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Bright bolides entering in the atmosphere announce the entrance of meter-sized meteoroids often surviving as meteorites reaching the ground. To be able to find them it is necessary to locate quickly the position of the final explosion. This is usually done using optical sensors, but the bolides produce shock waves that can be detected by infrasound stations and, after coupling to the ground, also by seismic stations. The increasing availability of tem-poral seismic station deployments and the gathering of the records on per-manent seismic networks can become a powerful tool to complement optical data, in particular for diurnal events or explosions located far from optical stations. We present here two examples of bolides exploding over NE Iberia that were reported in the Spanish Fireball and Meteorite Network (SPMN) cata-logue with magnitudes -12 and -17 and recorded by temporary seismic arrays deployed near their entry trajectory. The location of the final explosions has been derived from the seismic data using a simplistic hypothesis and the codes used systematically for earthquake location. Although locating accu-rately the origin point of sonic waves is a complex task, our approach allows getting a quick location of the explosion location, with errors estimated in few kilometers, that appears as a useful tool to better define the search zone for eventual meteorites

Recently, under the umbrella of a public-private collaboration project (CPP2021-009072), Atalaya Riotinto Minera S-L. and the CSIC through its institutes IGEO-Madrid and Geo3BCN-Barcelona, have undertaken an ambitious and innovative initiative to validate the applicability of state-of-the-art monitoring and prospecting systems for better tracking of deformations that may occur in the mine¿s environment and to study the petrophysical properties and 3D structure of the mine subsurface. In this work, we present the results of machine learning (ML) models developed to predict various physical properties of rock (PPR) for classifying main lithologies. This analysis is based on over a thousand surface rock samples and nine wells with lithology descriptions and density logs. These data sets have allowed us to characterize the main geological units and formations comprising the subsurface of the Riotinto (RT) mine. A quality control process was applied to the PPR database through lithology and intervals to identify and correct outlier values. Multi-Layer Perceptron neural networks were employed to predict these outliers. Various mathematical and supervised machine learning models were developed to understand and predict PPR associated with different geological units. The models were compared to identify the most efficient and stable one. Additionally, new machine learning models were implemented to predict lithofacies based on PPR. These models were then used to predict PPR and classify lithofacies in wells within a mining site. The results suggest that machine learning-based PPR prediction reduces uncertainty, providing a clearer understanding of the anisotropic characteristics of geological units. Apparent density, total porosity, and P-wave velocity properties were found to predict lithofacies with an accuracy of approximately 80%. In conclusion, this advancement not only redefines the precision with which lithofacies can be identified in the Riotinto mine but also estab

The potential of different ambient noise methodologies to map the geometry of a small-scale sedimentary basin has been tested using data acquired in the Cerdanya Basin (eastern Pyrenees). We present results based on a 1-year long broad-band deployment covering a large part of the Eastern Pyrenees and a 2-month long high-density deployment covering the basin with interstation distances around 1.5 km. The explored techniques include autocorrelations, ambient noise Rayleigh wave tomography, horizontal-to-vertical spectral ratio, and band-pass filtered ambient noise amplitude mapping. The basement depth estimations retrieved from each of these approaches, based on independent datasets and different implicit assumptions, are consistent, showing that the deeper part of the basin is located in its central part, reaching depths of 600-700 m close to the Têt Fault trace bounding the Cerdanya Basin to the NE. The results show also that when high-density seismic data are available, HVSR and ambient noise amplitude analysis in a selected frequency band are useful tools to quickly map the basement of a sedimentary basin. On the other hand, surface wave tomography, more complex to obtain, provides detailed information on the 3D velocity structure. Besides this methodological aspect, our results help to improve the geological characterization of the Cerdanya Basin and will provide further constraints to refine the seismic risk maps of an area of relevant tourism and economic activity.

We present the characterization of the seismic ambient noise wavefield in the open-pit Riotinto mine (southern Spain), in the mainframe of a collaborative research project aiming to use the ambient noise wave field to monitor structural subsurface changes in near real-time. Noise characterization is based on a dense seismic network of 30 stations located along a 1-km long segment of a tailings dam. We first describe the most frequent transient signals detected, including local and distant earthquakes, blasting, and vehicles. The time variations in the amplitude of the 10-40 Hz frequency band are then used to define three phases of activity during the recording period. The highest amplitudes are directly related to the regrowth of the dam wall carried out to properly store the constantly increasing amount of tailings. In the third phase, the seismic noise is dominated by the deposition of tailings into the deposit, allowing the use of seismic data to monitor in detail the evolution of the deposition process. The detailed knowledge of the sources of noise in the Riotinto mine provides the basis for developing ambient noise seismic interferometry methods to monitor the physical properties of the subsurface of this and other open-pit mining areas.

In recent years there has been an increasing interest in studying proof systems stronger than Resolution, with the aim of building more efficient SAT solvers based on them. In defining these proof systems, we try to find a balance between the power of the proof system (the size of the proofs required to refute a formula) and the difficulty of finding the proofs. In this paper we consider the proof systems circular Resolution, Sherali-Adams, Nullstellensatz and Weighted Resolution and we study their relative power from a theoretical perspective. We prove that circular Resolution, Sherali-Adams and Weighted Resolution are polynomially equivalent proof systems. We also prove that Nullstellensatz is polynomially equivalent to a restricted version of Weighted Resolution. The equivalences carry on also for versions of the systems where the coefficients/weights are expressed in unary., This work was supported by the Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación MCIN/AEI/10.13039/501100011033, Spain [grant numbers PID2019-109137GB-C21, PID2019-109137GB-C22, IJC2018-035334-I, PID2022-138506NB-C21], Peer Reviewed, Postprint (published version)

MaxSAT is the problem of finding an assignment satisfying the maximum number of clauses in a CNF formula. We consider a natural generalization of this problem to generic sets of polynomials and propose a weighted version of Polynomial Calculus to address this problem. Weighted Polynomial Calculus is a natural generalization of MaxSAT-Resolution and weighted Resolution that manipulates polynomials with coefficients in a finite field and either weights in N or Z. We show the soundness and completeness of these systems via an algorithmic procedure. Weighted Polynomial Calculus, with weights in N and coefficients in F2, is able to prove efficiently that Tseitin formulas on a connected graph are minimally unsatisfiable. Using weights in Z, it also proves efficiently that the Pigeonhole Principle is minimally unsatisfiable., This work was supported by the Spanish Agencia Estatal de Investigación with the grant PID2019-109137GB-C21/AEI/10.13039/501100011033 and the grant PID2019-109137GBC22/AEI/10.13039/501100011033. Ilario Bonacina: Partially supported by the grant IJC2018-035334-I/AEI/10.13039/501100011033. Maria Luisa Bonet: Partially supported by Simons Institute. Jordi Levy: Partially supported by Simons Institute., Peer Reviewed, Postprint (published version)

© The Authors 2015. Published by Oxford University Press on behalf of The Royal Astronomical Society. We deeply acknowledge the comments and suggestions made by the editor S. Goes. The reviewers N. Piana Agostti and an anonymous helped to improve the manuscript.We are grateful to the staff of the permanent networks for providing relevant data and to all members of the TopoIberia Seismic Working Group for their hard work in the acquisition and processing of field data. This work is part of the Consolider- Ingenio 2010 project TOPO-IBERIA (CSD2006- 00041). Additional funding was provided by projects CGL2006- 01171, CGL2008-01830, P09-RNM-5100 and CGL2012-31472. We acknowledge work on free software SAC (Goldstein et al. 1999) and GMT (Wessel & Smith 1998)., The Gibraltar arc and surrounding areas are a complex tectonic region and its tectonic evolution.since Miocene is still under debate. Knowledge of its lithospheric structure will help to.understand the mechanisms that produced extension and westward motion of the Alboran domain,.simultaneously withNW–SE compression driven by Africa–Europe plates convergence..We perform a P-wave receiver function analysis in which we analyse new data recorded at.83 permanent and temporary seismic broad-band stations located in the South of the Iberian.peninsula. These data are stacked and combined with data from a previous study in northern.Morocco to build maps of thickness and average vP/vS ratio for the crust, and cross-sections.to image the lithospheric discontinuities beneath the Gibraltar arc, the Betic and Rif Ranges.and their Iberian and Moroccan forelands. Crustal thickness values show strong lateral variations.in the southern Iberia peninsula, ranging from ∼19 to ∼46 km. The Variscan foreland is.characterized by a relatively flat Moho at ∼31 km depth, and an average vP/vS ratio of ∼1.72,.similar to other Variscan terranes, which may indicate that part of the lower crustal orogenic.root was lost. The thickest crust is found at the contact between the Alboran domain and the.External Zones of the Betic Range, while crustal thinning is observed southeastern Iberia.(down to 19 km) and in the Guadalquivir basin where the thinning at the Iberian paleomargin.could be still preserved. In the cross-sections, we see a strong change between the eastern.Betics, where the Iberian crust underthrusts and couples to the Alboran crust, and the western.Betics, where the underthrusting Iberian crust becomes partially delaminated and enters into.the mantle. The structures largely mirror those on the Moroccan side where a similar detachment.was observed in northern Morocco. We attribute a relatively shallow strong negativepolarity.discontinuity to the lithosphere-asthenosphere boundary. This mea, Ministerio de Economía y Competitividad (MINECO), Consolider-Ingenio 2010 (MINECO), Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub

Ambient seismic noise acquired in the Cerdanya Basin (eastern Pyrenees) is used to assess the capability of different methodologies to map the geometry of a small-scale sedimentary basin. We present results based on a 1-year-long broad-band deployment covering a large part of the eastern Pyrenees and a 2-month-long high-density deployment covering the basin with interstation distances around 1.5g€¯km. The explored techniques include autocorrelations, ambient noise Rayleigh wave tomography, horizontal-to-vertical-spectra ratio (HVSR) and band-pass-filtered ambient noise amplitude mapping. The basement depth estimations retrieved from each of these approaches, based on independent datasets and different implicit assumptions, are consistent, showing that the deeper part of the basin is located in its central part, reaching depths of 600-700g€¯m close to the Tet fault trace bounding the Cerdanya Basin to the NE. The overall consistency between the results from all the methodologies provides solid constraints to our basement depth estimation, although significant differences arise in some areas. The results also show that, when high-density seismic data are available, HVSR and ambient noise amplitude analysis in a selected frequency band are useful tools to quickly map the sedimentary 3D geometry. Beside this methodological aspect, our results help to improve the geological characterization of the Cerdanya Basin and will provide further constraints to refine the seismic risk maps of an area of relevant touristic and economic activity.

Using seismic data from 1,186 stations deployed across the westernmost Mediterranean, we construct a high-resolution 3-D radially anisotropic model from a joint inversion of receiver functions and Rayleigh and Love wave dispersions. The Rayleigh and Love data are extracted from both ambient noise interferograms and earthquake waveforms, and a new three-station ambient noise interferometry method is used to further improve the data coverage. The obtained crustal thickness map reproduces independently the Moho depth maps compiled from previous data, showing crustal roots beneath the Pyrenean-Cantabrian range and the Gibraltar Arc and thicker crust beneath the Variscan Iberian Massif than in the area affected by Alpine orogenesis. The Vsv crustal model outlines the Iberian Massif as a high shear wave velocity block and shows extremely low velocities in the Gulf of Cadiz and Gibraltar Arc. At mantle levels, a sharp boundary between the Aquitanean Basin and the Massif Central is imaged, with low Vsv beneath the Massif Central probably reflecting a remaining signature of the magma. To the south of Iberia, the geometry of the Alboran slab is captured by the model, while beneath the Atlas Mountains, widespread low Vsv and positive radial anisotropy is observed, favoring the edge-driven convection model explaining the lithospheric thinning. The most relevant contribution of this work is mapping, for the first time at this scale, the radial anisotropy anomalies at crustal level, with higher values observed in the Alpine Iberia, dominated by present-day extensional tectonics.

During the large-N MAUPASACQ passive seismic experiment in the foreland of the western Pyrenees (southwest France), an unusual swarm-type seismic sequence was serendipi-tously recorded in a normally quiet area. Thanks to the density of the deployment and the proximity of all events, it was possible to relocate the hypocenters with a very good relative accuracy through template matching, cross-correlation phase picks, and double-difference algorithm. The four-month seismic activity consists of more than 600 events with local magnitudes ranging between −1.4 and 2.1, clustered in an extremely small vol-ume, and rooted at 4 km depth. The sequence can be divided in two phases of similar durations and event occurrence rates, but of different magnitude–frequency distributions. The presence of an asperity is suggested by the relative abundance of stronger events during the second phase. Fine mapping suggests a small but clear geographic offset of a few tens of meters between the events of the two phases and a very slow migration suggesting a process involving fluids. Changes in the correlation matrices and waveforms of late arrivals at a specific station are also observed, arguing either (and again) for migration of the hypocenters or for changes in the propagation medium between the two phases. The geographical coincidence with the repeated observation of hydrogen leaks on the surface, almost above the swarm, suggests a connection through channels that could carry fluids.

Data acquired by a dense seismic network deployed in the Cerdanya basin (Eastern Pyrenees) is used to track the temporal and spatial evolution of meteorological events such as rainfall episodes or thunderstorms. Comparing seismic and meteorological data, we show that for frequencies above 40 Hz, the dominant source of seismic noise is rainfall and hence the amplitude of the seismic data can be used as a proxy of rainfall. The interstation distance of 1.5 km provides an unprecedented spatial resolution of the evolution of rainfall episodes along the basin. Two specific episodes, one dominated by stratiform rain and the second one dominated by convective rain, are analyzed in detail, using high resolution disdrometer data from a meteorological site near one of the seismic instruments. Seismic amplitude variations follow a similar evolution to radar reflectivity values, but in some stratiform precipitation cases, it differs from the radar-derived precipitation estimates in this region of abrupt topography where radar may suffer antenna beam blockage. Hence, we demonstrate the added value of seismic data to complement other sources of information such as rain-gauge or weather radar observations to describe the evolution of ground-level rainfall fields at high spatial and temporal resolution. The seismic power and the rainfall intensity have and exponential relationship and the periods with larger seismic power are coincident. The time periods with rain drops diameters exceeding 3.5 mm do not result in increased seismic amplitudes, suggesting that there is a threshold value from which seismic data are no longer proportional to the size of the drops. Thunderstorms can be identified by the recording of the sonic waves generated by thunders. We show that single thunders can be recorded to distances of a few tens of kilometers. As the propagation of these acoustic waves is expected to be strongly affected by parameters as air humidity, temperature variations or wind, the sei

En este trabajo se presenta dos proyectos de I+D+I pioneros en el sector minero, Minerva #smartgeocontrol y STONE, cuyo objetivo es el desarrollo e implementación de una plataforma de monitorización e interpretación multidisciplinar para aumentar la seguridad en los depósitos de residuos de la mina Riotinto. La plataforma integrará en tiempo real técnicas de monitorización geodésica y geotécnica clásicas, con técnicas innovadoras de satélite y sismología pasiva. Esta nueva plataforma web, originalmente diseñada para integrar datos de diferentes sensores, aún no ha sido implementada en ninguna mina en Europa. Los diferentes sensores que suministran datos, geodésicos (estaciones totales, sensores GNSS, ...), geotécnicos (piezómetros, inclinómetros, ...), ambientales y remotos, radar terrestre GB-SAR se conectarán a la plataforma y los datos obtenidos se mostrarán en tiempo real sobre un fondo geo-referenciado. Posteriormente, se integrarán con los resultados de las observaciones radar de satélite y ruido sísmico. Esto permitirá, de una forma muy intuitiva, interactuar con todos los sensores que están observando la mina. El principal objetivo de Atalaya Mining es llevar a cabo una transición digital innovadora hacia un control geodésico y geotécnico integral del entorno minero de Riotinto, favoreciendo la transición hacia la "minería inteligente", aumentando la seguridad de las estructuras y las personas en la operación minera.

Data acquired by broadband seismic stations distributed around the world are used to document the exceptionally long duration signal from the tsunami-associated gravity wave that followed the January 2022 Hunga-Tonga eruption. The first arrivals of this wave, with a frequency of around 2 mHz, are recorded at the time the tsunami arrives to each station, but the highest recorded frequencies, which reach 40 mHz, arrive 5 days later at some sites, following the prediction of a gravity wave originating at the Hunga-Tonga region and traveling in deep water. This dispersive signal is detected in most of the stations located in the Pacific Ocean basin and its coasts, but also in the Indian Ocean, Antarctica, and some stations in North America located hundreds of kilometers from the coastline. The signal is compared with the data gathered after earthquakes that have produced large tsunamis, showing that the seismic records from the Hunga-Tonga eruption are very different. Following the hypothesis pointed out by Omira et al 2023, we propose that the origin of this exceptional characteristic is due to the interaction between the tsunami and atmospheric waves that travel a little faster

A new high-resolution azimuthally anisotropic Vs model beneath the westernmost Mediterranean is constructed based on Rayleigh wave dispersions obtained from 1186 broadband seismic stations. The model reveals several prominent features, including: (1) Anisotropy beneath Iberia inferred from surface waves is generally consistent with the results independently deduced from the analysis of SKS splitting, with fast velocity directions aligned close to E-W in most of the investigated area. (2) Vertically coherent mantle deformation is found across the vast majority part of the westernmost Mediterranean, namely, lithospheric deformation is coupled with the underlying asthenosphere. (3) Two anisotropic mantle layers are required to fit the data in a region in central Iberia, including part of the Duero and Tagus basins and the Central System. This is interpreted as denoting deformation in the mantle lithosphere related to the Alpine compressional regime. (4) The anisotropy in the Alboran Basin is complex and can be related to a deflected mantle flow pattern around the Alboran slab.

The January 15th 2022 eruption of the Hunga-Tonga volcano was associated to one of the highest energy volcanic explosions of the past few decades. Here we present a compilation of data from global seismic networks to explore three main topics: the time evolution of the eruption, the propagation of the atmospheric waves around the Earth and the low-frequency, long-lasting seismic signals worldwide after the main event. We find that the eruption started around 04:00, included two large explosions at 05:30 and 08:25 and produced atmospheric waves which circled the Earth more than two times during a time span of 3.5 days and were detected seismically. We also identify very low frequency signals, detected over several hours, which we interpret as resulting from the excitation of Earth normal modes. To our knowledge, there are no previous examples of atmospheric-solid Earth coupling over such a long time interval and only two examples of normal mode excitation following volcanic eruptions.

Bright bolides entering in the atmosphere announce the entrance of meter-sized meteoroids often surviving as meteorites reaching the ground. To be able to find them it is necessary to locate quickly the position of the final explosion. This is usually done using optical sensors, but the bolides produce shock waves that can be detected by infrasound stations and, after coupling to the ground, also by seismic stations. The increasing availability of temporal seismic station deployments and the gathering of the records on permanent seismic networks can become a powerful tool to complement optical data, in particular for diurnal events or explosions located far from optical stations. We present here two examples of bolides exploding over NE Iberia that were reported in the Spanish Fireball and Meteorite Network (SPMN) catalogue with magnitudes -12 and -17 and recorded by temporary seismic arrays deployed near their entry trajectory. The location of the final explosions has been derived from the seismic data using a simplistic hypothesis and the codes used systematically for earthquake location. Although locating accurately the origin point of sonic waves is a complex task, our approach allows getting a quick location of the explosion location, with errors estimated in few kilometers, that appears as a useful tool to better define the search zone for eventual meteorites.