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11 results on '"Pauchet, H"'

4. An active source seismo-acoustic experiment using tethered balloons to validate instrument concepts and modelling tools for atmospheric seismology.

Author

Garcia, R F, Martire, L, Chaigneau, Y, Cadu, A, Mimoun, D, Bassas Portus, M, Sournac, A, Sylvander, M, Pauchet, H, Benahmed, S, and Martin, R

Subjects
SEISMIC waves, SOUND waves, ATMOSPHERIC models, ATMOSPHERIC acoustics, ACOUSTIC measurements, PLANETARY interiors, ACOUSTIC emission testing, INFRASONIC waves
Abstract

The measurements of acoustic waves created by a quake are of great interest for planets with hot and dense atmospheres, like Venus, because surface deployments of seismometers will last only a few hours, whereas freeflying balloons could fly many days. Infrasound sensors can also be used to constrain subsurface properties during active seismic experiments. This study presents a controlled source seismo-acoustic experiment using infrasonic sensors and accelerometers mounted on a tethered helium balloon. Both the acoustic waves generated below the balloon by seismic surface waves, and the ones generated by strong ground motions above the seismic source are clearly observed and separated on the records of the various instruments. This data set allows various validations and investigations. First, it validates the ground to air coupling theory and our numerical modelling tools. Then, it allows us to demonstrate that antenna processing of infrasound sensors deployed below the balloon can estimate the arrival incidence angle of the acoustic waves within 10°. Finally, a polarization analysis of the accelerometers taped on the balloon envelope is presented. It demonstrates that accelerometer records are strongly dependent on their location on the balloon due to its deformations and rotations. However, the different acoustic signals can be distinguished through their polarization, and a best sensor location is estimated at the bottom of the balloon envelope. These results are a first step towards detecting and locating seismic activity using airborne acoustic sensors on Venus and elsewhere. However, some observations of earthquake signals in a more realistic geometry are still missing. [ABSTRACT FROM AUTHOR]

Published
2021
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6. The Pyrenean architecture as revealed by teleseismic P-to-S converted waves recorded along two dense transects

Author

Chevrot, Sébastien, Sylvander, Matthieu, Diaz, Jordi, Ruiz, Mario, Paul, Anne, Cougoulat, Glenn, Péquegnat, Catherine, Wolyniec, David, Delmas, P., Grimaud, F., Benahmed, S., Pauchet, H., de Saint Blanquat, Michel, Lagabrielle, Yves, Manatschal, G., Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Consejo Superior de Investigaciones Científicas [Spain] (CSIC), Institut des Sciences de la Terre (ISTerre), Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-PRES Université de Grenoble-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Géosciences Environnement Toulouse (GET), Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Institut de physique du globe de Strasbourg (IPGS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), ANR-09-BLAN-0229,PYROPE(2009), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), Ondes et Structures (Isterre), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales [Toulouse] (CNES), Université de Rennes 1 (UR1), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Shear waves, Rift, Seismic tomography, 010504 meteorology & atmospheric sciences, Subduction, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Continental tectonics: compressional, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Crust, 010502 geochemistry & geophysics, 01 natural sciences, Tectonics, Geophysics, Dynamics of lithosphere and mantle, Geochemistry and Petrology, Lithosphere, [SDU]Sciences of the Universe [physics], compressional [Continental tectonics], 14. Life underwater, Transect, Seismology, Geology, 0105 earth and related environmental sciences
Abstract

© The Authors 2014. Between 2011 and 2013, two dense transects were deployed across the central and western Pyrenees to get better constraints on the deep lithospheric architecture and discriminate the competing models of the structure and formation of the Pyrenees. Each transect recorded the regional and global seismicity during a period of approximately 1 yr. Here, we exploit the records of teleseismic compressional waves and of their conversions to shear waves on internal discontinuities in order to map lithospheric interfaces beneath the two transects. The migrated sections, obtained by performing common conversion point stacks, are in remarkable agreement with the results of the ECORS-Pyrenees and ECORS-Arzacq deep seismic surveys. However, the migrations of converted waves reveal new details of the deep lithospheric architecture that could not be seen with the active source experiments. The new images provide clear and definite evidence for the subduction of a thinned Iberian crust down to at least ~70 km depth, a result that has important implications for the formation of the Pyrenees. The subduction of the Iberian lithosphere leads to reconsider the amount of convergence between Iberia and Europe during the Cenozoic. A recent regional P-wave tomography, relying on the data of the PYROPE and IBERARRAY temporary experiments, revealed the segmentation of lithospheric structures by inherited Hercynian NE-SW transfer faults that were reactivated during the Albian rifting. Ourmigration images are consistent with this model, and give further support to the idea that the Pyrenees were produced by the tectonic inversion of a segmented hyperextended rift that was buried by subduction beneath the European Plate., The PYROPE experiment was supported by the French Research Agency ANR blanc programme (project PYROPE, ANR-09-BLAN-0229). We also acknowledge SISMOB, the French seismic mobile pool (a component of the RESIF consortium), for providing us with the seismological instrumentation for the temporary deployments. RESIF (http://portal.resif.fr/ ) is a national Research Infrastructure, recognized as such by the French Ministry of Higher Education and Research. RESIF is managed by the RESIF Consortium, composed of 18 Research Institutions and Universities in France. RESIF additionally supported by a public grant overseen by the French National Research Agency (ANR) as part of the ‘Investissements d’Avenir’ programme (reference: ANR-11-EQPX-0040) and the French Ministry of Ecology, Sustainable Development and Energy

Published
2015

7. Absolute earthquake locations using 3-D versus 1-D velocity models below a local seismic network: example from the Pyrenees.

Author

Theunissen, T., Chevrot, S., Sylvander, M., Monteiller, V., Calvet, M., Villaseñor, A., Benahmed, S., Pauchet, H., and Grimaud, F.

Subjects
SEISMIC networks, EARTHQUAKE hazard analysis, SEISMIC tomography, SEISMOLOGY, SEDIMENTARY basins
Abstract

Local seismic networks are usually designed so that earthquakes are located inside them (primary azimuthal gap <<180°) and close to the seismic stations (0-100 km). With these local or near-regional networks (0°-5°), many seismological observatories still routinely locate earthquakes using 1-D velocity models. Moving towards 3-D location algorithms requires robust 3-D velocity models. This work takes advantage of seismic monitoring spanning more than 30 yr in the Pyrenean region. We investigate the influence of a well-designed 3-D model with station corrections including basins structure and the geometry of the Mohorovicic discontinuity on earthquake locations. In the most favourable cases (GAP < 180° and distance to the first station lower than 15 km), results using 1-D velocity models are very similar to 3-D results. The horizontal accuracy in the 1-D case can be higher than in the 3-D case if lateral variations in the structure are not properly resolved. Depth is systematically better resolved in the 3-D model even on the boundaries of the seismic network (GAP > 180° and distance to the first station higher than 15 km). Errors on velocity models and accuracy of absolute earthquake locations are assessed based on a reference data set made of active seismic, quarry blasts and passive temporary experiments. Solutions and uncertainties are estimated using the probabilistic approach of the NonLinLoc (NLLoc) software based on Equal Differential Time. Some updates have been added to NLLoc to better focus on the final solution (outlier exclusion, multiscale grid search, S-phases weighting). Errors in the probabilistic approach are defined to take into account errors on velocity models and on arrival times. The seismicity in the final 3-D catalogue is located with a horizontal uncertainty of about 2.0 ± 1.9 km and a vertical uncertainty of about 3.0 ± 2.0 km. [ABSTRACT FROM AUTHOR]

Published
2018
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8. Seismicity patterns in southwestern France

Author

Sylvander, Matthieu, Rigo, Alexis, Sénéchal, Guy, Battaglia, Jean, Benahmed, Sébastien, Calvet, Marie, Chevrot, Sébastien, Douchain, Jean-Michel, Grimaud, Frank, Letort, Jean, and Pauchet, Hélène

Subjects
Southwestern France, Pyrenees, Seismicity, Catalog, Cluster, Time behavior, Geophysics. Cosmic physics, QC801-809, Chemistry, QD1-999, Geology, QE1-996.5
Abstract

Seismic monitoring of southwestern France began in the 1960s, and homogeneous coverage by observation networks has been in place since the 1990s. The accumulation of data now allows a refined understanding of regional seismicity, not only on its spatial aspects, but also on the regularity of the earthquake distribution over time. This paper is both a review of the work carried out on the subject, and a progress report on the current knowledge of the regional seismicity in its seismotectonic context. With the support of maps, the available catalogs are exploited at different nested scales, from the region as a whole to the numerous clusters that characterize the seismicity of southwestern France, and more specifically that of the Pyrenees. An exhaustive study of these Pyrenean clusters and their temporal behavior is proposed, allowing in particular a better description of the prominent seismicity stripe to the northwest of the range.

Published
2021
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9. A detailed analysis of the February 1996 aftershock sequence in the eastern Pyrenees, France.

Author

Pauchet, H&eecaute;lène, Rigo, Alexis, Rivera, Luis, and Souriau, Annie

Subjects
*SEISMIC tomography, *SEISMOMETRY
Abstract

Presents the seismic analysis after the February 1996 earthquake in the French Pyrenees. Interpretations of the seismometers around the epicenter; Characterization of the aftershocks recorded; Elaboration of the post-earthquake stress within the focal mechanism.

Published
1999
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11. The non-cylindrical crustal architecture of the Pyrenees.

Author

Chevrot S, Sylvander M, Diaz J, Martin R, Mouthereau F, Manatschal G, Masini E, Calassou S, Grimaud F, Pauchet H, and Ruiz M

Abstract

We exploit the data from five seismic transects deployed across the Pyrenees to characterize the deep architecture of this collisional orogen. We map the main seismic interfaces beneath each transect by depth migration of P-to-S converted phases. The migrated sections, combined with the results of recent tomographic studies and with maps of Bouguer and isostatic anomalies, provide a coherent crustal-scale picture of the belt. In the Western Pyrenees, beneath the North Pyrenean Zone, a continuous band of high density/velocity material is found at a very shallow level (~10 km) beneath the Mauleon basin and near Saint-Gaudens. In the Western Pyrenees, we also find evidence for northward continental subduction of Iberian crust, down to 50-70 km depth. In the Eastern Pyrenees, these main structural features are not observed. The boundary between these two domains is near longitude 1.3 °E, where geological field studies document a major change in the structure of the Cretaceous rift system, and possibly a shift of its polarity, suggesting that the deep orogenic architecture of the Pyrenees is largely controlled by structural inheritance.

Published
2018
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