep is the results of progressive rock failure processes, leading to rock damage accumulation, permeability enhancement and strain localization within basal shear zones similar to tectonic faults. As shear zone accumulate strain, they become thicker and less permeable, favoring the development of perched aquifers. Since then, the creep behavior of mature rockslides becomes dominated by hydro-mechanical interaction with external triggers, e.g. rainfall and snowmelt. However, the mechanisms regulating the slow-to-fast transition toward their catastrophic collapse remain elusive, and statistical and simplified mathematical models used for collapse prediction are usually unable to account for the full spectrum of observed slip behaviors.Here we couple laboratory experiments on natural rockslide shear zone material, sampled from high quality drillcores, and in situ observations (groundwater level and surface displacement) to investigate the mechanism of rockslide response to short-term pore pressure variations within basal shear zones at the Spriana rockslide (Italy). Using a biaxial apparatus within a pressure vessel, we characterized the strength and permeability of the phyllosilicate-rich shear zone material at in situ stress, as well as the rate and state frictional properties for shear rates typical of the slow-to-fast transition of real rockslides. Then we carried out non-conventional pore pressure-step creep experiments, in which shear stress is maintained at subcritical levels and pore pressure is increased stepwise while monitoring shear zone slip and dilatancy until runaway failure.Our results, that are quantitatively consistent with in situ monitoring observations, provide a scale-independent demonstration that short-term pore pressure variations originate a full spectrum of creep styles, modulated by slip-induced undrained conditions. Shear zones respond to fluid pressure increments by impulsive acceleration and dilatancy, causing spontaneous deceleration followed by sustained steady-rate creep. Increasing fluid pressure results in high creep rates and eventual collapse. Laboratory experiments quantitatively capture the in situ behavior of giant rockslides, providing physically-based basis to improve forecasting models for giant mature rockslides in crystalline rocks.

Published
2020
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28. Modeling of virgin state and forming operation in embedded phase change memory (PCM)

Author

Daniele Ielmini, A. Redaelli, E. Petroni, Giuseppe Nicotra, M. Baldo, M. Borghi, Octavian Melnic, Paola Zuliani, M. Scuderi, and A. Motta

Subjects
Phase-change memory, chemistry.chemical_compound, Work (thermodynamics), Reliability (semiconductor), Materials science, chemistry, Mechanical engineering, Energy landscape, Forming processes, State (computer science), GeSbTe
Abstract

Embedded phase change memory (PCM) show optimized performance and reliability thanks to Ge enrichment of the active GeSbTe material. However, excess Ge tends to segregate in the virgin state, which requires an initial forming process for initializing the PCM device. This work presents the detailed energy landscape model for embedded PCMs before forming and after forming. The model predicts the distribution of PCM resistance as a function of forming conditions and read temperature. The model is validated by physical and electrical data, providing a physical interpretation of the forming process in terms of nanoscale element migration within the PCM.

Published
2020

29. Beyond Byerlee friction, weak faults and implications for slip behavior

Author

Marco M. Scuderi, Cristiano Collettini, Brett M. Carpenter, Telemaco Tesei, and Cecilia Viti

Subjects
fault, earthquakes, friction, rheology, 010504 meteorology & atmospheric sciences, Nucleation, Slip (materials science), Fault (geology), 010502 geochemistry & geophysics, 01 natural sciences, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Softening, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Crust, Tectonics, Geophysics, Creep, Space and Planetary Science, Rock types, Geology, Seismology
Abstract

Some faults are considered strong because their strength is consistent with the Coulomb criterion under Byerlee's friction, 0.6 μ 0.85 . In marked contrast, numerous studies have documented significant fault weakening induced by fluid-assisted reaction softening that generally takes place during the long-term evolution of the fault. Reaction softening promotes the replacement of strong minerals with phyllosilicates. Phyllosilicate development within foliated and interconnected fault networks has been documented at different crustal depths, in different tectonic regimes and from a great variety of rock types, nominating fluid-assisted reaction softening as a general weakening mechanism within the seismogenic crust. This weakening originates at the grain-scale and is transmitted to the entire fault zone via the interconnectivity of the phyllosilicate-rich zones resulting in a friction as low as 0.1 μ 0.3 . Collectively, geological data and results from laboratory experiments provide strong supporting evidence for structural and frictional heterogeneities within crustal faults. In these structures, creep along weak and rate-strengthening fault patches can promote earthquake nucleation within adjacent strong and locked, rate-weakening portions. Some new frontiers on this research topic regard: 1) when and how a seismic rupture nucleating within a strong patch might propagate within a weak velocity strengthening fault portion, and 2) if creep and slow slip can be accurately detected within the earthquake preparatory phase and therefore represent a reliable earthquake precursor.

Published
2019
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30. The role of shale content and pore-water saturation on frictional properties of simulated carbonate faults

Author

Stefania Petroselli, Marco M. Scuderi, M. Brignoli, Lorenzo Osculati, Fabio Trippetta, Elisa Tinti, Cristiano Collettini, Giorgio Volonté, Stefano Mantica, and Roberta Ruggieri

Subjects
geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, clay, Slip (materials science), Fault (geology), 010502 geochemistry & geophysics, 01 natural sciences, friction carbonate faults, fault slip behavior, Pore water pressure, Geophysics, Shear (geology), Fault gouge, Deformation (engineering), Composite material, Oil shale, Geology, Strengthening mechanisms of materials, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

The presence of weak phyllosilicates in mature carbonate fault zones has been invoked to explain weak faults. However, the relation between frictional strength, fault stability, mineralogical composition, and fabric of fault gouge, composed of strong and weak minerals, is poorly constrained. We used a biaxial apparatus to systematically shear different mixtures of shale (68% clay, 23% quartz and 4% plagioclase) and calcite, as powdered gouge, at room temperature, under constant normal stresses of 30, 50, 100 MPa and under room-dry and pore fluid-saturated conditions, i.e. CaCO3-equilibrated water. We performed 30 friction experiments during which velocity-stepping and slide-hold-slide tests were employed to assess frictional stability and to measure frictional healing, respectively. Our frictional data indicate that the mineralogical composition of fault gouges significantly affects frictional strength, stability, and healing as well as the presence of CaCO3-equilibrated water. Under room-dry condition, the increasing shale content determines a reduction in frictional strength, from μ = 0.71 to μ = 0.43, a lowering of the healing rates and a transition from velocity-weakening to velocity-strengthening behavior. Under wet condition, with increasing shale content we observe a more significant reduction in frictional strength (μ = 0.65–0.37), a near-zero healing and a velocity strengthening behavior. Microstructural investigations evidence a transition from localized deformation promoted by grain size reduction, in calcite-rich samples, to a more distributed deformation with frictional sliding along clay-enriched shear planes in samples with shale content greater than 50%. For faults cutting across sedimentary sequences composed of carbonates and clay-rich sediments, our results suggest that clay concentration and its ability to form foliated and interconnected networks promotes important heterogeneities in fault strength and slip behavior.

Published
2021
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31. Experimental constraints on the relationship between clay abundance, clay fabric, and frictional behavior for the <scp>C</scp> entral <scp>D</scp> eforming <scp>Z</scp> one of the <scp>S</scp> an <scp>A</scp> ndreas <scp>F</scp> ault

Author

Marco M. Scuderi, Brett M. Carpenter, Chris Marone, Laurence N. Warr, Jasmaria Wojatschke, and Demian M. Saffer

Subjects
geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Slip (materials science), Aseismic creep, Fault (geology), 010502 geochemistry & geophysics, San Andreas Fault Observatory at Depth, 01 natural sciences, Shear (sheet metal), Geophysics, Geochemistry and Petrology, Fault gouge, Geotechnical engineering, Petrology, Clay minerals, Quartz, Geology, 0105 earth and related environmental sciences
Abstract

The presence of smectite (saponite) in fault gouge from the Central Deforming Zone of the San Andreas Fault at Parkfield, CA has been linked to low mechanical strength and aseismic slip. However, the precise relationship between clay mineral structure, fabric development, fault strength, and the stability of frictional sliding is not well understood. We address these questions through the integration of laboratory friction tests and FIB-SEM analysis of fault rock recovered from the San Andreas Fault Observatory at Depth (SAFOD) borehole. Intact fault rock was compared with experimentally sheared fault gouge and different proportions of either quartz clasts or SAFOD clasts extracted from the sample. Nano-textural measurements show the development of localized clay particle alignment along shear folia developed within synthetic gouges; such slip planes have multiples of random distribution (MRD) values of 3.0–4.9. The MRD values measured are higher than previous estimates (MRD 1.5) that show lower degrees of shear localization and clay alignment averaged over larger volumes. The intact fault rock exhibits less well-developed nano-clay fabrics than the experimentally sheared materials, and MRD values decrease with smectite content. We show that the abundance, strength, and shape of clasts all influence fabric evolution via strain localization: quartz clasts yield more strongly developed clay fabrics than serpentine-dominated SAFOD clasts. Our results suggest that (1) both clay abundance and the development of nano-scale fabrics play a role in fault zone weakening and (2) aseismic creep is promoted by slip along clay shears with >20 wt % smectite content and MRD values ≥2.7.

Published
2016
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32. Frequency, pressure, and strain dependence of nonlinear elasticity in Berea Sandstone

Author

Jérôme Fortin, Chris Marone, Lucas Xan Pimienta, Parisa Shokouhi, Thibault Candela, Jacques Rivière, Alexandre Schubnel, Paul A. Johnson, and Marco M. Scuderi

Subjects
nonlinear acoustics, Materials science, 010504 meteorology & atmospheric sciences, Geological Survey Netherlands, Modulus, Mineralogy, 010502 geochemistry & geophysics, acousto-elasticity, Berea sandstone, frequency dependence, nonlinear elasticity, ultrasonic testing, earth and planetary sciences, geophysics, 01 natural sciences, Nonlinear acoustics, Softening, 0105 earth and related environmental sciences, Energy, Orders of magnitude (frequency), Mechanics, Geo, Nonlinear system, GM - Geomodelling, Geophysics, Amplitude, Harmonics, Harmonic, General Earth and Planetary Sciences, ELSS - Earth, Life and Social Sciences
Abstract

Acoustoelasticity measurements in a sample of room dry Berea sandstone are conducted at various loading frequencies to explore the transition between the quasi‐static ( ) and dynamic (few kilohertz) nonlinear elastic response. We carry out these measurements at multiple confining pressures and perform a multivariate regression analysis to quantify the dependence of the harmonic content on strain amplitude, frequency, and pressure. The modulus softening (equivalent to the harmonic at 0f) increases by a factor 2–3 over 3 orders of magnitude increase in frequency. Harmonics at 2f, 4f, and 6f exhibit similar behaviors. In contrast, the harmonic at 1f appears frequency independent. This result corroborates previous studies showing that the nonlinear elasticity of rocks can be described with a minimum of two physical mechanisms. This study provides quantitative data that describes the rate dependency of nonlinear elasticity. These findings can be used to improve theories relating the macroscopic elastic response to microstructural features.

Published
2016
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34. Caracterización de desastres naturales y tecnológicos con énfasis en desastres hidrológicos

Author

Hernan R. Stenta, Raul Postiglione, Carlos M. Scuderi, and Gerardo A. Riccardi

Subjects
Desastres naturales y tecnológicos, Technology, Natural and technological disasters, Disaster databases, Bases de datos de desastres, General Medicine, Desastres hidrológicos, Hydrological disasters
Abstract

Este trabajo da un panorama sobre los desastres asociados a factores naturales y tecnológicos. Se usa la base de datos EM-DAT de la Universidad de Louvain (Bélgica), que cuenta con datos desde el año 1900 hasta el 2018. Los desastres naturales prevalecen sobre los tecnológicos, respecto de la cantidad la relación es 66% a 34%, en cuanto a víctimas fatales los registros indican que el 93.2% está generado por desastres naturales, con relación a la cantidad de afectados la participación de los desastres de origen natural asciende al 99.8% y al considerar las pérdidas materiales los desastres naturales aportan el 99.2%. Además, se obtuvieron los siguientes resultados: a) respecto de la cantidad, los desastres hidrológicos ocupan el primer lugar, con un 38% a nivel mundial, 57% en Sudamérica y 58% en Argentina; b) en cuanto a cantidad de víctimas fatales, a nivel mundial los desastres climatológicos explican el 36%, mientras que en Sudamérica y Argentina son los geofísicos los que generan el 68% y el 87%, respectivamente; c) considerando los afectados, los desastres hidrológicos producen el 48% a nivel mundial y el 95.7% en Argentina, mientras que los climatológicos generan el 47% en Sudamérica; y d) respecto de las pérdidas económicas, en el mundo los desastres meteorológicos aportan el 44%, en Sudamérica los geofísicos generan el 42% y en Argentina los hidrológicos producen el 74%. En Argentina los desastres hidrológicos son los de mayor ocurrencia, los que producen la mayor cantidad de afectados y de pérdidas económicas, no así respecto a víctimas fatales, que contribuyen “solo” con el 8%. Cabe destacar la importancia de las políticas de planificación del uso del recurso hídrico así como también la gestión previa, durante y posterior a la ocurrencia de los desastres hídricos. Fil: Scuderi, Carlos. Universidad Nacional de Rosario, Facultad de Ciencias Exactas, Ingeniería y Agrimensura, Escuela de ingeniería Civil, Departamento de Hidráulica. Rosario, Santa Fe, Argentina. Fil: Postiglione, Raúl. Universidad Nacional de Rosario, Facultad de Ciencias Exactas, Ingeniería y Agrimensura, Escuela de ingeniería Civil, Departamento de Hidráulica. Rosario, Santa Fe, Argentina. Fil: Riccardi, Gerardo. Universidad Nacional de Rosario, Facultad de Ciencias Exactas, Ingeniería y Agrimensura, Escuela de ingeniería Civil, Departamento de Hidráulica. Rosario, Santa Fe, Argentina. Fil: Stenta, Hernan. Universidad Nacional de Rosario, Facultad de Ciencias Exactas, Ingeniería y Agrimensura, Escuela de ingeniería Civil, Departamento de Hidráulica. Rosario, Santa Fe, Argentina.

Published
2019

35. Experimental insights into fault reactivation in gouge-filled fault zones

Author

Telemaco Tesei, Marco M. Scuderi, Cristiano Collettini, and Carolina Giorgetti

Subjects
010504 meteorology & atmospheric sciences, fault reactivation, friction, Magnitude (mathematics), Fault (geology), 01 natural sciences, stress field orientation, localization, Stress (mechanics), stress, pressure, Brittleness, Geochemistry and Petrology, fault strength, propagation, Earth and Planetary Sciences (miscellaneous), triaxial saw-cut experiments, Petrology, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, Deformation (mechanics), transition, slip-tendency analysis, gouge-bearing faults, failure, Stress field, Geophysics, fracture, Space and Planetary Science, flow, Fracture (geology), Differential stress, Geology
Abstract

Faults in the brittle crust constitute preexisting weakness zones that can be reactivated depending on their friction, orientation within the local stress field, and stress field magnitude. Analytical approaches to evaluate the potential for fault reactivation are generally based on the assumption that faults are ideal planes characterized by zero thickness and constant friction. However, natural faults are complex structures that typically host thick fault rocks. Here we experimentally investigate the reactivation of gouge-bearing faults and compare the resulting data with theoretical predictions based on analytical models. We simulate preexisting faults by conducting triaxial experiments on sandstone cylinders containing saw-cuts filled with a clay-rich gouge and oriented at different angles, from 30 degrees to 80 degrees, to the maximum principal stress. Our results show the reactivation of preexisting faults when oriented at 30 degrees, 40 degrees, and 50 degrees to the maximum principal stress and the formation of a new fracture for fault orientations higher than 50 degrees. Although these observations are consistent with the fault lock-up predicted by analytical models, the differential stress required for reactivation strongly differs from theoretical predictions. In particular, unfavorable oriented faults appear systematically weaker, especially when a thick gouge layer is present. We infer that the observed weakness relates to the rotation of the stress field within the gouge layer during the documented distributed deformation that precedes unstable fault reactivation. Thus, the assumption of zero-thickness planar fault provides only an upper bound to the stress required for reactivation of misoriented faults, which might result in misleading predictions of fault reactivation.

Published
2019

36. Stabilization of fault slip by fluid injection in the laboratory and in situ

Author

Cristiano Collettini, Marco M. Scuderi, Yves Guglielmi, Frédéric Cappa, Jean Philippe Avouac, Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Dipartimento di Scienze della Terra, Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome] (UNIROMA), Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Palermo (INGV), Istituto Nazionale di Geofisica e Vulcanologia, Earth Science Division [LBNL Berkeley] (ESD), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), California Institute of Technology (CALTECH), Università degli Studi di Roma 'La Sapienza' = Sapienza University [Rome], Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), and Università degli Studi di Roma 'La Sapienza' [Rome]

Subjects
010504 meteorology & atmospheric sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Slip (materials science), Induced seismicity, 010502 geochemistry & geophysics, 01 natural sciences, earthquake, faults, induced seismicity, Computer Science::Hardware Architecture, Fluid dynamics, Aseismic slip, Computer Science::Operating Systems, Computer Science::Distributed, Parallel, and Cluster Computing, Research Articles, 0105 earth and related environmental sciences, Multidisciplinary, SciAdv r-articles, Aseismic creep, Mechanics, Geophysics, Creep, Fluid injection, Fault slip, human activities, Geology, Research Article
Abstract

Fluid injection experiments on laboratory and natural faults reveal a similar phase of fault opening and accelerating creep., Faults can slip seismically or aseismically depending on their hydromechanical properties, which can be measured in the laboratory. Here, we demonstrate that fault slip induced by fluid injection in a natural fault at the decametric scale is quantitatively consistent with fault slip and frictional properties measured in the laboratory. The increase in fluid pressure first induces accelerating aseismic creep and fault opening. As the fluid pressure increases further, friction becomes mainly rate strengthening, favoring aseismic slip. Our study reveals how coupling between fault slip and fluid flow promotes stable fault creep during fluid injection. Seismicity is most probably triggered indirectly by the fluid injection due to loading of nonpressurized fault patches by aseismic creep.

Published
2018
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37. Evolution of permeability across the transition from brittle failure to cataclastic flow in porous siltstone

Author

Marco M. Scuderi, Demian M. Saffer, Brett M. Carpenter, Hiroko Kitajima, and Chris Marone

Subjects
Pore water pressure, Permeability (earth sciences), Geophysics, Brittleness, Shear (geology), Geochemistry and Petrology, Compaction, Geotechnical engineering, Cataclastic rock, Porosity, Overburden pressure, Geology
Abstract

Porous sedimentary rocks fail in a variety of modes ranging from localized, brittle deformation to pervasive, cataclastic flow. To improve our understanding of this transition and its affect on fluid flow and permeability, we investigated the mechanical behavior of a siltstone unit within the Marcellus Formation, PA USA, characterized by an initial porosity ranging from 41 to 45%. We explored both hydrostatic loading paths (σ1=σ2=σ3) and triaxial loading paths (σ1>σ2=σ3) while maintaining constant effective pressure (Pe=Pc-Pp). Samples were deformed with an axial displacement rate of 0.1 μm/s (strain rate of 2x10−6 s−1). Changes in pore water volume were monitored (drained conditions) to measure the evolution of porosity. Permeability was measured at several stages of each experiment. Under hydrostatic loading, we find the onset of macroscropic grain crushing (P*) at 39 MPa. Triaxial loading experiments show a transition from brittle behavior with shear localization and compaction to cataclastic-flow as confining pressure increases. When samples fail by shear localization, permeability decreases abruptly without significant changes in porosity. Conversely, for cataclastic deformation, permeability reduction is associated with significant porosity reduction. Post-experiment observation of brittle samples show localized shear zones characterized by grain comminution. Our data show how zones of shear localization can act as barriers to fluid flow and thus modify the hydrological and mechanical properties of the surrounding rocks. Our results have important implications for deformation behavior and permeability evolution in sedimentary systems, and in particular where the stress field is influenced by injection or pumping. This article is protected by copyright. All rights reserved.

Published
2015
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38. The nature and origin of ultra high-energy cosmic rays

Author

J. R. Hörandel, P. Abreu, M. Aglietta, M. Ahlers, E. J. Ahn, I. F. M. Albuquerque, D. Allard, I. Allekotte, J. Allen, P. Allison, A. Almela, J. Alvarez Castillo, J. Alvarez Muñiz, M. Ambrosio, A. Aminaei, L. Anchordoqui, S. Andringa, T. Antičić, C. Aramo, E. Arganda, F. Arqueros, H. Asorey, P. Assis, J. Aublin, M. Ave, M. Avenier, G. Avila, T. Bäcker, A. M. Badescu, M. Balzer, K. B. Barber, A. F. Barbosa, R. Bardenet, S. L. C. Barroso, B. Baughman f, J. Bäuml, J. J. Beatty, B. R. Becker, K. H. Becker, A. Bellétoile, J. A. Bellido, S. BenZvi, C. Berat, X. Bertou, P. L. Biermann, P. Billoir, F. Blanco, M. Blanco, C. Bleve, H. Blümer, M. Boháčová, D. Boncioli, C. Bonifazi, R. Bonino, N. Borodai, J. Brack, I. Brancus, P. Brogueira, W. C. Brown, R. Bruijn i, P. Buchholz, A. Bueno, R. E. Burton, K. S. Caballero Mora, B. Caccianiga, L. Caramete, R. Caruso, A. Castellina, O. Catalano, G. Cataldi, L. Cazon, R. Cester, J. Chauvin, S. H. Cheng, A. Chiavassa, J. A. Chinellato, J. Chirinos Diaz, J. Chudoba, M. Cilmo, R. W. Clay, R. Conceição, F. Contreras, H. Cook, M. J. Cooper, J. Coppens, A. Cordier, S. Coutu, C. E. Covault, A. Creusot, A. Criss, J. Cronin, A. Curutiu, S. Dagoret Campagne, R. Dallier, B. Daniel, S. Dasso, K. Daumiller, B. R. Dawson, R. M. de Almeida, M. De Domenico, C. De Donato, S. J. de Jong, G. De La Vega, W. J. M. de Mello Junior, J. R. T. de Mello Neto, V. de Souza, K. D. de Vries, L. del Peral, M. del Río, O. Deligny, H. Dembinski, N. Dhital, C. Di Giulio, M. L. Díaz Castro, P. N. Diep, F. Diogo, C. Dobrigkeit, W. Docters, J. C. D'Olivo, P. N. Dong, A. Dorofeev, J. C. dos Anjos, M. T. Dova, D. D'Urso, I. Dutan, J. Ebr, R. Engel, M. Erdmann, C. O. Escobar, J. Espadanal, A. Etchegoyen, P. Facal San Luis, I. Fajardo Tapia, H. Falcke, G. Farrar, A. C. Fauth, N. Fazzini, A. P. Ferguson, B. Fick, A. Filevich, A. Filipčič, S. Fliescher, C. E. Fracchiolla, E. D. Fraenkel, O. Fratu, U. Fröhlich, B. Fuchs, R. Gaior, R. F. Gamarra, S. Gambetta, B. García, S. T. Garcia Roca, D. Garcia Gamez, D. Garcia Pinto, A. Gascon, H. Gemmeke, P. L. Ghia, U. Giaccari, M. Giller, H. Glass, M. S. Gold, G. Golup, F. Gomez Albarracin, M. Gómez Berisso, P. F. Gómez Vitale, P. Gonçalves, D. Gonzalez, J. G. Gonzalez, B. Gookin, A. Gorgi, P. Gouffon, E. Grashorn, S. Grebe, N. Griffith, M. Grigat, A. F. Grillo, Y. Guardincerri, F. Guarino, G. P. Guedes, A. Guzman, P. Hansen, D. Harari, T. A. Harrison, J. L. Harton, A. Haungs, T. Hebbeker, D. Heck, A. E. Herve, C. Hojvat, N. Hollon, V. C. Holmes, P. Homola, A. Horneffer, P. Horvath, M. Hrabovský, D. Huber, T. Huege, A. Insolia, F. Ionita, A. Italiano, C. Jarne, S. Jiraskova, M. Josebachuili, K. Kadija, K. H. Kampert, P. Karhan, P. Kasper, B. Kégl, B. Keilhauer, A. Keivani, J. L. Kelley, E. Kemp, R. M. Kieckhafer, H. O. Klages, M. Kleifges, J. Kleinfeller, J. Knapp, D. H. Koang, K. Kotera, N. Krohm, O. Krömer, D. Kruppke Hansen, F. Kuehn, D. Kuempel, J. K. Kulbartz, N. Kunka, G. La Rosa, C. Lachaud, D. LaHurd, L. Latronico, R. Lauer, P. Lautridou, S. Le Coz, M. S. A. B. Leão, D. Lebrun, P. Lebrun, M. A. Leigui de Oliveira, A. Letessier Selvon, I. Lhenry Yvon, K. Link, R. López, A. Lopez Agüera, K. Louedec, J. Lozano Bahilo, L. Lu, A. Lucero, M. Ludwig, H. Lyberis, M. C. Maccarone, C. Macolino, S. Maldera, D. Mandat, P. Mantsch, A. G. Mariazzi, J. Marin, V. Marin, I. C. Maris, H. R. Marquez Falcon, L. Martin, H. Martinez, O. Martínez Bravo, H. J. Mathes, J. Matthews, J. A. J. Matthews, G. Matthiae, D. Maurel, D. Maurizio, P. O. Mazur, G. Medina Tanco, M. Melissas, D. Melo, E. Menichetti, A. Menshikov, P. Mertsch, C. Meurer, S. Mićanović, M. I. Micheletti, I. A. Minaya, L. Miramonti, L. Molina Bueno, S. Mollerach, M. Monasor, D. Monnier Ragaigne, F. Montanet, B. Morales, C. Morello, E. Moreno, J. C. Moreno, M. Mostafá, C. A. Moura, M. A. Muller, G. Müller, M. Münchmeyer, R. Mussa, G. Navarra ‡, J. L. Navarro, S. Navas, P. Necesal, L. Nellen, A. Nelles, J. Neuser, P. T. Nhung, M. Niechciol, L. Niemietz, N. Nierstenhoefer, D. Nitz, D. Nosek, L. Nožka, J. Oehlschläger, A. Olinto, M. Ortiz, N. Pacheco, D. Pakk Selmi Dei, M. Palatka, J. Pallotta, N. Palmieri, G. Parente, E. Parizot, A. Parra, S. Pastor, T. Paul, M. Pech, J. Pękala, R. Pelayo, I. M. Pepe, R. Pesce, E. Petermann, S. Petrera, P. Petrinca, A. Petrolini, Y. Petrov, C. Pfendner, R. Piegaia, T. Pierog, P. Pieroni, M. Pimenta, V. Pirronello, M. Platino, M. Plum, V. H. Ponce, M. Pontz, A. Porcelli, P. Privitera, M. Prouza, E. J. Quel, S. Querchfeld, J. Rautenberg, O. Ravel, D. Ravignani, B. Revenu, J. Ridky, S. Riggi, M. Risse, P. Ristori, H. Rivera, V. Rizi, J. Roberts, W. Rodrigues de Carvalho, G. Rodriguez, J. Rodriguez Martino, J. Rodriguez Rojo, I. Rodriguez Cabo, M. D. Rodríguez Frías, G. Ros, J. Rosado, T. Rossler, M. Roth, B. Rouillé d'Orfeuil, E. Roulet, A. C. Rovero, C. Rühle, A. Saftoiu, F. Salamida, H. Salazar, F. Salesa Greus, G. Salina, F. Sánchez, C. E. Santo, E. Santos, E. M. Santos, F. Sarazin, B. Sarkar, S. Sarkar, R. Sato, N. Scharf, V. Scherini, H. Schieler, P. Schiffer, A. Schmidt, O. Scholten, H. Schoorlemmer, J. Schovancova, P. Schovánek, F. Schröder, S. Schulte, D. Schuster, S. J. Sciutto, M. Scuderi, A. Segreto, M. Settimo, A. Shadkam, R. C. Shellard, I. Sidelnik, G. Sigl, H. H. Silva Lopez, O. Sima, A. Śmiałkowski, R. Šmída, G. R. Snow, P. Sommers, J. Sorokin, H. Spinka, R. Squartini, Y. N. Srivastava, S. Stanic, J. Stapleton, J. Stasielak, M. Stephan, A. Stutz, F. Suarez, T. Suomijärvi, A. D. Supanitsky, T. Šuša, M. S. Sutherland, J. Swain, Z. Szadkowski, M. Szuba, A. Tapia, M. Tartare, O. Taşcău, C. G. Tavera Ruiz, R. Tcaciuc, N. T. Thao, D. Thomas, J. Tiffenberg, C. Timmermans, W. Tkaczyk, C. J. Todero Peixoto, G. Toma, L. Tomankova, B. Tomé, A. Tonachini, P. Travnicek, D. B. Tridapalli, G. Tristram, E. Trovato, M. Tueros, R. Ulrich, M. Unger, M. Urban, J. F. Valdés Galicia, I. Valiño, L. Valore, A. M. van den Berg, E. Varela, B. Vargas Cárdenas, J. R. Vázquez, R. A. Vázquez, D. Veberič, V. Verzi, J. Vicha, M. Videla, L. Villaseñor, H. Wahlberg, P. Wahrlich, O. Wainberg, D. Walz, A. A. Watson, M. Weber, K. Weidenhaupt, A. Weindl, F. Werner, S. Westerhoff, B. J. Whelan, A. Widom, G. Wieczorek, L. Wiencke, B. Wilczyńska, H. Wilczyński, M. Will, C. Williams, T. Winchen, M. Wommer, B. Wundheiler, T. Yamamoto a, T. Yapici, P. Younk, G. Yuan, A. Yushkov, B. Zamorano, E. Zas, D. Zavrtanik, M. Zavrtanik, I. Zaw h, A. Zepeda, Y. Zhu, M. Zimbres Silva, M. Ziolkowski, COLUCCIA, MARIA RITA, DE MITRI, Ivan, MARSELLA, GIOVANNI, MARTELLO, Daniele, PERRONE, Lorenzo, J. R., Hörandel for the Auger Collaboration, M., Ambrosio, Aramo, Carla, M., Cilmo, D'Urso, Domenico, Guarino, Fausto, Valore, Laura, J. R., Hörandel, P., Abreu, M., Aglietta, M., Ahler, E. J., Ahn, I. F. M., Albuquerque, D., Allard, I., Allekotte, J., Allen, P., Allison, A., Almela, J., Alvarez Castillo, J., Alvarez Muñiz, A., Aminaei, L., Anchordoqui, S., Andringa, T., Antičić, C., Aramo, E., Arganda, F., Arquero, H., Asorey, P., Assi, J., Aublin, M., Ave, M., Avenier, G., Avila, T., Bäcker, A. M., Badescu, M., Balzer, K. B., Barber, A. F., Barbosa, R., Bardenet, S. L. C., Barroso, B., Baughman f, J., Bäuml, J. J., Beatty, B. R., Becker, K. H., Becker, A., Bellétoile, J. A., Bellido, S., Benzvi, C., Berat, X., Bertou, P. L., Biermann, P., Billoir, F., Blanco, M., Blanco, C., Bleve, H., Blümer, M., Boháčová, D., Boncioli, C., Bonifazi, R., Bonino, N., Borodai, J., Brack, I., Brancu, P., Brogueira, W. C., Brown, R., Bruijn i, P., Buchholz, A., Bueno, R. E., Burton, K. S., Caballero Mora, B., Caccianiga, L., Caramete, R., Caruso, A., Castellina, O., Catalano, G., Cataldi, L., Cazon, R., Cester, J., Chauvin, S. H., Cheng, A., Chiavassa, J. A., Chinellato, J., Chirinos Diaz, J., Chudoba, R. W., Clay, Coluccia, MARIA RITA, R., Conceição, F., Contrera, H., Cook, M. J., Cooper, J., Coppen, A., Cordier, S., Coutu, C. E., Covault, A., Creusot, A., Cri, J., Cronin, A., Curutiu, S., Dagoret Campagne, R., Dallier, B., Daniel, S., Dasso, K., Daumiller, B. R., Dawson, R. M., de Almeida, M., De Domenico, C., De Donato, S. J., de Jong, G., De La Vega, W. J. M., de Mello Junior, J. R. T., de Mello Neto, DE MITRI, Ivan, V., de Souza, K. D., de Vrie, L., del Peral, M., del Río, O., Deligny, H., Dembinski, N., Dhital, C., Di Giulio, M. L., Díaz Castro, P. N., Diep, F., Diogo, C., Dobrigkeit, W., Docter, J. C., D'Olivo, P. N., Dong, A., Dorofeev, J. C., dos Anjo, M. T., Dova, D., D'Urso, I., Dutan, J., Ebr, R., Engel, M., Erdmann, C. O., Escobar, J., Espadanal, A., Etchegoyen, P., Facal San Lui, I., Fajardo Tapia, H., Falcke, G., Farrar, A. C., Fauth, N., Fazzini, A. P., Ferguson, B., Fick, A., Filevich, A., Filipčič, S., Fliescher, C. E., Fracchiolla, E. D., Fraenkel, O., Fratu, U., Fröhlich, B., Fuch, R., Gaior, R. F., Gamarra, S., Gambetta, B., García, S. T., Garcia Roca, D., Garcia Gamez, D., Garcia Pinto, A., Gascon, H., Gemmeke, P. L., Ghia, U., Giaccari, M., Giller, H., Gla, M. S., Gold, G., Golup, F., Gomez Albarracin, M., Gómez Berisso, P. F., Gómez Vitale, P., Gonçalve, D., Gonzalez, J. G., Gonzalez, B., Gookin, A., Gorgi, P., Gouffon, E., Grashorn, S., Grebe, N., Griffith, M., Grigat, A. F., Grillo, Y., Guardincerri, F., Guarino, G. P., Guede, A., Guzman, P., Hansen, D., Harari, T. A., Harrison, J. L., Harton, A., Haung, T., Hebbeker, D., Heck, A. E., Herve, C., Hojvat, N., Hollon, V. C., Holme, P., Homola, A., Horneffer, P., Horvath, M., Hrabovský, D., Huber, T., Huege, A., Insolia, F., Ionita, A., Italiano, C., Jarne, S., Jiraskova, M., Josebachuili, K., Kadija, K. H., Kampert, P., Karhan, P., Kasper, B., Kégl, B., Keilhauer, A., Keivani, J. L., Kelley, E., Kemp, R. M., Kieckhafer, H. O., Klage, M., Kleifge, J., Kleinfeller, J., Knapp, D. H., Koang, K., Kotera, N., Krohm, O., Krömer, D., Kruppke Hansen, F., Kuehn, D., Kuempel, J. K., Kulbartz, N., Kunka, G., La Rosa, C., Lachaud, D., Lahurd, L., Latronico, R., Lauer, P., Lautridou, S., Le Coz, M. S. A. B., Leão, D., Lebrun, P., Lebrun, M. A., Leigui de Oliveira, A., Letessier Selvon, I., Lhenry Yvon, K., Link, R., López, A., Lopez Agüera, K., Louedec, J., Lozano Bahilo, L., Lu, A., Lucero, M., Ludwig, H., Lyberi, M. C., Maccarone, C., Macolino, S., Maldera, D., Mandat, P., Mantsch, A. G., Mariazzi, J., Marin, V., Marin, I. C., Mari, H. R., Marquez Falcon, Marsella, Giovanni, Martello, Daniele, L., Martin, H., Martinez, O., Martínez Bravo, H. J., Mathe, J., Matthew, J. A. J., Matthew, G., Matthiae, D., Maurel, D., Maurizio, P. O., Mazur, G., Medina Tanco, M., Melissa, D., Melo, E., Menichetti, A., Menshikov, P., Mertsch, C., Meurer, S., Mićanović, M. I., Micheletti, I. A., Minaya, L., Miramonti, L., Molina Bueno, S., Mollerach, M., Monasor, D., Monnier Ragaigne, F., Montanet, B., Morale, C., Morello, E., Moreno, J. C., Moreno, M., Mostafá, C. A., Moura, M. A., Muller, G., Müller, M., Münchmeyer, R., Mussa, G., Navarra ‡, J. L., Navarro, S., Nava, P., Necesal, L., Nellen, A., Nelle, J., Neuser, P. T., Nhung, M., Niechciol, L., Niemietz, N., Nierstenhoefer, D., Nitz, D., Nosek, L., Nožka, J., Oehlschläger, A., Olinto, M., Ortiz, N., Pacheco, D., Pakk Selmi Dei, M., Palatka, J., Pallotta, N., Palmieri, G., Parente, E., Parizot, A., Parra, S., Pastor, T., Paul, M., Pech, J., Pękala, R., Pelayo, I. M., Pepe, Perrone, Lorenzo, R., Pesce, E., Petermann, S., Petrera, P., Petrinca, A., Petrolini, Y., Petrov, C., Pfendner, R., Piegaia, T., Pierog, P., Pieroni, M., Pimenta, V., Pirronello, M., Platino, M., Plum, V. H., Ponce, M., Pontz, A., Porcelli, P., Privitera, M., Prouza, E. J., Quel, S., Querchfeld, J., Rautenberg, O., Ravel, D., Ravignani, B., Revenu, J., Ridky, S., Riggi, M., Risse, P., Ristori, H., Rivera, V., Rizi, J., Robert, W., Rodrigues de Carvalho, G., Rodriguez, J., Rodriguez Martino, J., Rodriguez Rojo, I., Rodriguez Cabo, M. D., Rodríguez Fría, G., Ro, J., Rosado, T., Rossler, M., Roth, B., Rouillé d'Orfeuil, E., Roulet, A. C., Rovero, C., Rühle, A., Saftoiu, F., Salamida, H., Salazar, F., Salesa Greu, G., Salina, F., Sánchez, C. E., Santo, E., Santo, E. M., Santo, F., Sarazin, B., Sarkar, S., Sarkar, R., Sato, N., Scharf, V., Scherini, H., Schieler, P., Schiffer, A., Schmidt, O., Scholten, H., Schoorlemmer, J., Schovancova, P., Schovánek, F., Schröder, S., Schulte, D., Schuster, S. J., Sciutto, M., Scuderi, A., Segreto, M., Settimo, A., Shadkam, R. C., Shellard, I., Sidelnik, G., Sigl, H. H., Silva Lopez, O., Sima, A., Śmiałkowski, R., Šmída, G. R., Snow, P., Sommer, J., Sorokin, H., Spinka, R., Squartini, Y. N., Srivastava, S., Stanic, J., Stapleton, J., Stasielak, M., Stephan, A., Stutz, F., Suarez, T., Suomijärvi, A. D., Supanitsky, T., Šuša, M. S., Sutherland, J., Swain, Z., Szadkowski, M., Szuba, A., Tapia, M., Tartare, O., Taşcău, C. G., Tavera Ruiz, R., Tcaciuc, N. T., Thao, D., Thoma, J., Tiffenberg, C., Timmerman, W., Tkaczyk, C. J., Todero Peixoto, G., Toma, L., Tomankova, B., Tomé, A., Tonachini, P., Travnicek, D. B., Tridapalli, G., Tristram, E., Trovato, M., Tuero, R., Ulrich, M., Unger, M., Urban, J. F., Valdés Galicia, I., Valiño, L., Valore, A. M., van den Berg, E., Varela, B., Vargas Cárdena, J. R., Vázquez, R. A., Vázquez, D., Veberič, V., Verzi, J., Vicha, M., Videla, L., Villaseñor, H., Wahlberg, P., Wahrlich, O., Wainberg, D., Walz, A. A., Watson, M., Weber, K., Weidenhaupt, A., Weindl, F., Werner, S., Westerhoff, B. J., Whelan, A., Widom, G., Wieczorek, L., Wiencke, B., Wilczyńska, H., Wilczyński, M., Will, C., William, T., Winchen, M., Wommer, B., Wundheiler, T., Yamamoto a, T., Yapici, P., Younk, G., Yuan, A., Yushkov, B., Zamorano, E., Za, D., Zavrtanik, M., Zavrtanik, I., Zaw h, A., Zepeda, Y., Zhu, M., Zimbres Silva, and M., Ziolkowski

Subjects
Physics, business.industry, Astronomy, Astrophysical source, General Physics and Astronomy, Pierre Auger Observatory, Cosmic Ray, Particle detector, Cosmology, Radiation flux, Optics, Measuring instrument, Ultra-high-energy cosmic ray, business
Abstract

The Earth is exposed to a permanent rain of cosmic particles from outer space [1]. Most of the particles are fully ionised atomic nuclei, moving with relativistic energies. The bulk of them with energies up to 1017 eV originate within our Milky Way. They are most likely accel- erated in supernova remnants. Some particles have a thousand times higher energies, i.e., around 1020 eV. This corresponds to the kinetic energy of a tennis ball with a mass of 50 g and a velocity of 90 km/h

Published
2012
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39. L1

Author

G, Giannopoulos, G, Barucca, A, Kaidatzis, V, Psycharis, R, Salikhov, M, Farle, E, Koutsouflakis, D, Niarchos, A, Mehta, M, Scuderi, G, Nicotra, C, Spinella, S, Laureti, and G, Varvaro

Subjects
Article
Abstract

The fct L10-FeNi alloy is a promising candidate for the development of high performance critical-elements-free magnetic materials. Among the different materials, the Au-Cu-Ni alloy has resulted very promising; however, a detailed investigation of the effect of the buffer-layer composition on the formation of the hard FeNi phase is still missing. To accelerate the search of the best Au-Cu-Ni composition, a combinatorial approach based on High-Throughput (HT) experimental methods has been exploited in this paper. HT magnetic characterization methods revealed the presence of a hard magnetic phase with an out-of-plane easy-axis, whose coercivity increases from 0.49 kOe up to 1.30 kOe as the Au content of the Cu-Au-Ni buffer-layer decreases. Similarly, the out-of-plane magneto-crystalline anisotropy energy density increases from 0.12 to 0.35 MJ/m3. This anisotropy is attributed to the partial formation of the L10 FeNi phase induced by the buffer-layer. In the range of compositions we investigated, the buffer-layer structure does not change significantly and the modulation of the magnetic properties with the Au content in the combinatorial layer is mainly related to the different nature and extent of interlayer diffusion processes, which have a great impact on the formation and order degree of the L10 FeNi phase.

Published
2018

40. Frictional heterogeneities on carbonate-bearing normal faults: Insights from the Monte Maggio Fault, Italy

Author

Brett M. Carpenter, Marco M. Scuderi, Chris Marone, and Cristiano Collettini

Subjects
geography, geography.geographical_feature_category, Cataclasite, Lithology, Slip (materials science), Fault (geology), Elastic-rebound theory, Strike-slip tectonics, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Fault gouge, Earth and Planetary Sciences (miscellaneous), Aftershock, Seismology, Geology
Abstract

Observations of heterogeneous and complex fault slip are often attributed to the complexity of fault structure and/or spatial heterogeneity of fault frictional behavior. Such complex slip patterns have been observed for earthquakes on normal faults throughout central Italy, where many of the Mw 6 to 7 earthquakes in the Apennines nucleate at depths where the lithology is dominated by carbonate rocks. To explore the relationship between fault structure and heterogeneous frictional properties, we studied the exhumed Monte Maggio Fault, located in the northern Apennines. We collected intact specimens of the fault zone, including the principal slip surface and hanging wall cataclasite, and performed experiments at a normal stress of 10 MPa under saturated conditions. Experiments designed to reactivate slip between the cemented principal slip surface and cataclasite show a 3 MPa stress drop as the fault surface fails, then velocity-neutral frictional behavior and significant frictional healing. Overall, our results suggest that (1) earthquakes may readily nucleate in areas of the fault where the slip surface separates massive limestone and are likely to propagate in areas where fault gouge is in contact with the slip surface; (2) postseismic slip is more likely to occur in areas of the fault where gouge is present; and (3) high rates of frictional healing and low creep relaxation observed between solid fault surfaces could lead to significant aftershocks in areas of low stress drop.

Published
2014
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41. On the origin and evolution of electrical signals during frictional stick slip in sheared granular material

Author

Troy Shinbrot, Chris Marone, Demian M. Saffer, Marco M. Scuderi, and J. R. Leeman

Subjects
electromagnetic signals, electron holes, force chains, gouge friction, seismoelectric phenomena, stick slip, Geochemistry and Petrology, Geophysics, Earth and Planetary Sciences (miscellaneous), Space and Planetary Science, Slip (materials science), Granular material, Signal, Physics::Geophysics, Shear (geology), Earthquake rupture, Grain boundary, Force chain, Geology, Triboelectric effect
Abstract

Electromagnetic signals have been reported in association with geophysical phenomena including earthquakes, landslides, and volcanic events. Mechanisms that suggested to explain seismoelectrical signals include triboelectricity, piezoelectricity, streaming potentials, and the migration of electron holes, yet the origin of such phenomena remains poorly understood. We present results from laboratory experiments regarding the relationship between electrical and mechanical signals for frictional stick-slip events in sheared soda-lime glass bead layers. The results are interpreted in the context of lattice defect migration and granular force chain mechanics. During stick-slip events, we observe two distinct behaviors delineated by the attainment of a frictional stick-slip steady state. During initial shear loading, layers charge during stick-slip events and the potential of the system rises. After steady state stick-slip behavior is attained, the system begins to discharge. Coseismic signals are characterized by potential drops superimposed on a longer-term trend. We suggest that the observed signal is a convolution of two effects: charging of the forcing blocks and signals associated with the stress state of the material. The long-term charging of the blocks is accomplished by grain boundary movement during the initial establishment of force chain networks. Short-term signals associated with stick-slip events may originate from produced electron holes. Applied to tectonic faults, our results suggest that electrical signals generated during frictional failure may provide a way to monitor stress and the onset of earthquake rupture. Potential changes could produce detectable signals that may forecast the early stages of failure, providing a modest warning of the event.

Published
2014
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42. Physicochemical processes of frictional healing: Effects of water on stick-slip stress drop and friction of granular fault gouge

Author

Brett M. Carpenter, Chris Marone, and Marco M. Scuderi

Subjects
Materials science, Drop (liquid), Slip (materials science), Mechanics, Granular material, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Fault gouge, Earth and Planetary Sciences (miscellaneous), Shear stress, Geotechnical engineering, Direct shear test, Pressure solution, Contact area
Abstract

Understanding the micromechanical processes that dictate the evolution of fault strength during the seismic cycle is a fundamental problem in earthquake physics. We report on laboratory experiments that investigate the role of water during repetitive stick-slip frictional sliding, with particular emphasis on the grain-scale and atomic-scale mechanisms of frictional restrengthening (healing). Our experiments are designed to test underlying concepts of rate and state friction laws. We sheared layers of soda-lime glass beads in a double direct shear configuration at a constant normal stress of 5 MPa. Shear stress was applied via a constant displacement rate from 0.3 to 300 µm/s. During each experiment, relative air humidity (RH) was kept constant at values of 5, 50, or 100%. Our data show a systematic increase in maximum friction (μmax), stick-slip friction drop (Δμ), and frictional healing rate, with increasing RH. The highest values of interevent dilation occur at 100% RH. Postexperiment scanning electron microscope observations reveal details of contact junction processes, showing a larger grain-to-grain contact area at higher RH. We find that the evolution of contact area depends inversely on slip velocity and directly on RH. Our results illuminate the fundamental processes that dictate stick-slip frictional sliding and provide important constraints on the mechanisms of rate and state friction.

Published
2014
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43. A search for point sources of EeV neutrons

Author

P. Abreu, M. Aglietta, M. Ahlers, E.J. Ahn, I.F.M. Albuquerque, D. Allard, I. Allekotte, J. Allen, P. Allison, A. Almela, J. Alvarez Castillo, J. Alvarez-Muñiz, R. Alves Batista, M. Ambrosio, A. Aminaei, L. Anchordoqui, S. Andringa, T. Antičić, C. Aramo, E. Arganda, F. Arqueros, H. Asorey, P. Assis, J. Aublin, M. Ave, M. Avenier, G. Avila, A.M. Badescu, M. Balzer, K.B. Barber, A.F. Barbosa, R. Bardenet, S.L.C. Barroso, B. Baughman f, J. Bäuml, C. Baus, J.J. Beatty, K.H. Becker, A. Bellétoile, J.A. Bellido, S. BenZvi, C. Berat, X. Bertou, P.L. Biermann, P. Billoir, F. Blanco, M. Blanco, C. Bleve, H. Blümer, M. Boháčová, D. Boncioli, C. Bonifazi, R. Bonino, N. Borodai, J. Brack, I. Brancus, P. Brogueira, W.C. Brown, R. Bruijn i, P. Buchholz, A. Bueno, L. Buroker, R.E. Burton, K.S. Caballero-Mora, B. Caccianiga, L. Caramete, R. Caruso, A. Castellina, O. Catalano, G. Cataldi, L. Cazon, R. Cester, J. Chauvin, S.H. Cheng, A. Chiavassa, J.A. Chinellato, J. Chirinos Diaz, J. Chudoba, M. Cilmo, R.W. Clay, G. Cocciolo, L. Collica, M.R. Coluccia, R. Conceição, F. Contreras, H. Cook, M.J. Cooper, J. Coppens, A. Cordier, S. Coutu, C.E. Covault, A. Creusot, A. Criss, J. Cronin, A. Curutiu, S. Dagoret-Campagne, R. Dallier, B. Daniel, S. Dasso, K. Daumiller, B.R. Dawson, R.M. de Almeida, M. De Domenico, C. De Donato, S.J. de Jong, G. De La Vega, W.J.M. de Mello Junior, J.R.T. de Mello Neto, I. De Mitri, V. de Souza, K.D. de Vries, L. del Peral, M. del Río, O. Deligny, H. Dembinski, N. Dhital, C. Di Giulio, M.L. Díaz Castro, P.N. Diep, F. Diogo, C. Dobrigkeit, W. Docters, J.C. D'Olivo, P.N. Dong, A. Dorofeev, J.C. dos Anjos, M.T. Dova, D. D'Urso, I. Dutan, J. Ebr, R. Engel, M. Erdmann, C.O. Escobar, J. Espadanal, A. Etchegoyen, P. Facal San Luis, H. Falcke, K. Fang, G. Farrar, A.C. Fauth, N. Fazzini, A.P. Ferguson, B. Fick, J.M. Figueira, A. Filevich, A. Filipčič, S. Fliescher, C.E. Fracchiolla, E.D. Fraenkel!, O. Fratu, U. Fröhlich, B. Fuchs, R. Gaior, R.F. Gamarra, S. Gambetta, B. García, S.T. Garcia Roca, D. Garcia-Gamez, D. Garcia-Pinto, G. Garilli, A. Gascon Bravo, H. Gemmeke, P.L. Ghia, M. Giller, J. Gitto, H. Glass, M.S. Gold, G. Golup, F. Gomez Albarracin, M. Gómez Berisso, P.F. Gómez Vitale, P. Gonçalves, J.G. Gonzalez, B. Gookin, A. Gorgi, P. Gouffon, E. Grashorn, S. Grebe, N. Griffith, A.F. Grillo, Y. Guardincerri, F. Guarino, G.P. Guedes, P. Hansen, D. Harari, T.A. Harrison, J.L. Harton, A. Haungs, T. Hebbeker, D. Heck, A.E. Herve, C. Hojvat, N. Hollon, V.C. Holmes, P. Homola, J.R. Hörandel, P. Horvath, M. Hrabovský, D. Huber, T. Huege, A. Insolia, F. Ionita, A. Italiano, S. Jansen, C. Jarne, S. Jiraskova, M. Josebachuili, K. Kadija, K.H. Kampert, P. Karhan, P. Kasper, I. Katkov, B. Kégl, B. Keilhauer, A. Keivani, J.L. Kelley, E. Kemp, R.M. Kieckhafer, H.O. Klages, M. Kleifges, J. Kleinfeller, J. Knapp, D.-H. Koang, K. Kotera, N. Krohm, O. Krömer, D. Kruppke-Hansen, D. Kuempel, J.K. Kulbartz, N. Kunka, G. La Rosa, C. Lachaud, D. LaHurd, L. Latronico, R. Lauer, P. Lautridou, S. Le Coz, M.S.A.B. Leão, D. Lebrun, P. Lebrun, M.A. Leigui de Oliveira, A. Letessier-Selvon, I. Lhenry-Yvon, K. Link, R. López, A. Lopez Agüera, K. Louedec, J. Lozano Bahilo, L. Lu, A. Lucero, M. Ludwig, H. Lyberis, M.C. Maccarone, C. Macolino, S. Maldera, J. Maller, D. Mandat, P. Mantsch, A.G. Mariazzi, J. Marin, V. Marin, I.C. Maris, H.R. Marquez Falcon, G. Marsella, D. Martello, L. Martin, H. Martinez, O. Martínez Bravo, D. Martraire, J.J. Masías Meza, H.J. Mathes, J. Matthews, J.A.J. Matthews, G. Matthiae, D. Maurel, D. Maurizio, P.O. Mazur, G. Medina-Tanco, M. Melissas, D. Melo, E. Menichetti, A. Menshikov, P. Mertsch, C. Meurer, R. Meyhandan, S. Mićanović, M.I. Micheletti, I.A. Minaya, L. Miramonti, L. Molina-Bueno, S. Mollerach, M. Monasor, D. Monnier Ragaigne, F. Montanet, B. Morales, C. Morello, E. Moreno, J.C. Moreno, M. Mostafá, C.A. Moura, M.A. Muller, G. Müller, M. Münchmeyer, R. Mussa, G. Navarra ‡, J.L. Navarro, S. Navas, P. Necesal, L. Nellen, A. Nelles, J. Neuser, P.T. Nhung, M. Niechciol, L. Niemietz, N. Nierstenhoefer, D. Nitz, D. Nosek, L. Nožka, J. Oehlschläger, A. Olinto, M. Ortiz, N. Pacheco, D. Pakk Selmi-Dei, M. Palatka, J. Pallotta, N. Palmieri, G. Parente, E. Parizot, A. Parra, S. Pastor, T. Paul, M. Pech, J. Pękala, R. Pelayo, I.M. Pepe, L. Perrone, R. Pesce, E. Petermann, S. Petrera, A. Petrolini, Y. Petrov, C. Pfendner, R. Piegaia, T. Pierog, P. Pieroni, M. Pimenta, V. Pirronello, M. Platino, M. Plum, V.H. Ponce, M. Pontz, A. Porcelli, P. Privitera, M. Prouza, E.J. Quel, S. Querchfeld, J. Rautenberg, O. Ravel, D. Ravignani, B. Revenu, J. Ridky, S. Riggi, M. Risse, P. Ristori, H. Rivera, V. Rizi, J. Roberts, W. Rodrigues de Carvalho, G. Rodriguez, I. Rodriguez Cabo, J. Rodriguez Martino, J. Rodriguez Rojo, M.D. Rodríguez-Frías, G. Ros, J. Rosado, T. Rossler, M. Roth, B. Rouillé-d'Orfeuil, E. Roulet, A.C. Rovero, C. Rühle, A. Saftoiu, F. Salamida, H. Salazar, F. Salesa Greus, G. Salina, F. SÃ! ¡nchez, C.E. Santo, E. Santos, E.M. Santos, F. Sarazin, B. Sarkar, S. Sarkar, R. Sato, N. Scharf, V. Scherini, H. Schieler, P. Schiffer, A. Schmidt, O. Scholten, H. Schoorlemmer, J. Schovancova, P. Schovánek, F. Schröder, S. Schulte, D. Schuster, S.J. Sciutto, M. Scuderi, A. Segreto, M. Settimo, A. Shadkam, R.C. Shellard, I. Sidelnik, G. Sigl, H.H. Silva Lopez, O. Sima, A. Śmiałkowski, R. Šmída, G.R. Snow, P. Sommers, J. Sorokin, H. Spinka, R. Squartini, Y.N. Srivastava, S. Stanic, J. Stapleton, J. Stasielak, M. Stephan, A. Stutz, F. Suarez, T. Suomijärvi, A.D. Supanitsky, T. Šuša, M.S. Sutherland, J. Swain, Z. Szadkowski, M. Szuba, A. Tapia, M. Tartare, O. Taşcău, R. Tcaciuc, N.T. Thao, D. Thomas, J. Tiffenberg, C. Timmermans, W. Tkaczyk, C.J. Todero Peixoto, G. Toma, L. Tomankova, B. Tomé, A. Tonachini, P. Travnicek, D.B. Tridapalli, G. Tristram, E. Trovato, M. Tueros, R. Ulrich, M. Unger, M. Urban, J.F. Valdés Galicia, I. Valiño, L. Valore, G. van Aar, A.M. van den Berg, A. van Vliet, E. Varela, B. Vargas Cárdenas, J.R. Vázquez, R.A. Vázquez, D. Veberič, V. Verzi, J. Vicha, M. Videla, L. Villaseñor, H. Wahlberg, P. Wahrlich, O. Wainberg, D. Walz, A.A. Watson, M. Weber, K. Weidenhaupt, A. Weindl, F. Werner, S. Westerhoff, B.J. Whelan, A. Widom, G. Wieczorek, L. Wiencke, B. Wilczyńska, H. Wilczyński, M. Will, C. Williams, T. Winchen, M. Wommer, B. Wundheiler, T. Yamamoto a, T. Yapici, P. Younk, G. Yuan, A. Yushkov, B. Zamorano Garcia, E. Zas, D. Zavrtanik, M. Zavrtanik, I. Zaw h, A. Zepeda b, J. Zhou, Y. Zhu, M. Zimbres Silva, M. Ziolkowski, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de l'Accélérateur Linéaire (LAL), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire SUBATECH Nantes (SUBATECH), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Nantes (UN)-Mines Nantes (Mines Nantes), Institut de Physique Nucléaire d'Orsay (IPNO), PIERRE AUGER, P. Abreu, M. Aglietta, M. Ahler, E.J. Ahn, I.F.M. Albuquerque, D. Allard, I. Allekotte, J. Allen, P. Allison, A. Almela, J. Alvarez Castillo, J. Alvarez-Muñiz, R. Alves Batista, M. Ambrosio, A. Aminaei, L. Anchordoqui, S. Andringa, T. Antičić, C. Aramo, E. Arganda, F. Arquero, H. Asorey, P. Assi, J. Aublin, M. Ave, M. Avenier, G. Avila, A.M. Badescu, M. Balzer, K.B. Barber, A.F. Barbosa, R. Bardenet, S.L.C. Barroso, B. Baughman f, J. Bäuml, C. Bau, J.J. Beatty, K.H. Becker, A. Bellétoile, J.A. Bellido, S. BenZvi, C. Berat, X. Bertou, P.L. Biermann, P. Billoir, F. Blanco, M. Blanco, C. Bleve, H. Blümer, M. Boháčová, D. Boncioli, C. Bonifazi, R. Bonino, N. Borodai, J. Brack, I. Brancu, P. Brogueira, W.C. Brown, R. Bruijn i, P. Buchholz, A. Bueno, L. Buroker, R.E. Burton, K.S. Caballero-Mora, B. Caccianiga, L. Caramete, R. Caruso, A. Castellina, O. Catalano, G. Cataldi, L. Cazon, R. Cester, J. Chauvin, S.H. Cheng, A. Chiavassa, J.A. Chinellato, J. Chirinos Diaz, J. Chudoba, M. Cilmo, R.W. Clay, G. Cocciolo, L. Collica, M.R. Coluccia, R. Conceição, F. Contrera, H. Cook, M.J. Cooper, J. Coppen, A. Cordier, S. Coutu, C.E. Covault, A. Creusot, A. Cri, J. Cronin, A. Curutiu, S. Dagoret-Campagne, R. Dallier, B. Daniel, S. Dasso, K. Daumiller, B.R. Dawson, R.M. de Almeida, M. De Domenico, C. De Donato, S.J. de Jong, G. De La Vega, W.J.M. de Mello Junior, J.R.T. de Mello Neto, I. De Mitri, V. de Souza, K.D. de Vrie, L. del Peral, M. del Río, O. Deligny, H. Dembinski, N. Dhital, C. Di Giulio, M.L. Díaz Castro, P.N. Diep, F. Diogo, C. Dobrigkeit, W. Docter, J.C. D'Olivo, P.N. Dong, A. Dorofeev, J.C. dos Anjo, M.T. Dova, D. D'Urso, I. Dutan, J. Ebr, R. Engel, M. Erdmann, C.O. Escobar, J. Espadanal, A. Etchegoyen, P. Facal San Lui, H. Falcke, K. Fang, G. Farrar, A.C. Fauth, N. Fazzini, A.P. Ferguson, B. Fick, J.M. Figueira, A. Filevich, A. Filipčič, S. Fliescher, C.E. Fracchiolla, E.D. Fraenkel!, O. Fratu, U. Fröhlich, B. Fuch, R. Gaior, R.F. Gamarra, S. Gambetta, B. García, S.T. Garcia Roca, D. Garcia-Gamez, D. Garcia-Pinto, G. Garilli, A. Gascon Bravo, H. Gemmeke, P.L. Ghia, M. Giller, J. Gitto, H. Gla, M.S. Gold, G. Golup, F. Gomez Albarracin, M. Gómez Berisso, P.F. Gómez Vitale, P. Gonçalve, J.G. Gonzalez, B. Gookin, A. Gorgi, P. Gouffon, E. Grashorn, S. Grebe, N. Griffith, A.F. Grillo, Y. Guardincerri, F. Guarino, G.P. Guede, P. Hansen, D. Harari, T.A. Harrison, J.L. Harton, A. Haung, T. Hebbeker, D. Heck, A.E. Herve, C. Hojvat, N. Hollon, V.C. Holme, P. Homola, J.R. Hörandel, P. Horvath, M. Hrabovský, D. Huber, T. Huege, A. Insolia, F. Ionita, A. Italiano, S. Jansen, C. Jarne, S. Jiraskova, M. Josebachuili, K. Kadija, K.H. Kampert, P. Karhan, P. Kasper, I. Katkov, B. Kégl, B. Keilhauer, A. Keivani, J.L. Kelley, E. Kemp, R.M. Kieckhafer, H.O. Klage, M. Kleifge, J. Kleinfeller, J. Knapp, D.-H. Koang, K. Kotera, N. Krohm, O. Krömer, D. Kruppke-Hansen, D. Kuempel, J.K. Kulbartz, N. Kunka, G. La Rosa, C. Lachaud, D. LaHurd, L. Latronico, R. Lauer, P. Lautridou, S. Le Coz, M.S.A.B. Leão, D. Lebrun, P. Lebrun, M.A. Leigui de Oliveira, A. Letessier-Selvon, I. Lhenry-Yvon, K. Link, R. López, A. Lopez Agüera, K. Louedec, J. Lozano Bahilo, L. Lu, A. Lucero, M. Ludwig, H. Lyberi, M.C. Maccarone, C. Macolino, S. Maldera, J. Maller, D. Mandat, P. Mantsch, A.G. Mariazzi, J. Marin, V. Marin, I.C. Mari, H.R. Marquez Falcon, G. Marsella, D. Martello, L. Martin, H. Martinez, O. Martínez Bravo, D. Martraire, J.J. Masías Meza, H.J. Mathe, J. Matthew, J.A.J. Matthew, G. Matthiae, D. Maurel, D. Maurizio, P.O. Mazur, G. Medina-Tanco, M. Melissa, D. Melo, E. Menichetti, A. Menshikov, P. Mertsch, C. Meurer, R. Meyhandan, S. Mićanović, M.I. Micheletti, I.A. Minaya, L. Miramonti, L. Molina-Bueno, S. Mollerach, M. Monasor, D. Monnier Ragaigne, F. Montanet, B. Morale, C. Morello, E. Moreno, J.C. Moreno, M. Mostafá, C.A. Moura, M.A. Muller, G. Müller, M. Münchmeyer, R. Mussa, G. Navarra ‡, J.L. Navarro, S. Nava, P. Necesal, L. Nellen, A. Nelle, J. Neuser, P.T. Nhung, M. Niechciol, L. Niemietz, N. Nierstenhoefer, D. Nitz, D. Nosek, L. Nožka, J. Oehlschläger, A. Olinto, M. Ortiz, N. Pacheco, D. Pakk Selmi-Dei, M. Palatka, J. Pallotta, N. Palmieri, G. Parente, E. Parizot, A. Parra, S. Pastor, T. Paul, M. Pech, J. Pękala, R. Pelayo, I.M. Pepe, L. Perrone, R. Pesce, E. Petermann, S. Petrera, A. Petrolini, Y. Petrov, C. Pfendner, R. Piegaia, T. Pierog, P. Pieroni, M. Pimenta, V. Pirronello, M. Platino, M. Plum, V.H. Ponce, M. Pontz, A. Porcelli, P. Privitera, M. Prouza, E.J. Quel, S. Querchfeld, J. Rautenberg, O. Ravel, D. Ravignani, B. Revenu, J. Ridky, S. Riggi, M. Risse, P. Ristori, H. Rivera, V. Rizi, J. Robert, W. Rodrigues de Carvalho, G. Rodriguez, I. Rodriguez Cabo, J. Rodriguez Martino, J. Rodriguez Rojo, M.D. Rodríguez-Fría, G. Ro, J. Rosado, T. Rossler, M. Roth, B. Rouillé-d'Orfeuil, E. Roulet, A.C. Rovero, C. Rühle, A. Saftoiu, F. Salamida, H. Salazar, F. Salesa Greu, G. Salina, F. SÃ! ¡nchez, C.E. Santo, E. Santo, E.M. 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J., Whelan, A., Widom, G., Wieczorek, L., Wiencke, B., Wilczyńska, H., Wilczyński, M., Will, C., William, T., Winchen, M., Wommer, B., Wundheiler, T., Yamamoto, T., Yapici, P., Younk, G., Yuan, A., Yushkov, B., Zamorano Garcia, E., Za, D., Zavrtanik, M., Zavrtanik, I., Zaw, A., Zepeda, J., Zhou, Y., Zhu, M., Zimbres Silva, M., Ziolkowski, APC - Astrophysique des Hautes Energies (APC - AHE), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Università di Bologna [Bologna] (UNIBO)-Università di Bologna [Bologna] (UNIBO), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), T., Antičić, C., Aramo, B., Baughman f, R., Bruijn i, M., Cilmo, Cocciolo, Giuseppe, Coluccia, MARIA RITA, DE MITRI, Ivan, D., D'Urso, K., Fang, E. D., Fraenkel!, G., Garilli, F., Guarino, Marsella, Giovanni, Martello, Daniele, S., Mićanović, G., Navarra ‡, J., Pękala, Perrone, Lorenzo, F., SÃ! ¡nchez, Scherini, Viviana, A., Śmiałkowski, L., Valore, T., Yamamoto a, I., Zaw h, A., Zepeda b, Research unit Nuclear & Hadron Physics, KVI - Center for Advanced Radiation Technology, and Research unit Astroparticle Physics

Subjects
Astronomy, Energy flux, Astrophysics, 01 natural sciences, 7. Clean energy, Neutron flux, Observatory, cosmic rays – Galaxy: disk – methods: data analysis, Neutron detection, 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Gamma ray, Astrophysics::Instrumentation and Methods for Astrophysics, ASTRONOMY, Pierre Auger Observatory, COSMIC-RAYS, Radiación cósmica, Ultra High Energy Cosmic Ray, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, MASSIVE BLACK-HOLE, Física nuclear, Pierre Auger Observatory, high-energy neutron sources, neutron flux limit, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Cosmic ray, Galaxia, Galaxy: disk, cosmic rays, 0103 physical sciences, high-energy neutron sources, Neutron, Cosmic-ray observatory, Ciencias Exactas, ANISOTROPY, 010308 nuclear & particles physics, GAMMA-RAYS, Análisis de datos, Física, Astronomy and Astrophysics, ASTROFÍSICA, neutron flux limit, methods: data analysis, NÊUTRONS, Space and Planetary Science, Ultra High Energy Cosmic Rays, Experimental High Energy Physics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], GALACTIC-CENTER
Abstract

A thorough search of the sky exposed at the Pierre Auger Cosmic Ray Observatory reveals no statistically significant excess of events in any small solid angle that would be indicative of a flux of neutral particles from a discrete source. The search covers from −90◦ to +15◦ in declination using four different energy ranges above 1 EeV (1018 eV). The method used in this search is more sensitive to neutrons than to photons. The upper limit on a neutron flux is derived for a dense grid of directions for each of the four energy ranges. These results constrain scenarios for the production of ultrahigh energy cosmic rays in the Galaxy., Facultad de Ciencias Exactas

Published
2012
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44. Measurement of the cosmic ray energy spectrum using hybrid events of the Pierre Auger Observatory

Author

M. Settimo, P. Abreu, M. Aglietta, M. Ahlers, E. J. Ahn, I. F. M. Albuquerque, D. Allard, I. Allekotte, J. Allen, P. Allison, A. Almela, J. Alvarez Castillo, J. Alvarez Muñiz, R. Alves Batista, M. Ambrosio, A. Aminaei, L. Anchordoqui, S. Andringa, T. Antičić, C. Aramo, E. Arganda, F. Arqueros, H. Asorey, P. Assis, J. Aublin, M. Ave, M. Avenier, G. Avila, A. M. Badescu, M. Balzer, K. B. Barber, A. F. Barbosa, R. Bardenet, S. L. C. Barroso, B. Baughman f, J. Bäuml, C. Baus, J. J. Beatty, K. H. Becker, A. Bellétoile, J. A. Bellido, S. BenZvi, C. Berat, X. Bertou, P. L. Biermann, P. Billoir, F. Blanco, M. Blanco, C. Bleve, H. Blümer, M. Boháčová, D. Boncioli, C. Bonifazi, R. Bonino, N. Borodai, J. Brack, I. Brancus, P. Brogueira, W. C. Brown, R. Bruijn i, P. Buchholz, A. Bueno, L. Buroker, R. E. Burton, K. S. Caballero Mora, B. Caccianiga, L. Caramete, R. Caruso, A. Castellina, O. Catalano, G. Cataldi, L. Cazon, R. Cester, J. Chauvin, S. H. Cheng, A. Chiavassa, J. A. Chinellato, J. Chirinos Diaz, J. Chudoba, M. Cilmo, R. W. Clay, L. Collica, R. Conceição, F. Contreras, H. Cook, M. J. Cooper, J. Coppens, A. Cordier, S. Coutu, C. E. Covault, A. Creusot, A. Criss, J. Cronin, A. Curutiu, S. Dagoret Campagne, R. Dallier, B. Daniel, S. Dasso, K. Daumiller, B. R. Dawson, R. M. de Almeida, M. De Domenico, C. De Donato, S. J. de Jong, G. De La Vega, W. J. M. de Mello Junior, J. R. T. de Mello Neto, V. de Souza, K. D. de Vries, L. del Peral, M. del Río, O. Deligny, H. Dembinski, N. Dhital, C. Di Giulio, M. L. Díaz Castro, P. N. Diep, F. Diogo, C. Dobrigkeit, W. Docters, J. C. D'Olivo, P. N. Dong, A. Dorofeev, J. C. dos Anjos, M. T. Dova, D. D'Urso, I. Dutan, J. Ebr, R. Engel, M. Erdmann, C. O. Escobar, J. Espadanal, A. Etchegoyen, P. Facal San Luis, H. Falcke, K. Fang, G. Farrar, A. C. Fauth, N. Fazzini, A. P. Ferguson, B. Fick, J. M. Figueira, A. Filevich, A. Filipčič, S. Fliescher, C. E. Fracchiolla, E. D. Fraenkel!, O. Fratu, U. Fröhlich, B. Fuchs, R. Gaior, R. F. Gamarra, S. Gambetta, B. García, S. T. Garcia Roca, D. Garcia Gamez, D. Garcia Pinto, G. Garilli, A. Gascon Bravo, H. Gemmeke, P. L. Ghia, M. Giller, J. Gitto, H. Glass, M. S. Gold, G. Golup, F. Gomez Albarracin, M. Gómez Berisso, P. F. Gómez Vitale, P. Gonçalves, J. G. Gonzalez, B. Gookin, A. Gorgi, P. Gouffon, E. Grashorn, S. Grebe, N. Griffith, A. F. Grillo, Y. Guardincerri, F. Guarino, G. P. Guedes, P. Hansen, D. Harari, T. A. Harrison, J. L. Harton, A. Haungs, T. Hebbeker, D. Heck, A. E. Herve, C. Hojvat, N. Hollon, V. C. Holmes, P. Homola, J. R. Hörandel, P. Horvath, M. Hrabovský, D. Huber, T. Huege, A. Insolia, F. Ionita, A. Italiano, S. Jansen, C. Jarne, S. Jiraskova, M. Josebachuili, K. Kadija, K. H. Kampert, P. Karhan, P. Kasper, I. Katkov, B. Kégl, B. Keilhauer, A. Keivani, J. L. Kelley, E. Kemp, R. M. Kieckhafer, H. O. Klages, M. Kleifges, J. Kleinfeller, J. Knapp, D. H. Koang, K. Kotera, N. Krohm, O. Krömer, D. Kruppke Hansen, D. Kuempel, J. K. Kulbartz, N. Kunka, G. La Rosa, C. Lachaud, D. LaHurd, L. Latronico, R. Lauer, P. Lautridou, S. Le Coz, M. S. A. B. Leão, D. Lebrun, P. Lebrun, M. A. Leigui de Oliveira, A. Letessier Selvon, I. Lhenry Yvon, K. Link, R. López, A. Lopez Agüera, K. Louedec, J. Lozano Bahilo, L. Lu, A. Lucero, M. Ludwig, H. Lyberis, M. C. Maccarone, C. Macolino, S. Maldera, J. Maller, D. Mandat, P. Mantsch, A. G. Mariazzi, J. Marin, V. Marin, I. C. Maris, H. R. Marquez Falcon, L. Martin, H. Martinez, O. Martínez Bravo, D. Martraire, J. J. Masías Meza, H. J. Mathes, J. Matthews, J. A. J. Matthews, G. Matthiae, D. Maurel, D. Maurizio, P. O. Mazur, G. Medina Tanco, M. Melissas, D. Melo, E. Menichetti, A. Menshikov, P. Mertsch, C. Meurer, R. Meyhandan, S. Mićanović, M. I. Micheletti, I. A. Minaya, L. Miramonti, L. Molina Bueno, S. Mollerach, M. Monasor, D. Monnier Ragaigne, F. Montanet, B. Morales, C. Morello, E. Moreno, J. C. Moreno, M. Mostafá, C. A. Moura, M. A. Muller, G. Müller, M. Münchmeyer, R. Mussa, G. Navarra ‡, J. L. Navarro, S. Navas, P. Necesal, L. Nellen, A. Nelles, J. Neuser, P. T. Nhung, M. Niechciol, L. Niemietz, N. Nierstenhoefer, D. Nitz, D. Nosek, L. Nožka, J. Oehlschläger, A. Olinto, M. Ortiz, N. Pacheco, D. Pakk Selmi Dei, M. Palatka, J. Pallotta, N. Palmieri, G. Parente, E. Parizot, A. Parra, S. Pastor, T. Paul, M. Pech, J. Pękala, R. Pelayo, I. M. Pepe, R. Pesce, E. Petermann, S. Petrera, A. Petrolini, Y. Petrov, C. Pfendner, R. Piegaia, T. Pierog, P. Pieroni, M. Pimenta, V. Pirronello, M. Platino, M. Plum, V. H. Ponce, M. Pontz, A. Porcelli, P. Privitera, M. Prouza, E. J. Quel, S. Querchfeld, J. Rautenberg, O. Ravel, D. Ravignani, B. Revenu, J. Ridky, S. Riggi, M. Risse, P. Ristori, H. Rivera, V. Rizi, J. Roberts, W. Rodrigues de Carvalho, G. Rodriguez, I. Rodriguez Cabo, J. Rodriguez Martino, J. Rodriguez Rojo, M. D. Rodríguez Frías, G. Ros, J. Rosado, T. Rossler, M. Roth, B. Rouillé d'Orfeuil, E. Roulet, A. C. Rovero, C. Rühle, A. Saftoiu, F. Salamida, H. Salazar, F. Salesa Greus, G. Salina, F. SÃ! ¡nchez, C. E. Santo, E. Santos, E. M. Santos, F. Sarazin, B. Sarkar, S. Sarkar, R. Sato, N. Scharf, V. Scherini, H. Schieler, P. Schiffer, A. Schmidt, O. Scholten, H. Schoorlemmer, J. Schovancova, P. Schovánek, F. Schröder, S. Schulte, D. Schuster, S. J. Sciutto, M. Scuderi, A. Segreto, A. Shadkam, R. C. Shellard, I. Sidelnik, G. Sigl, H. H. Silva Lopez, O. Sima, A. Śmiałkowski, R. Šmída, G. R. Snow, P. Sommers, J. Sorokin, H. Spinka, R. Squartini, Y. N. Srivastava, S. Stanic, J. Stapleton, J. Stasielak, M. Stephan, A. Stutz, F. Suarez, T. Suomijärvi, A. D. Supanitsky, T. Šuša, M. S. Sutherland, J. Swain, Z. Szadkowski, M. Szuba, A. Tapia, M. Tartare, O. Taşcău, R. Tcaciuc, N. T. Thao, D. Thomas, J. Tiffenberg, C. Timmermans, W. Tkaczyk, C. J. Todero Peixoto, G. Toma, L. Tomankova, B. Tomé, A. Tonachini, P. Travnicek, D. B. Tridapalli, G. Tristram, E. Trovato, M. Tueros, R. Ulrich, M. Unger, M. Urban, J. F. Valdés Galicia, I. Valiño, L. Valore, G. van Aar, A. M. van den Berg, A. van Vliet, E. Varela, B. Vargas Cárdenas, J. R. Vázquez, R. A. Vázquez, D. Veberič, V. Verzi, J. Vicha, M. Videla, L. Villaseñor, H. Wahlberg, P. Wahrlich, O. Wainberg, D. Walz, A. A. Watson, M. Weber, K. Weidenhaupt, A. Weindl, F. Werner, S. Westerhoff, B. J. Whelan, A. Widom, G. Wieczorek, L. Wiencke, B. Wilczyńska, H. Wilczyński, M. Will, C. Williams, T. Winchen, M. Wommer, B. Wundheiler, T. Yamamoto a, T. Yapici, P. Younk, G. Yuan, A. Yushkov, B. Zamorano Garcia, E. Zas, D. Zavrtanik, M. Zavrtanik, I. Zaw h, A. Zepeda b, J. Zhou, Y. Zhu, M. Zimbres Silva, M. Ziolkowski ., COCCIOLO, GIUSEPPE, COLUCCIA, MARIA RITA, DE MITRI, Ivan, MARSELLA, GIOVANNI, MARTELLO, Daniele, PERRONE, Lorenzo, Mariangela Settimo for the Pierre Auger, Collaboration, M., Ambrosio, C., Aramo, M., Cilmo, D'Urso, Domenico, Guarino, Fausto, Valore, Laura, M. Settimo, P. Abreu, M. Aglietta, M. Ahler, E.J. Ahn, I.F.M. Albuquerque, D. Allard, I. Allekotte, J. Allen, P. Allison, A. Almela, J. Alvarez Castillo, J. Alvarez-Muñiz, R. Alves Batista, M. Ambrosio, A. Aminaei, L. Anchordoqui, S. Andringa, T. Antičić, C. Aramo, E. Arganda, F. Arquero, H. Asorey, P. Assi, J. Aublin, M. Ave, M. Avenier, G. Avila, A.M. Badescu, M. Balzer, K.B. Barber, A.F. Barbosa, R. Bardenet, S.L.C. Barroso, B. Baughman f, J. Bäuml, C. Bau, J.J. Beatty, K.H. Becker, A. Bellétoile, J.A. Bellido, S. BenZvi, C. Berat, X. Bertou, P.L. Biermann, P. Billoir, F. Blanco, M. Blanco, C. Bleve, H. Blümer, M. Boháčová, D. Boncioli, C. Bonifazi, R. Bonino, N. Borodai, J. Brack, I. Brancu, P. Brogueira, W.C. Brown, R. Bruijn i, P. Buchholz, A. Bueno, L. Buroker, R.E. Burton, K.S. Caballero-Mora, B. Caccianiga, L. Caramete, R. Caruso, A. Castellina, O. Catalano, G. Cataldi, L. Cazon, R. Cester, J. Chauvin, S.H. Cheng, A. Chiavassa, J.A. Chinellato, J. Chirinos Diaz, J. Chudoba, M. Cilmo, R.W. Clay, G. Cocciolo, L. Collica, M.R. Coluccia, R. Conceição, F. Contrera, H. Cook, M.J. Cooper, J. Coppen, A. Cordier, S. Coutu, C.E. Covault, A. Creusot, A. Cri, J. Cronin, A. Curutiu, S. Dagoret-Campagne, R. Dallier, B. Daniel, S. Dasso, K. Daumiller, B.R. Dawson, R.M. de Almeida, M. De Domenico, C. De Donato, S.J. de Jong, G. De La Vega, W.J.M. de Mello Junior, J.R.T. de Mello Neto, I. De Mitri, V. de Souza, K.D. de Vrie, L. del Peral, M. del Río, O. Deligny, H. Dembinski, N. Dhital, C. Di Giulio, M.L. Díaz Castro, P.N. Diep, F. Diogo, C. Dobrigkeit, W. Docter, J.C. D'Olivo, P.N. Dong, A. Dorofeev, J.C. dos Anjo, M.T. Dova, D. D'Urso, I. Dutan, J. Ebr, R. Engel, M. Erdmann, C.O. Escobar, J. Espadanal, A. Etchegoyen, P. Facal San Lui, H. Falcke, K. Fang, G. Farrar, A.C. Fauth, N. Fazzini, A.P. Ferguson, B. Fick, J.M. Figueira, A. Filevich, A. Filipčič, S. Fliescher, C.E. Fracchiolla, E.D. Fraenkel!, O. Fratu, U. Fröhlich, B. Fuch, R. Gaior, R.F. Gamarra, S. Gambetta, B. García, S.T. Garcia Roca, D. Garcia-Gamez, D. Garcia-Pinto, G. Garilli, A. Gascon Bravo, H. Gemmeke, P.L. Ghia, M. Giller, J. Gitto, H. Gla, M.S. Gold, G. Golup, F. Gomez Albarracin, M. Gómez Berisso, P.F. Gómez Vitale, P. Gonçalve, J.G. Gonzalez, B. Gookin, A. Gorgi, P. Gouffon, E. Grashorn, S. Grebe, N. Griffith, A.F. Grillo, Y. Guardincerri, F. Guarino, G.P. Guede, P. Hansen, D. Harari, T.A. Harrison, J.L. Harton, A. Haung, T. Hebbeker, D. Heck, A.E. Herve, C. Hojvat, N. Hollon, V.C. Holme, P. Homola, J.R. Hörandel, P. Horvath, M. Hrabovský, D. Huber, T. Huege, A. Insolia, F. Ionita, A. Italiano, S. Jansen, C. Jarne, S. Jiraskova, M. Josebachuili, K. Kadija, K.H. Kampert, P. Karhan, P. Kasper, I. Katkov, B. Kégl, B. Keilhauer, A. Keivani, J.L. Kelley, E. Kemp, R.M. Kieckhafer, H.O. Klage, M. Kleifge, J. Kleinfeller, J. Knapp, D.-H. Koang, K. Kotera, N. Krohm, O. Krömer, D. Kruppke-Hansen, D. Kuempel, J.K. Kulbartz, N. Kunka, G. La Rosa, C. Lachaud, D. LaHurd, L. Latronico, R. Lauer, P. Lautridou, S. Le Coz, M.S.A.B. Leão, D. Lebrun, P. Lebrun, M.A. Leigui de Oliveira, A. Letessier-Selvon, I. Lhenry-Yvon, K. Link, R. López, A. Lopez Agüera, K. Louedec, J. Lozano Bahilo, L. Lu, A. Lucero, M. Ludwig, H. Lyberi, M.C. Maccarone, C. Macolino, S. Maldera, J. Maller, D. Mandat, P. Mantsch, A.G. Mariazzi, J. Marin, V. Marin, I.C. Mari, H.R. Marquez Falcon, G. Marsella, D. Martello, L. Martin, H. Martinez, O. Martínez Bravo, D. Martraire, J.J. Masías Meza, H.J. Mathe, J. Matthew, J.A.J. Matthew, G. Matthiae, D. Maurel, D. Maurizio, P.O. Mazur, G. Medina-Tanco, M. Melissa, D. Melo, E. Menichetti, A. Menshikov, P. Mertsch, C. Meurer, R. Meyhandan, S. Mićanović, M.I. Micheletti, I.A. Minaya, L. Miramonti, L. Molina-Bueno, S. Mollerach, M. Monasor, D. Monnier Ragaigne, F. Montanet, B. Morale, C. Morello, E. Moreno, J.C. Moreno, M. Mostafá, C.A. Moura, M.A. Muller, G. Müller, M. Münchmeyer, R. Mussa, G. Navarra ‡, J.L. Navarro, S. Nava, P. Necesal, L. Nellen, A. Nelle, J. Neuser, P.T. Nhung, M. Niechciol, L. Niemietz, N. Nierstenhoefer, D. Nitz, D. Nosek, L. Nožka, J. Oehlschläger, A. Olinto, M. Ortiz, N. Pacheco, D. Pakk Selmi-Dei, M. Palatka, J. Pallotta, N. Palmieri, G. Parente, E. Parizot, A. Parra, S. Pastor, T. Paul, M. Pech, J. Pękala, R. Pelayo, I.M. Pepe, L. Perrone, R. Pesce, E. Petermann, S. Petrera, A. Petrolini, Y. Petrov, C. Pfendner, R. Piegaia, T. Pierog, P. Pieroni, M. Pimenta, V. Pirronello, M. Platino, M. Plum, V.H. Ponce, M. Pontz, A. Porcelli, P. Privitera, M. Prouza, E.J. Quel, S. Querchfeld, J. Rautenberg, O. Ravel, D. Ravignani, B. Revenu, J. Ridky, S. Riggi, M. Risse, P. Ristori, H. Rivera, V. Rizi, J. Robert, W. Rodrigues de Carvalho, G. Rodriguez, I. Rodriguez Cabo, J. Rodriguez Martino, J. Rodriguez Rojo, M.D. Rodríguez-Fría, G. Ro, J. Rosado, T. Rossler, M. Roth, B. Rouillé-d'Orfeuil, E. Roulet, A.C. Rovero, C. Rühle, A. Saftoiu, F. Salamida, H. Salazar, F. Salesa Greu, G. Salina, F. SÃ! ¡nchez, C.E. Santo, E. Santo, E.M. Santo, F. Sarazin, B. Sarkar, S. Sarkar, R. Sato, N. Scharf, V. Scherini, H. Schieler, P. Schiffer, A. Schmidt, O. Scholten, H. Schoorlemmer, J. Schovancova, P. Schovánek, F. Schröder, S. Schulte, D. Schuster, S.J. Sciutto, M. Scuderi, A. Segreto, A. Shadkam, R.C. Shellard, I. Sidelnik, G. Sigl, H.H. Silva Lopez, O. Sima, A. Śmiałkowski, R. Šmída, G.R. Snow, P. Sommer, J. Sorokin, H. Spinka, R. Squartini, Y.N. Srivastava, S. Stanic, J. Stapleton, J. Stasielak, M. Stephan, A. Stutz, F. Suarez, T. Suomijärvi, A.D. Supanitsky, T. Šuša, M.S. Sutherland, J. Swain, Z. Szadkowski, M. Szuba, A. Tapia, M. Tartare, O. Taşcău, R. Tcaciuc, N.T. Thao, D. Thoma, J. Tiffenberg, C. Timmerman, W. Tkaczyk, C.J. Todero Peixoto, G. Toma, L. Tomankova, B. Tomé, A. Tonachini, P. Travnicek, D.B. Tridapalli, G. Tristram, E. Trovato, M. Tuero, R. Ulrich, M. Unger, M. Urban, J.F. Valdés Galicia, I. Valiño, L. Valore, G. van Aar, A.M. van den Berg, A. van Vliet, E. Varela, B. Vargas Cárdena, J.R. Vázquez, R.A. Vázquez, D. Veberič, V. Verzi, J. Vicha, M. Videla, L. Villaseñor, H. Wahlberg, P. Wahrlich, O. Wainberg, D. Walz, A.A. Watson, M. Weber, K. Weidenhaupt, A. Weindl, F. Werner, S. Westerhoff, B.J. Whelan, A. Widom, G. Wieczorek, L. Wiencke, B. Wilczyńska, H. Wilczyński, M. Will, C. William, T. Winchen, M. Wommer, B. Wundheiler, T. Yamamoto a, T. Yapici, P. Younk, G. Yuan, A. Yushkov, B. Zamorano Garcia, E. Za, D. Zavrtanik, M. Zavrtanik, I. Zaw h, A. Zepeda b, J. Zhou, Y. Zhu, M. Zimbres Silva, M. Ziolkowski ., M., Settimo, P., Abreu, M., Aglietta, M., Ahler, E. J., Ahn, I. F. M., Albuquerque, D., Allard, I., Allekotte, J., Allen, P., Allison, A., Almela, J., Alvarez Castillo, J., Alvarez Muñiz, R., Alves Batista, A., Aminaei, L., Anchordoqui, S., Andringa, T., Antičić, E., Arganda, F., Arquero, H., Asorey, P., Assi, J., Aublin, M., Ave, M., Avenier, G., Avila, A. M., Badescu, M., Balzer, K. B., Barber, A. F., Barbosa, R., Bardenet, S. L. C., Barroso, B., Baughman f, J., Bäuml, C., Bau, J. J., Beatty, K. H., Becker, A., Bellétoile, J. A., Bellido, S., Benzvi, C., Berat, X., Bertou, P. L., Biermann, P., Billoir, F., Blanco, M., Blanco, C., Bleve, H., Blümer, M., Boháčová, D., Boncioli, C., Bonifazi, R., Bonino, N., Borodai, J., Brack, I., Brancu, P., Brogueira, W. C., Brown, R., Bruijn i, P., Buchholz, A., Bueno, L., Buroker, R. E., Burton, K. S., Caballero Mora, B., Caccianiga, L., Caramete, R., Caruso, A., Castellina, O., Catalano, G., Cataldi, L., Cazon, R., Cester, J., Chauvin, S. H., Cheng, A., Chiavassa, J. A., Chinellato, J., Chirinos Diaz, J., Chudoba, R. W., Clay, Cocciolo, Giuseppe, L., Collica, Coluccia, MARIA RITA, R., Conceição, F., Contrera, H., Cook, M. J., Cooper, J., Coppen, A., Cordier, S., Coutu, C. E., Covault, A., Creusot, A., Cri, J., Cronin, A., Curutiu, S., Dagoret Campagne, R., Dallier, B., Daniel, S., Dasso, K., Daumiller, B. R., Dawson, R. M., de Almeida, M., De Domenico, C., De Donato, S. J., de Jong, G., De La Vega, W. J. M., de Mello Junior, J. R. T., de Mello Neto, DE MITRI, Ivan, V., de Souza, K. D., de Vrie, L., del Peral, M., del Río, O., Deligny, H., Dembinski, N., Dhital, C., Di Giulio, M. L., Díaz Castro, P. N., Diep, F., Diogo, C., Dobrigkeit, W., Docter, J. C., D'Olivo, P. N., Dong, A., Dorofeev, J. C., dos Anjo, M. T., Dova, D., D'Urso, I., Dutan, J., Ebr, R., Engel, M., Erdmann, C. O., Escobar, J., Espadanal, A., Etchegoyen, P., Facal San Lui, H., Falcke, K., Fang, G., Farrar, A. C., Fauth, N., Fazzini, A. P., Ferguson, B., Fick, J. M., Figueira, A., Filevich, A., Filipčič, S., Fliescher, C. E., Fracchiolla, E. D., Fraenkel!, O., Fratu, U., Fröhlich, B., Fuch, R., Gaior, R. F., Gamarra, S., Gambetta, B., García, S. T., Garcia Roca, D., Garcia Gamez, D., Garcia Pinto, G., Garilli, A., Gascon Bravo, H., Gemmeke, P. L., Ghia, M., Giller, J., Gitto, H., Gla, M. S., Gold, G., Golup, F., Gomez Albarracin, M., Gómez Berisso, P. F., Gómez Vitale, P., Gonçalve, J. G., Gonzalez, B., Gookin, A., Gorgi, P., Gouffon, E., Grashorn, S., Grebe, N., Griffith, A. F., Grillo, Y., Guardincerri, F., Guarino, G. P., Guede, P., Hansen, D., Harari, T. A., Harrison, J. L., Harton, A., Haung, T., Hebbeker, D., Heck, A. E., Herve, C., Hojvat, N., Hollon, V. C., Holme, P., Homola, J. R., Hörandel, P., Horvath, M., Hrabovský, D., Huber, T., Huege, A., Insolia, F., Ionita, A., Italiano, S., Jansen, C., Jarne, S., Jiraskova, M., Josebachuili, K., Kadija, K. H., Kampert, P., Karhan, P., Kasper, I., Katkov, B., Kégl, B., Keilhauer, A., Keivani, J. L., Kelley, E., Kemp, R. M., Kieckhafer, H. O., Klage, M., Kleifge, J., Kleinfeller, J., Knapp, D. H., Koang, K., Kotera, N., Krohm, O., Krömer, D., Kruppke Hansen, D., Kuempel, J. K., Kulbartz, N., Kunka, G., La Rosa, C., Lachaud, D., Lahurd, L., Latronico, R., Lauer, P., Lautridou, S., Le Coz, M. S. A. B., Leão, D., Lebrun, P., Lebrun, M. A., Leigui de Oliveira, A., Letessier Selvon, I., Lhenry Yvon, K., Link, R., López, A., Lopez Agüera, K., Louedec, J., Lozano Bahilo, L., Lu, A., Lucero, M., Ludwig, H., Lyberi, M. C., Maccarone, C., Macolino, S., Maldera, J., Maller, D., Mandat, P., Mantsch, A. G., Mariazzi, J., Marin, V., Marin, I. C., Mari, H. R., Marquez Falcon, Marsella, Giovanni, Martello, Daniele, L., Martin, H., Martinez, O., Martínez Bravo, D., Martraire, J. J., Masías Meza, H. J., Mathe, J., Matthew, J. A. J., Matthew, G., Matthiae, D., Maurel, D., Maurizio, P. O., Mazur, G., Medina Tanco, M., Melissa, D., Melo, E., Menichetti, A., Menshikov, P., Mertsch, C., Meurer, R., Meyhandan, S., Mićanović, M. I., Micheletti, I. A., Minaya, L., Miramonti, L., Molina Bueno, S., Mollerach, M., Monasor, D., Monnier Ragaigne, F., Montanet, B., Morale, C., Morello, E., Moreno, J. C., Moreno, M., Mostafá, C. A., Moura, M. A., Muller, G., Müller, M., Münchmeyer, R., Mussa, G., Navarra ‡, J. L., Navarro, S., Nava, P., Necesal, L., Nellen, A., Nelle, J., Neuser, P. T., Nhung, M., Niechciol, L., Niemietz, N., Nierstenhoefer, D., Nitz, D., Nosek, L., Nožka, J., Oehlschläger, A., Olinto, M., Ortiz, N., Pacheco, D., Pakk Selmi Dei, M., Palatka, J., Pallotta, N., Palmieri, G., Parente, E., Parizot, A., Parra, S., Pastor, T., Paul, M., Pech, J., Pękala, R., Pelayo, I. M., Pepe, Perrone, Lorenzo, R., Pesce, E., Petermann, S., Petrera, A., Petrolini, Y., Petrov, C., Pfendner, R., Piegaia, T., Pierog, P., Pieroni, M., Pimenta, V., Pirronello, M., Platino, M., Plum, V. H., Ponce, M., Pontz, A., Porcelli, P., Privitera, M., Prouza, E. J., Quel, S., Querchfeld, J., Rautenberg, O., Ravel, D., Ravignani, B., Revenu, J., Ridky, S., Riggi, M., Risse, P., Ristori, H., Rivera, V., Rizi, J., Robert, W., Rodrigues de Carvalho, G., Rodriguez, I., Rodriguez Cabo, J., Rodriguez Martino, J., Rodriguez Rojo, M. D., Rodríguez Fría, G., Ro, J., Rosado, T., Rossler, M., Roth, B., Rouillé d'Orfeuil, E., Roulet, A. C., Rovero, C., Rühle, A., Saftoiu, F., Salamida, H., Salazar, F., Salesa Greu, G., Salina, F., SÃ! ¡nchez, C. E., Santo, E., Santo, E. M., Santo, F., Sarazin, B., Sarkar, S., Sarkar, R., Sato, N., Scharf, V., Scherini, H., Schieler, P., Schiffer, A., Schmidt, O., Scholten, H., Schoorlemmer, J., Schovancova, P., Schovánek, F., Schröder, S., Schulte, D., Schuster, S. J., Sciutto, M., Scuderi, A., Segreto, A., Shadkam, R. C., Shellard, I., Sidelnik, G., Sigl, H. H., Silva Lopez, O., Sima, A., Śmiałkowski, R., Šmída, G. R., Snow, P., Sommer, J., Sorokin, H., Spinka, R., Squartini, Y. N., Srivastava, S., Stanic, J., Stapleton, J., Stasielak, M., Stephan, A., Stutz, F., Suarez, T., Suomijärvi, A. D., Supanitsky, T., Šuša, M. S., Sutherland, J., Swain, Z., Szadkowski, M., Szuba, A., Tapia, M., Tartare, O., Taşcău, R., Tcaciuc, N. T., Thao, D., Thoma, J., Tiffenberg, C., Timmerman, W., Tkaczyk, C. J., Todero Peixoto, G., Toma, L., Tomankova, B., Tomé, A., Tonachini, P., Travnicek, D. B., Tridapalli, G., Tristram, E., Trovato, M., Tuero, R., Ulrich, M., Unger, M., Urban, J. F., Valdés Galicia, I., Valiño, L., Valore, G., van Aar, A. M., van den Berg, A., van Vliet, E., Varela, B., Vargas Cárdena, J. R., Vázquez, R. A., Vázquez, D., Veberič, V., Verzi, J., Vicha, M., Videla, L., Villaseñor, H., Wahlberg, P., Wahrlich, O., Wainberg, D., Walz, A. A., Watson, M., Weber, K., Weidenhaupt, A., Weindl, F., Werner, S., Westerhoff, B. J., Whelan, A., Widom, G., Wieczorek, L., Wiencke, B., Wilczyńska, H., Wilczyński, M., Will, C., William, T., Winchen, M., Wommer, B., Wundheiler, T., Yamamoto a, T., Yapici, P., Younk, G., Yuan, A., Yushkov, B., Zamorano Garcia, E., Za, D., Zavrtanik, M., Zavrtanik, I., Zaw h, A., Zepeda b, J., Zhou, Y., Zhu, M., Zimbres Silva, M. Ziolkowski, ., Universität Siegen [Siegen], Dipartimento di Matematica e Fisica 'Ennio De Giorgi', Università del Salento [Lecce], Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO), Observatorio Pierre Auger, CNRS-INSU, Contrat europe : PIRSES-2009-GA-246806, Marie Curie-IRSES/EPLANET, European Project: 246806,EC:FP7:PEOPLE,FP7-PEOPLE-2009-IRSES,EPLANET(2011), KVI - Center for Advanced Radiation Technology, Research unit Astroparticle Physics, Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)

Subjects
FLUORESCENCE DETECTOR, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, Monte Carlo method, energy spectrum, FOS: Physical sciences, General Physics and Astronomy, Flux, Cosmic ray, EXTENSIVE AIR-SHOWERS, SURFACE DETECTOR, 01 natural sciences, Cosmic Ray, Auger, Pierre Auger Observatory, Monte Carlo simulations, ultra-high energy cosmic rays, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Observatory, 0103 physical sciences, RECONSTRUCTION, Fermilab, 010306 general physics, UHE Cosmic Rays, Monte Carlo, Energy Spectrum, TRIGGER, Nuclear Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, PACS: 96.50.S, 96.50.sb, 96.50.sd, 98.70.Sa, 010308 nuclear & particles physics, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Detector, Astrophysics::Instrumentation and Methods for Astrophysics, PROFILES, [PHYS.PHYS.PHYS-SPACE-PH]Physics [physics]/Physics [physics]/Space Physics [physics.space-ph], Experimental High Energy Physics, SIMULATION, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, ARRAY, Física nuclear, Astrophysics - High Energy Astrophysical Phenomena, RAIOS CÓSMICOS
Abstract

The energy spectrum of ultra-high energy cosmic rays above 10$^{18}$ eV is measured using the hybrid events collected by the Pierre Auger Observatory between November 2005 and September 2010. The large exposure of the Observatory allows the measurement of the main features of the energy spectrum with high statistics. Full Monte Carlo simulations of the extensive air showers (based on the CORSIKA code) and of the hybrid detector response are adopted here as an independent cross check of the standard analysis (Phys. Lett. B 685, 239 (2010)). The dependence on mass composition and other systematic uncertainties are discussed in detail and, in the full Monte Carlo approach, a region of confidence for flux measurements is defined when all the uncertainties are taken into account. An update is also reported of the energy spectrum obtained by combining the hybrid spectrum and that measured using the surface detector array., 13 pages, 12 figures

Published
2012
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45. Acoustic emission and microslip precursors to stick-slip failure in sheared granular material

Author

Michele Griffa, Jan Carmeliet, Robert A. Guyer, Marco M. Scuderi, Paul A. Johnson, Behrooz Ferdowsi, Chris Marone, Daniel T. Trugman, Bryan M. Kaproth, and P-Y. Le Bas

Subjects
Shearing (physics), 010504 meteorology & atmospheric sciences, Humidity, Slip (materials science), 010502 geochemistry & geophysics, Granular material, 01 natural sciences, Geophysics, Acoustic emission, Shear (geology), General Earth and Planetary Sciences, Geotechnical engineering, Composite material, 0105 earth and related environmental sciences
Abstract

[1] We investigate the physics of laboratory earthquake precursors in a biaxial shear configuration. We conduct laboratory experiments at room temperature and humidity in which we shear layers of glass beads under applied normal loads of 2–8 MPa and with shearing rates of 5–10 µm/s. We show that above ~ 3 MPa load, acoustic emission (AE), and shear microfailure (microslip) precursors exhibit an exponential increase in rate of occurrence, culminating in stick-slip failure. Precursors take place where the material is in a critical state—still modestly dilating, yet while the macroscopic frictional strength is no longer increasing.

Published
2013
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46. The effects of entrained debris on the basal sliding stability of a glacier

Author

Miriam Jackson, Marco M. Scuderi, Lucas K. Zoet, Richard B. Alley, Sridhar Anandakrishnan, Brett M. Carpenter, and Chris Marone

Subjects
Glacier ice accumulation, geography, geography.geographical_feature_category, Basal sliding, Glacier, Slip (materials science), Debris, Geophysics, Heat generation, Lubrication, Meltwater, Geomorphology, Geology, Earth-Surface Processes
Abstract

[1] New laboratory experiments exploring likely subglacial conditions reveal controls on the transition between stable sliding and stick-slip motion of debris-laden ice over rock, with implications for glacier behavior. Friction between a rock substrate and clasts in ice generates heat, which melts nearby ice to produce lubricating water. An increase in sliding speed or an increase in entrained debris raises heat generation and thus meltwater production. Unstable sliding is favored by low initial lubrication followed by rapid meltwater production in response to a velocity increase. Low initial lubrication can result from cold or drained conditions, whereas rapid increase in meltwater generation results from strong frictional heating caused by high sliding velocity or high debris loads. Strengthening of the interface (healing) during “stick” intervals between slip events occurs primarily through meltwater refreezing. When healing and unstable sliding are taken together, the experiments reported here suggest that stick-slip behavior is common from motion of debris-laden glacier ice over bedrock.

Published
2013
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47. Frictional stability and earthquake triggering during fluid pressure stimulation of an experimental fault

Author

Marco M. Scuderi, Cristiano Collettini, and Chris Marone

Subjects
010504 meteorology & atmospheric sciences, Aseismic creep, Slip (materials science), Induced seismicity, 010502 geochemistry & geophysics, 01 natural sciences, carbonates, creep experiments, dynamic instability, fluid pressure stimulation, frictional stability analysis, induced seismicity, geophysics, geochemistry and petrology, earth and planetary sciences, space and planetary science, Physics::Geophysics, Overpressure, Physics::Fluid Dynamics, Geophysics, Creep, Shear (geology), Space and Planetary Science, Geochemistry and Petrology, Fault gouge, Earth and Planetary Sciences (miscellaneous), Shear stress, Geotechnical engineering, human activities, Geology, 0105 earth and related environmental sciences
Abstract

It is widely recognized that the significant increase of M > 3.0 earthquakes in Western Canada and the Central United States is related to underground fluid injection. Following injection, fluid overpressure lubricates the fault and reduces the effective normal stress that holds the fault in place, promoting slip. Although, this basic physical mechanism for earthquake triggering and fault slip is well understood, there are many open questions related to induced seismicity. Models of earthquake nucleation based on rate- and state-friction predict that fluid overpressure should stabilize fault slip rather than trigger earthquakes. To address this controversy, we conducted laboratory creep experiments to monitor fault slip evolution at constant shear stress while the effective normal stress was systematically reduced via increasing fluid pressure. We sheared layers of carbonate-bearing fault gouge in a double direct shear configuration within a true-triaxial pressure vessel. We show that fault slip evolution is controlled by the stress state acting on the fault and that fluid pressurization can trigger dynamic instability even in cases of rate strengthening friction, which should favor aseismic creep. During fluid pressurization, when shear and effective normal stresses reach the failure condition, accelerated creep occurs in association with fault dilation; further pressurization leads to an exponential acceleration with fault compaction and slip localization. Our work indicates that fault weakening induced by fluid pressurization can overcome rate strengthening friction resulting in fast acceleration and earthquake slip. Our work points to modifications of the standard model for earthquake nucleation to account for the effect of fluid overpressure and to accurately predict the seismic risk associated with fluid injection.

Published
2017

48. Evolution of shear fabric in granular fault gouge from stable sliding to stick-slip and implications for fault slip mode

Author

Chris Marone, Marco M. Scuderi, Cecilia Viti, Cristiano Collettini, and Elisa Tinti

Subjects
geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, friction, fault mechanics, Geology, Geometry, Slip (materials science), earthquake, Fault (geology), 010502 geochemistry & geophysics, 01 natural sciences, Shear (geology), Fault gouge, Geotechnical engineering, Slip ratio, Shear zone, Slipping, Slip line field, 0105 earth and related environmental sciences
Abstract

Laboratory and theoretical studies provide insight into the mechanisms that control earthquake nucleation, when fault slip velocity is slow (v∼0.001 cm/s) to dynamic stick slip (v> 1 cm/s). The full range of fault slip modes was achieved by controlling the ratioK=k/kc, wherekis the elastic loading stiffness andkcis the fault zone critical rheologic stiffness. We show thatKcontrols the transition from slow-and-silent slip (K> 0.9) to fast-and-audible (K< 0.7,v= 3 cm/s, slip duration 0.003 s) slip events. Microstructural observations show that with accumulated strain, deformation concentrates in shear zones containing sharp shear planes made of nanoscale grains, which favor the development of frictional instabilities. Once this fabric is established, fault fabric does not change significantly with slip velocity, and fault slip behavior is mainly controlled by the interplay between the rheological properties of the slipping planes and fault zone stiffness.

Published
2017

49. Precursory changes in seismic velocity for the spectrum of earthquake failure modes

Author

Chris Marone, Marco M. Scuderi, Cristiano Collettini, Elisa Tinti, and G. Di Stefano

Subjects
geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Stiffness, Geophysics, Active fault, Low frequency, Fault (geology), 010502 geochemistry & geophysics, 01 natural sciences, Article, Physics::Geophysics, Tectonics, Creep, Earthquake simulation, 13. Climate action, Slow earthquake, medicine, General Earth and Planetary Sciences, medicine.symptom, earthquake damage, elasticity, failure mechanism, fault slip, laboratory method, seismic velocity, tectonic setting, Seismology, Geology, 0105 earth and related environmental sciences
Abstract

Temporal changes in seismic velocity during the earthquake cycle have the potential to illuminate physical processes associated with fault weakening and connections between the range of fault slip behaviours including slow earthquakes, tremor and low-frequency earthquakes1. Laboratory and theoretical studies predict changes in seismic velocity before earthquake failure2; however, tectonic faults fail in a spectrum of modes and little is known about precursors for those modes3. Here we show that precursory changes of wave speed occur in laboratory faults for the complete spectrum of failure modes observed for tectonic faults. We systematically altered the stiffness of the loading system to reproduce the transition from slow to fast stick–slip and monitored ultrasonic wave speed during frictional sliding. We find systematic variations of elastic properties during the seismic cycle for both slow and fast earthquakes indicating similar physical mechanisms during rupture nucleation. Our data show that accelerated fault creep causes reduction of seismic velocity and elastic moduli during the preparatory phase preceding failure, which suggests that real-time monitoring of active faults may be a means to detect earthquake precursors.

Published
2016

50. Avaliação da Taxa Diária de Evapotranspiração da Macrófita Aquática Zizaniopsis Bonariensis

Author

David Manuel Lelinho da Motta Marques, Carlos M. Scuderi, and Adolfo O.N. Villanueva

Subjects
Macrophytes, Evapotranspiration, Botany, Buried tanks, Zizaniopsis bonariensis, Aquatic Science, Biology, Evapotranspiração, Oceanography, Earth-Surface Processes, Water Science and Technology, Macrophyte
Abstract

O presente trabalho estima a taxa diária de evapotranspiração (ET) da macrófita aquática Zizaniopsis Bonariensis, espécie dominante em cobertura no Banhado do Taim, através do uso de tanques enterrados. Para isto foi montado um experimento, nas condições climáticas da região de Porto Alegre (RS), em que foram empregados três tanques: uma caixa com vegetação, uma caixa sem vegetação e um tanque classe A. Para medir o consumo de água nos tanques, foram utilizados sensores transmissores de pressão. No período avaliado (julho de 2004 até março de 2005) a taxa média diária de ET para Zizaniopsis Bonariensis na caixa com vegetação foi de 5,2 mm.dia-1, enquanto a taxa média diária de evaporação para a caixa sem vegetação foi de 3,1 mm.dia-1 e para o tanque classe A se obteve um valor de 3,8 mm.dia-1. A instalação conjunta do tanque classe A permitiu estabelecer razões de Evapotranspiração/evaporação para esta pesquisa, no período completo a razão foi de 1,37, ao passo que para as estações de inverno, primavera e verão foi de 0,95, 1,52 e 1,36, respectivamente. Enquanto o tanque classe A e a caixa sem vegetação consomem quantidades de água semelhantes, a caixa com vegetação consome mais água. The present study estimates the daily evapotranspiration (ET) rate of the aquatic macrophyte Zizaniopsis Bonariensis, a dominant species in the cover of the Taim Wetlands, by using buried tanks. An experiment was set up for this purpose according to the climatic conditions in the region of Porto Alegre (RS), where three tanks were used: a box with vegetation, a box without vegetation and a class A tank. Pressure transmitter sensors were used to measure water consumption in the tanks. During the period assessed (July 2004 to March 2005), the daily mean rate of ET for Zizniopsis Bonariensis in the box with vegetation was 5.2 mm. day-1, while the daily mean rate of evaporation for the box without vegetation was 3.1 mm. day-1 , and for the class A tank a value of 3.8 mm day-1. was obtained. The joint installation of the class A tank made it possible to establish evapotranspiration/evaporation ratios for this research. During the complete period the ratio was 1.37, whereas for the winter, spring and summer seasons it was 0.95, 1.53 and 1.36 respectively. While the class A tank and the box without vegetation consume similar amounts of water, the box with vegetation consumes more water.

Published
2012
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