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1. New perspectives in studying active faults in metropolitan France: the 'Active faults France' (FACT/ATS) research axis from the Resif-Epos consortium

Author

Ritz, Jean-François, Baize, Stéphane, Audin, Laurence, Authémayou, Christine, Graveleau, Fabien, Kaub, Caroline, Lacan, Pierre, Leclerc, Frédérique, Larroque, Christophe, Manchuel, Kevin, Mugnier, Jean-Louis, Ortuño, Maria, Rizza, Magali, Vassallo, Riccardo, Antoine, Pierre, Arroucau, Pierre, Billant, Jérémy, Bollinger, Laurent, Ferry, Matthieu, Fillon, Charlotte, Geoffroy, Laurent, Jomard, Hervé, Le Roy, Pascal, Locht, Jean-Luc, Migeon, Sébastien, Perrin, Clément, Perrot, Julie, Ratzov, Gueorgui, Reicherter, Klaus, Soubigou, Olivier, Vergniault, Christophe, Viaplana-Muzas, Marc, and Van der Woerd, Jérôme

Subjects
FACT research axis (ATS-RESIF), Mainland France, Active fault, Paleoseismogy, Earthquake geology, Stable continental region, Plate interior, Geophysics. Cosmic physics, QC801-809, Chemistry, QD1-999, Geology, QE1-996.5
Abstract

Mainland France is part of a plate interior with a strong structural heritage, undergoing a low rate of deformation, where destructive earthquakes can nevertheless occur. In this paper, we emphasize that the knowledge of active faults is still largely fragmentary, and that significant efforts are needed to generate robust data, in particular on the numerous faults, that still lack any study. This is the aim of the “Failles ACTives France” (FACT) axis launched in the framework of the Transverse Seismicity Action (ATS) of the Resif-Epos consortium. We present some recent investigations carried out along suspected active faults in mountainous areas, their forelands and remote lowlands, which implement new approaches and new tools, and allow characterizing their Quaternary activity.

Published
2022
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2. Rapid response to the M$_{\protect \rm w}$ 4.9 earthquake of November 11, 2019 in Le Teil, Lower Rhône Valley, France

Author

Cornou, Cécile, Ampuero, Jean-Paul, Aubert, Coralie, Audin, Laurence, Baize, Stéphane, Billant, Jérémy, Brenguier, Florent, Causse, Mathieu, Chlieh, Mohamed, Combey, Andy, de Michele, Marcello, Delouis, Bertrand, Deschamps, Anne, Ferry, Matthieu, Foumelis, Michalis, Froment, Bérénice, Gélis, Céline, Grandin, Raphaël, Grasso, Jean-Robert, Hannouz, Estelle, Hok, Sébastien, Jung, Axel, Jolivet, Romain, Langlais, Mickaël, Langlaude, Philippe, Larroque, Christophe, Leloup, Philippe Hervé, Manchuel, Kevin, Marconato, Léo, Maron, Christophe, Mathot, Emmanuel, Maufroy, Emeline, Mercerat, Diego, Metois, Marianne, Nayman, Emmanuelle, Pondaven, Ildut, Provost, Ludmila, Régnier, Julie, Ritz, Jean-François, Rivet, Diane, Schlupp, Antoine, Sladen, Anthony, Voisin, Christophe, Walpersdorf, Andrea, Wolynieck, David, Allemand, Pascal, Beck, Elise, Bertrand, Etienne, Bertrand, Véronique, Briole, Pierre, Brunel, Didier, Cavalié, Olivier, Chèze, Jérôme, Courboulex, Françoise, Douste-Bacque, Isabelle, Dretzen, Rémi, Giampietro, Tiziano, Godano, Maxime, Grandjean, Philippe, Grunberg, Marc, Guerin, Gauthier, Guillot, Stéphane, Haber, Elias El, Hernandez, Alain, Jomard, Hervé, Lasserre, Cécile, Liang, Chao, Lior, Itzhak, Martin, Xavier, Mata, Daniel, Menager, Marine, Mercier, Antoine, Mordret, Aurélien, Oral, Elif, Paul, Anne, Peix, Fabrice, Pequegnat, Catherine, Pernoud, Michel, Satriano, Claudio, Sassi, Rihab, Schaming, Marc, Sellier, Valérie, Sira, Christophe, Socquet, Anne, Sue, Christian, Trilla, Aurélie, Vallée, Martin, van den Ende, Martijn, Vernant, Philippe, Vial, Benjamin, and Weng, Huihui

Subjects
Le Teil earthquake, Rhône valley, Seismic sequence, Post-seismic, Surface rupture, InSAR interferometry, Geophysics. Cosmic physics, QC801-809, Chemistry, QD1-999, Geology, QE1-996.5
Abstract

On November 11, 2019, a M$_{\mathrm{w}}$ 4.9 earthquake hit the region close to Montelimar (lower Rhône Valley, France), on the eastern margin of the Massif Central close to the external part of the Alps. Occuring in a moderate seismicity area, this earthquake is remarkable for its very shallow focal depth (between 1 and 3 km), its magnitude, and the moderate to large damages it produced in several villages. InSAR interferograms indicated a shallow rupture about 4 km long reaching the surface and the reactivation of the ancient NE–SW La Rouvière normal fault in reverse faulting in agreement with the present-day E–W compressional tectonics. The peculiarity of this earthquake together with a poor coverage of the epicentral region by permanent seismological and geodetic stations triggered the mobilisation of the French post-seismic unit and the broad French scientific community from various institutions, with the deployment of geophysical instruments (seismological and geodesic stations), geological field surveys, and field evaluation of the intensity of the earthquake. Within 7 days after the mainshock, 47 seismological stations were deployed in the epicentral area to improve the Le Teil aftershocks locations relative to the French permanent seismological network (RESIF), monitor the temporal and spatial evolution of microearthquakes close to the fault plane and temporal evolution of the seismic response of 3 damaged historical buildings, and to study suspected site effects and their influence in the distribution of seismic damage. This seismological dataset, completed by data owned by different institutions, was integrated in a homogeneous archive and distributed through FDSN web services by the RESIF data center. This dataset, together with observations of surface rupture evidences, geologic, geodetic and satellite data, will help to unravel the causes and rupture mechanism of this earthquake, and contribute to account in seismic hazard assessment for earthquakes along the major regional Cévenne fault system in a context of present-day compressional tectonics.

Published
2021
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6. Cosmogenic nuclide-derived downcutting rates of canyons within large limestone plateaus of southern Massif Central (France) reveal a different regional speleogenesis of karst networks.

Author

Malcles, Oswald, Vernant, Philippe, Fink, David, Cazes, Gaël, Ritz, Jean-François, Fujioka, Toshiyuki, and Chéry, Jean

Subjects
KARST, RIVER channels, FAULT zones, REGIONAL development, CANYONS
Abstract

We present 35 new burial ages (27 sites) based on 26 Al / 10 Be ratios of terrestrial cosmogenic radionuclides measured in clasts and sediments deep within 12 caves in the southern Massif Central, France. Our results, together with previously published burial ages, verify that cave morphogenesis has been continuously active in this region for at least the past ∼ 6 Myr. Combining sample burial ages with their associated cave elevation above the modern stream bed gives a mean regional incision rate of 88 ± 5 m Ma -1 for the Grands Causses area. South of the Cevennes Fault Zone bordering the Grands Causses, the incision rate is 43 ± 5 m Ma -1 , suggesting that this difference might be accommodated by the fault zone. Sediment burial ages from caves which are not located on river valley flanks or cliff walls are surprisingly too young compared to their expected ages when calculated using this regional average river incision rate. This suggests that the classical epigenic speleogenesis model that presumes a direct correlation between cave level development and regional base level lowering does not apply for the study area. Therefore, we propose that regional speleogenesis is mainly controlled by the removal of ghost rocks by headward erosion from river canyons to central parts of the plateaus, emptying incipient primokarst passages to create cave systems. Our results suggest a continuum process from hypogene primokarst composed of passages filled with ghost rock to one of epigene karst dynamics emptying these passages and creating cave networks. We propose that these processes are the major mechanism in the southern Massif Central that initiates speleogenesis and controls the geometry of the networks. In this region, tiered karst cannot be associated with the pace of incision of the major rivers but must be explained by former ghost rock (or hypogene) processes. [ABSTRACT FROM AUTHOR]

Published
2024
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7. Quelle place pour l’imagerie sismique dans la caractérisation des failles en domaine intraplaque ?

Author

Manchuel Kevin, Pouliquen Sylvain, Vergniault Christophe, Arroucau Pierre, Le Roux Mallouf Romain, and Ritz Jean-François

Subjects
Environmental sciences, GE1-350
Abstract

Localisés à distance des grandes limites de plaques lithosphériques, les domaines intraplaques présentent de faibles vitesses de déformation géologique, se traduisant par des niveaux de sismicité faibles à modérés, avec des temps de retour longs entre deux séismes significatifs. Dans ces régions, les processus de surface sont plus rapides que les processus tectoniques et tendent à effacer les éventuelles traces de rupture laissées en surface par des séismes majeurs du passé. L’estimation de l’activité des failles dans de tels contextes nécessite la mise en œuvre d’une approche pluridisciplinaire combinant géophysique, géologie et paléosismologie. Nous présentons ici l’approche développée par EDF, dans le cadre de ses études d’aléa sismique, pour améliorer la connaissance des failles en France métropolitaine, en se focalisant sur l’utilisation de la sismique réflexion (imagerie) à différentes échelles. Les lignes sismiques de Haute Résolution (HR ; i.e. sismique profonde de type pétrolière) permettent d’estimer la localisation et la géométrie des failles en profondeur, ainsi que leur histoire cinématique. La sismique ultra haute résolution en ondes S (UHRS) donne quant à elle une information sur la localisation des failles en très proche surface et permet de localiser d’éventuelles tranchées paléosismologiques visant à analyser l’activité des failles.

Published
2022
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12. Cosmogenic nuclide-derived downcutting rates of canyons within large limestone plateaus of southern Massif Central (France) reveal a different regional speleogenesis of karst networks

Author

Malcles, Oswald, Vernant, Philippe, Fink, David, Cazes, Gaël, Ritz, Jean-François, Fujioka, Toshiyuki, and Chery, Jean

Abstract

We present 27 new burial ages based on 26Al / 10Be ratios of terrestrial cosmogenic radionuclides measured in clasts and sediments deep within 12 caves in the southern Massif Central, France. Our results together with previously published burial ages, verifies that cave morphogenesis has been continuously active in this region for at least the past ~6 Myrs. Combining sample burial ages with their associated cave elevation above modern stream bed gives a mean regional incision rate of 88 ± 5 m/Ma for the Grands Causses area. South of the Cevennes Fault zone bordering the Grands Causses, the incision rate is 43 ± 5 m/Ma, suggesting that this difference might be accommodated by the fault zone. Sediment burial ages from caves which are not located on river valley flanks or cliff walls are surprisingly too young relatively to the expected age calculated using this regional average river incision rate. This suggests that the classical epigenic speleogenesis model that presumes a direct correlation between cave level development and regional base level lowering does not apply for the study area. Therefore, we propose that regional speleogenesis is mainly controlled by removal of ghost-rocks by regressive erosion from river canyons to central parts of the plateaus, emptying incipient primokarst passages to create cave systems. Our results suggest a continuum process from hypogene primokarst composed of ghost-rocks filled passages to epigene karst dynamic emptying these passages and creating cave networks. We propose this is a major process in the southern Massif Central that initiates the speleogenesis and control the geometry of the networks. In this region tiered karst cannot be associated with major incising rivers but must be explained by former ghost-rocks (or hypogene) processes.

Published
2023

15. Paleoseismological investigations of the La Rouvière fault, unexpected source of the 11-11-2019, Mw 4.9 Le Teil surface rupturing earthquake (Cévennes fault system, France)

Author

Ritz, Jean-François

Subjects
Paleoseismology, Le Teil earthquake, 2022 PATA Days field trip, La Rouvière fault
Abstract

This document synthesizes illustrations of the 2019 Le Teil earthquake surface effects and of the further paleoseismological investigations. The reported outcrops were described to the attendance of the 2022 INQUA PATA Days that were held in Aix-En-Provence (26 and 30 september, 2022).&nbsp

Published
2022
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18. Rapid response to the M w4.9 earthquake of November 11, 2019 in Le Teil, Lower Rhône Valley, France

Author

Cornou, Cécile, primary, Ampuero, Jean-Paul, additional, Aubert, Coralie, additional, Audin, Laurence, additional, Baize, Stéphane, additional, Billant, Jérémy, additional, Brenguier, Florent, additional, Causse, Mathieu, additional, Chlieh, Mohamed, additional, Combey, Andy, additional, de Michele, Marcello, additional, Delouis, Bertrand, additional, Deschamps, Anne, additional, Ferry, Matthieu, additional, Foumelis, Michalis, additional, Froment, Bérénice, additional, Gélis, Céline, additional, Grandin, Raphaël, additional, Grasso, Jean-Robert, additional, Hannouz, Estelle, additional, Hok, Sébastien, additional, Jung, Axel, additional, Jolivet, Romain, additional, Langlais, Mickaël, additional, Langlaude, Philippe, additional, Larroque, Christophe, additional, Leloup, Philippe Hervé, additional, Manchuel, Kevin, additional, Marconato, Léo, additional, Maron, Christophe, additional, Mathot, Emmanuel, additional, Maufroy, Emeline, additional, Mercerat, Diego, additional, Metois, Marianne, additional, Nayman, Emmanuelle, additional, Pondaven, Ildut, additional, Provost, Ludmila, additional, Régnier, Julie, additional, Ritz, Jean-François, additional, Rivet, Diane, additional, Schlupp, Antoine, additional, Sladen, Anthony, additional, Voisin, Christophe, additional, Walpersdorf, Andrea, additional, Wolynieck, David, additional, Allemand, Pascal, additional, Beck, Elise, additional, Bertrand, Etienne, additional, Bertrand, Véronique, additional, Briole, Pierre, additional, Brunel, Didier, additional, Cavalié, Olivier, additional, Chèze, Jérôme, additional, Courboulex, Françoise, additional, Douste-Bacque, Isabelle, additional, Dretzen, Rémi, additional, Giampietro, Tiziano, additional, Godano, Maxime, additional, Grandjean, Philippe, additional, Grunberg, Marc, additional, Guerin, Gauthier, additional, Guillot, Stéphane, additional, Haber, Elias El, additional, Hernandez, Alain, additional, Jomard, Hervé, additional, Lasserre, Cécile, additional, Liang, Chao, additional, Lior, Itzhak, additional, Martin, Xavier, additional, Mata, Daniel, additional, Menager, Marine, additional, Mercier, Antoine, additional, Mordret, Aurélien, additional, Oral, Elif, additional, Paul, Anne, additional, Peix, Fabrice, additional, Pequegnat, Catherine, additional, Pernoud, Michel, additional, Satriano, Claudio, additional, Sassi, Rihab, additional, Schaming, Marc, additional, Sellier, Valérie, additional, Sira, Christophe, additional, Socquet, Anne, additional, Sue, Christian, additional, Trilla, Aurélie, additional, Vallée, Martin, additional, van den Ende, Martijn, additional, Vernant, Philippe, additional, Vial, Benjamin, additional, and Weng, Huihui, additional

Published
2022
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19. Using Cosmogenic 3 He Dating of Fluvial Terraces for Estimating the Present Uplift of the Massif Central within the Northeastern Termination of the Cévennes Fault System

Author

Cathelin, Nicolas, BAIZE, Stephane, Ritz, Jean-François, Blard, Pierre-Henri, Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS), Institut de Radioprotection et de Sûreté Nucléaire (IRSN), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Université de Lorraine (UL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Résif

Subjects
Sismologie, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], RESIF, France, Seismology
Abstract

International audience; In 2019, the rupture of the La Rouvière fault leads to the Mw 4.9 earthquake of Le Teil and awakens great interest among the scientific community. Located on the North-East termination of the Cévenol fault system (CFS), an intraplate domain with extremely low deformation rates, La Rouvière fault, just as most of the neighboring fault segments, was not considered as potentially active. This event logically called into question our knowledge of regional dynamics and the seismogenic potential of the CFS faults. In this work, we aim to estimate the incision rates, in the normal to the CFS Escoutay valley, using cosmogenic 3He dating. This dating method unravels exposure ages of surfaces and is applied on basaltic pebbles because of their mineralogy (Ol., Px.). Dating those terraces on both sides of the CFS allows constraining incision rates in the valley and potentially the changes in uplift rates on a regional scale. The long-term objective of this study is to understand the recent history of these faults and what processes are triggering such reactivation.

Published
2021

20. Paléosismologie de la faille de La Rouvière, source inattendue du séisme du Teil (Mw4.9) du 11-11-2019 (Faille des Cévennes, France)

Author

Ritz, Jean-François, Baize, Stéphane, Ferry, Matthieu, Hannouz, Estelle, Riesner, Magali, Bollinger, Laurent, Larroque, Christophe, Audin, Laurence, Manchuel, Kévin, Rizza, Magali, Jomard, Hervé, Sue, Christian, Arroucau, Pierre, Billant, Jérémy, Bureau d'évaluation des risques sismiques pour la sûreté des installations (IRSN/PSE-ENV/SCAN/BERSSIN), Service de caractérisation des sites et des aléas naturels (IRSN/PSE-ENV/SCAN), Institut de Radioprotection et de Sûreté Nucléaire (IRSN)-Institut de Radioprotection et de Sûreté Nucléaire (IRSN), 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]), Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), SGF, CNRS, Laboratoire de Géologie de Lyon ou l’étude de la Terre, des planètes et de l’environnement, and Sciencesconf.org, CCSD

Subjects
[SDU] Sciences of the Universe [physics], Paléosismologie, Faille de la Rouvière, [SDU]Sciences of the Universe [physics], France, Séisme du Teil, ComputingMilieux_MISCELLANEOUS, Réseau de failles des Cévennes
Abstract

International audience

Published
2021

21. Localisation du choc principal et des répliques du séisme du Teil (2019/11/11, Mw 4,9) dans le contexte géologique de la bordure du bassin du Sud-Est (France)

Author

Larroque, Christophe, Godano, Maxime, Delouis, Bertrand, Courboulex, Françoise, Baize, Stephane, Ritz, Jean-François, Oral, Elif, Ampuero, Jean Paul, 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]), and Larroque, Christophe

Subjects
réplique, faille de la Rouvière, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, géologie, séisme du Teil, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2021

22. Location of the mainshock and aftershocksof the Le Teil earthquake (2019/11/11, Mw 4.9) in the geological context of the Southeast Basin edge (France)

Author

Larroque, Christophe, Godano, Maxime, Delouis, Bertrand, Courboulex, Françoise, Baize, Stephane, Ritz, Jean-François, Oral, Elif, Ampuero, Jean Paul, Billant, Jeremy, Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), and Larroque, Christophe

Subjects
[SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2021

24. Le séisme du Teil - Saint-Thomé : aspect sismologiques et géologiques

Author

BAIZE, Stephane, Ritz, Jean-François, Larroque, Christophe, Audin, Laurence, FERRY, Matthieu, Larroque, Christophe, Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, and 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])

Subjects
[SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics]
Abstract

National audience; Le 11 novembre 2019, le sud de la France a connu un séisme de magnitude de moment Mw 4.9 qui a fait trembler l’Ardèche et la Drôme, et qui a été ressenti jusqu’à Marseille et Montpellier. L’épicentre est situé près de la ville du Teil dans la vallée du Rhône, dans une zone densémentpeuplée avec de nombreuses installations industrielles dont deux centrales nucléaires situées à moins de 25 km. Le séisme a causé des dégâts importants dans les villages du Teil, de Saint Thomé et de Viviers, fissurant des murs épais et provoquant la chute de tuiles, de cheminées et de cadres de fenêtres. Localement, des habitations ont même subi un effondrement partiel, notamment dans le hameau de la Rouvière proche de la faille-source du séisme. Rapidement après le séisme, les calculs précis de localisation ont montré que le foyer du séisme était très superficiel, avec une profondeur comprise entre 1 et 3 km, suggérant que la rupture sismique avait pu atteindrela surface du sol. L’hypocentre superficiel et la présence d’une importante carrière de calcaire à ciel ouvert près de l’épicentre ont immédiatement soulevé la question de l’origine anthropique du séisme. L’INSU-CNRS a alors mandaté un groupe d’experts pour traiterla question. Leur rapport, publié en ligne 40 jours après l’événement (Delouis et al., 2019), a conclu que le déficit de masse dû à l’extraction de matériaux de la carrière pourrait avoir contribué au déclenchement du séisme. Cependant, les experts soulignèrent également que l’origine et la puissance du séisme étaient dues à l’accumulation naturelle de contraintes tectoniques au fil du temps.

Published
2021

25. New perspectives in studying active faults in metropolitan France: the “Active faults France” (FACT/ATS) research axis from the Resif-Epos consortium

Author

Ritz, Jean-françois, Baize, Stéphane, Audin, Laurence, Authémayou, Christine, Graveleau, Fabien, Kaub, Caroline, Lacan, Pierre, Leclerc, Frédérique, Larroque, Christophe, Manchuel, Kevin, Mugnier, Jean-louis, Ortuño, Maria, Rizza, Magali, Vassallo, Riccardo, Antoine, Pierre, Arroucau, Pierre, Billant, Jérémy, Bollinger, Laurent, Ferry, Matthieu, Fillon, Charlotte, Geoffroy, Laurent, Jomard, Hervé, Le Roy, Pascal, Locht, Jean-luc, Migeon, Sebastien, Perrin, Clément, Perrot, Julie, Ratzov, Gueorgui, Reicherter, Klaus, Soubigou, Olivier, Vergniault, Christophe, Viaplana-muzas, Marc, Van Der Woerd, Jérôme, Ritz, Jean-françois, Baize, Stéphane, Audin, Laurence, Authémayou, Christine, Graveleau, Fabien, Kaub, Caroline, Lacan, Pierre, Leclerc, Frédérique, Larroque, Christophe, Manchuel, Kevin, Mugnier, Jean-louis, Ortuño, Maria, Rizza, Magali, Vassallo, Riccardo, Antoine, Pierre, Arroucau, Pierre, Billant, Jérémy, Bollinger, Laurent, Ferry, Matthieu, Fillon, Charlotte, Geoffroy, Laurent, Jomard, Hervé, Le Roy, Pascal, Locht, Jean-luc, Migeon, Sebastien, Perrin, Clément, Perrot, Julie, Ratzov, Gueorgui, Reicherter, Klaus, Soubigou, Olivier, Vergniault, Christophe, Viaplana-muzas, Marc, and Van Der Woerd, Jérôme

Abstract

Mainland France is part of a plate interior with a strong structural heritage, undergoing a low rate of deformation, where destructive earthquakes can nevertheless occur. In this paper, we emphasize that the knowledge of active faults is still largely fragmentary, and that significant efforts are needed to generate robust data, in particular on the numerous faults, that still lack any study. This is the aim of the “Failles ACTives France” (FACT) axis launched in the framework of the Transverse Seismicity Action (ATS) of the Resif-Epos consortium. We present some recent investigations carried out along suspected active faults in mountainous areas, their forelands and remote lowlands, which implement new approaches and new tools, and allow characterizing their Quaternary activity.

Published
2021
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26. Âges d’enfouissement, fantômes de roches et structuration karstique, cas de la vallée de la Vis (Sud de la France)

Author

Malcles, Oswald, VERNANT, Philippe, Chery, Jean, Ritz, Jean-François, Cazes, Gaël, Fink, David, Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS), School of Earth and Environmental Sciences [University of Wollongong], University of Wollongong [Australia], and Australian Nuclear Science and Technology Organisation [Australie] (ANSTO)

Subjects
Processus, [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, Terrestrial Cosmogenic Nuclide, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, fantômisation, cave system Relief, Environnement, ghost rock, karstification, [SDU]Sciences of the Universe [physics], réseaux karstiques Larzac, âges d' enfouissement 26 Al/ 10 Be, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, Larzac
Abstract

International audience; New burial ages of cave deposits, based on the 26Al/10Be cosmogenic isotope ratio technique, from three caves in the Vis Valley, located in the south-east perimeter of the “Grands-Causses” in southern France are challenging the validity of classic karstic evolution models to explain the structure and evolution of the karstic network in the region. Generally speaking, the formation of horizontal galleries at different elevations above the canyon floor is commonly used as time-markers of former regional base level positions. The burial ages obtained for the Bergougnous cave (1.2 ± 0.3 Ma, +117 m above base level -a.b.l.-) and the Scorpions cave 1.2 ± 0.4 Ma, +105 m a.b.l.) are in agreement with the regional river-incision rate (83 ± 35 m.Ma-1) and conform to a classical per descensum evolution of the karst network. However, the emplacement of alluvium deposits within the Rocas cave at 0.94 ± 0.07 Ma is not consistent with a regular per descensum model. The Rocas cave is 317 m a.b.l. but its entrance is located on the plateau about 4 kilometres from the Vis canyon crest whereas, in contrast, the two caves listed above open directly onto the wall of the Vis canyon. To our knowledge, this is the first presentation of quantitative data which supports the observation that karstic horizontal levels are not always directly controlled by the regional base level position. We support our findings with absolute ages, which for the first time, demonstrates the primary importance of the ghost-rock process on the location of horizontal levels. Base level location is then a secondary parameter, mainly involved in a triggering event for ghost-rock erosion

Published
2020
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27. Geomorphology of the cumulative deformation since Oligocene age on the Mw 4.9 Le Teil earthquake fault (South of France,11/11/19)

Author

Hannouz, Estelle, Sue, Christian, Baize, Stephane, Ritz, Jean-François, Ferry, Matthieu, Audin, Laurence, Larroque, Christophe, Walpersdorf, A., Lemoine, Anne, Institut des Sciences de la Terre (ISTerre), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA), 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]), and Larroque, Christophe

Subjects
[SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2020

28. Séisme du Teil : où en est-on de l'analyse de cet événement inédit un an après ?

Author

Ritz, Jean-François, Cornou, Cécile, Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Institut des Sciences de la Terre (ISTerre), and Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel-Université Grenoble Alpes (UGA)

Subjects
Sismologie, Séisme de Le Teil, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], RESIF
Abstract

National audience; Il y a un an, le séisme du Teil du 11 novembre 2019, de magnitude Mw 4.9, faisait trembler l'Ardèche et endommageait fortement la région épicentrale avec une intensité EMS98 évaluée à VIII, provoquant de très gros dégâts estimés à plusieurs dizaines de millions d'euros. Correspondant au séisme le plus destructeur depuis le tremblement de terre d'Arette (Pyrénées) en 1967 (ML 5.3, MSK VII-VIII), la catastrophe avait été largement couverte par les médias qui avaient à l'époque, concentré leurs interventions autour de la question de l'influence ou non de l'activité anthropique sur le déclenchement du séisme.

Published
2020

29. Analyzing the paleoseismic history of the La Rouvière fault, unexpected source of the 11-11-2019, Mw4.9 Le Teil surface rupturing earthquake (Cévennes fault system, France) 

Author

Ritz, Jean-François, primary, Baize, Stéphane, additional, Ferry, Matthieu, additional, Hannouz, Estelle, additional, Riesner, Magali, additional, Bollinger, Laurent, additional, Larroque, Christophe, additional, Audin, Laurence, additional, Manchuel, Kevin, additional, Rizza, Magali, additional, Jomard, Hervé, additional, Sue, Christian, additional, Arroucau, Pierre, additional, and Billant, Jérémy, additional

Published
2021
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31. Rapid response to the Mw 4.9 earthquake of November 11, 2019 in Le Teil, Lower Rhône Valley, France

Author

Cornou, Cécile, primary, Ampuero, Jean-Paul, additional, aubert, Coralie, additional, Audin, Laurence, additional, Baize, Stéphane, additional, Billant, Jérémy, additional, Brenguier, Florent, additional, Causse, Mathieu, additional, Chlieh, Mohamed, additional, Combey, Andy, additional, de Michele, Marcello, additional, Delouis, Bertrand, additional, Deschamps, Anne, additional, Ferry, Matthieu, additional, Foumelis, Michael, additional, Froment, Bérénice, additional, Gélis, Céline, additional, Grandin, Raphaël, additional, grasso, jean-robert, additional, Hannouz, Estelle, additional, Hok, Sébastien, additional, Jung, Axel, additional, Jolivet, Romain, additional, Langlais, Mickaël, additional, Langlaude, Philippe, additional, Larroque, Christophe, additional, Leloup, Philippe Hervé, additional, Manchuel, Kevin, additional, Marconato, Léo, additional, Maron, Christophe, additional, Mathot, Emmanuel, additional, Maufroy, Emeline, additional, Mercerat, Diego, additional, Métois, Marianne, additional, Neyman, Emmanuelle, additional, Pondaven, Ildut, additional, Provost, Ludmila, additional, Régnier, Julie, additional, Ritz, Jean-François, additional, Rivet, Diane, additional, Schlupp, Antoine, additional, Sladen, Anthony, additional, Voisin, Christophe, additional, Walpersdorf, Andrea, additional, Wolynieck, David, additional, Allemand, Pascal, additional, Beck, Elise, additional, Bertrand, Etienne, additional, Bertrand, Véronique, additional, Briole, Pierre, additional, Brunel, Didier, additional, Cavalié, Olivier, additional, Chèze, Jérôme, additional, Courboulex, Françoise, additional, Douste-Bacqué, Isabelle, additional, Dretzen, Rémi, additional, Giampietro, Tiziano, additional, Godano, Maxime, additional, Grandjean, Philippe, additional, Grunberg, Marc, additional, Guérin, Gauthier, additional, Guillot, Stéphane, additional, Haber, Elias el, additional, Hernandez, Alain, additional, Jomard, Hervé, additional, Lasserre, Cécile, additional, Liang, Chao, additional, Lior, Itzhak, additional, Martin, Xavier, additional, Mata, Daniel, additional, Ménager, Marine, additional, Mercier, Antoine, additional, Mordret, Aurélien, additional, Oral, Elif, additional, Paul, Anne, additional, Peix, Fabrice, additional, Péquégnat, Catherine, additional, Pernoud, Michel, additional, Satriano, Claudio, additional, Sassi, Rihab, additional, Schaming, Marc, additional, Sellier, Valérie, additional, Sira, Christophe, additional, Socquet, Anne, additional, Sue, Christian, additional, Trilla, Aurélie, additional, Vallée, Martin, additional, van den Ende, Martijn, additional, Vernant, Philippe, additional, Vial, Benjamin, additional, and Weng, Huihui, additional

Published
2020
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40. Geometry and tectonic history of the Northeastern Cévennes Fault System (Southeast Basin, France) : new insights from deep seismic reflection profiles

Author

Thomasset, Camille, Ritz, Jean-François, Pouliquen, Sylvain, Manchuel, Kevin, Le-Roux-Mallouf, Romain, Thomasset, Camille, Ritz, Jean-François, Pouliquen, Sylvain, Manchuel, Kevin, and Le-Roux-Mallouf, Romain

Abstract

Following the Mw4.9 Le Teil surface rupture earthquake that occurred on the north-eastern Cévennes fault system (NCFS) in France, several investigations were carried out to understand the origin of the earthquake rupture. A few studies performed local modeling of the NCFS structures in three dimensions integrating the rheology of the sedimentary layers within the hypocenter zone. However, the geometry of the NCFS at the scale of the Southeast French Basin is poorly constrained and it remains difficult to locate its trace beneath the Quaternary sediments of the Rhône river valley. To address this issue, Électricité de France (EDF) carried out a deep reflection seismic survey along the NCFS. This new set of seismic profiles was interpreted using a geological data base including surface data, well data, and previous seismic data that were reprocessed. The resulting 3D structural model allows us to reconstruct a polyphase geological history during the past 320 Ma, which we divide into three major tectonic phases. We show that all structures in the basin in the study area were initiated as normal faults during the Lower Jurassic and the Lower Cretaceous. During the Upper Cretaceous, these structures were reactivated, acting as a major transfer fault zone during the Pyrenean shortening phase, then as normal faults during the Oligocene extension. The morphology and faults at the top-Carboniferous basin initiated during the Lower Jurassic strongly shaped the final structure of the NCFS during the subsequent tectonic phases. Our new results allow updating the historical geology of the Vivaro-Cévenol region and our knowledge about the structures that have affected the Southeast Basin since the Mesozoic. In the context of the Le Teil earthquake, our new structural model provides important constraints for continuing paleoseismological works that will better assess the seismic hazard in this region.

Published
2024
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45. Geologic Inheritance and Earthquake Rupture Processes: The 1905 M ≥ 8 Tsetserleg‐Bulnay Strike‐Slip Earthquake Sequence, Mongolia

Author

Choi, Jin‐Hyuck, primary, Klinger, Yann, additional, Ferry, Matthieu, additional, Ritz, Jean‐François, additional, Kurtz, Robin, additional, Rizza, Magali, additional, Bollinger, Laurent, additional, Davaasambuu, Battogtokh, additional, Tsend‐Ayush, Nyambayar, additional, and Demberel, Sodnomsambuu, additional

Published
2018
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48. The Dinaric fault system: Large-scale structure, rates of slip, and Plio-Pleistocene evolution of the transpressive northeastern boundary of the Adria microplate

Author

Moulin, Adrien, Benedetti, Lucilla, Rizza, Magali, Rupnik, Petra, Gosar, Andrej, Bourles, Didier, Keddadouche, Karim, Aumaître, Georges, Arnold, Maurice, Guillou, Valery, Ritz, Jean-François, Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Geological Survey of Slovenia, Ljubljana, Faculty of Natural Sciences and Engineering, Ljubljana, Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Geological Survey of Slovenia (GeoZS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)

Subjects
[SDE.MCG]Environmental Sciences/Global Changes
Abstract

International audience; Located at the northeastern corner of the Adria microplate, the Alps-Dinarides junction represents a key region for understanding how the Adria microplate interacts with stable Europe. However, little is known on how the present-day deformation imposed by the rotation of the Adria microplate is absorbed across the Dinarides. Using morphotectonic analysis based on satellite and aerial images, accurate topographical maps, and digital elevation models combined with field investigations, we mapped in detail the three main active faults of the Northern Dinarides. Geomorphic and geological cumulative displacements ranging from a few meters to several kilometers have been identified on those faults and dated for the most recent ones using 36 Cl exposure dating. Those results yielded a total right-lateral motion of 3.8 ± 0.7 mm/yr oriented N317. Comparing our results with the motion expected from Adria rotation models suggests that the Northern Dinarides absorbs most of the predicted Adria-Eurasia motion, thus representing the eastern boundary of the microplate. However, a significant E-W component is lacking, suggesting that part of the stress imposed by the microplate rotation is transferred farther to the east. Finally, bounds placed on the Plio-Pleistocene kinematics confirm that faulting onset occurred during the Early Pliocene and evidence a significant kinematic change at the Early/Middle Pleistocene boundary.

Published
2016
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49. Palaeoseismic evidence for a medieval earthquake, and preliminary 0 Cross Mark estimate of late Pleistocene slip-rate, on the Firouzkuh strike-slip fault in the Central Alborz region of Iran

Author

Nazari, H., Ritz, Jean-François, Walker, R. T., Salamati, Reza, Rizza, Magali, Patnaik, R., Hollingsworth, J., Alimohammadian, H., Jalali, A., Firouz, A. Kaveh, Shahidi, A., Geological Survey of Iran, Géosciences Montpellier, Université des Antilles et de la Guyane (UAG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Risques (Géosciences Montpellier), Université des Antilles et de la Guyane (UAG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles et de la Guyane (UAG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Department of Earth Sciences, University of Oxford, University of Oxford [Oxford], Centre for Petroleum and Applied Geology [Chandigarh], Panjab University [Chandigarh], Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, 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]), Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)

Subjects
[SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics, [SDE.MCG]Environmental Sciences/Global Changes, Medieval earthquake, Paleoseismology, Firouzkuh Fault, Slip-rate, Iran
Abstract

International audience; The ∼55 km-long Firouzkuh fault is located in the Central Alborz Mountains of Iran. It is a left-lateral fault, which dips to the south, and possesses a small dip-slip component of motion that we interpret to result from extension. The ratio of horizontal to vertical displacement across the fault, calculated from the cumulative displacement of landscape features, is 7.6. We provide constraints on the timing of the last earthquake on the Firouzkuh fault from two trenches (T1 and T2) across the fault zone, excavated in 2004, and located east of Firouzkuh city. The trenches expose faulted sedimentary deposits. Two optically-stimulated luminescence (OSL) ages from sediments in the lower part of trench T1 date from the late Pleistocene (15.9 ± 0.9 ka and 27.1 ± 1.7 ka). The younger of the two dated units in T1 is displaced vertically across the fault by 2.2–4.4 m, from which we estimate a strike-slip displacement of 18.2–33.4 m, and hence a average horizontal slip-rate of 1.1–2.2 mm/yr. The sediments exposed in T1 do not yield constraints on the most recent earthquake history. In trench T2, however, human skeletal remains of a middle aged male, which yield a radiocarbon age of 1159 ± 28 BP (corresponding to a mean calendar age of 791 AD), were found within a faulted alluvial layer at a depth of 60–70 cm from the surface. The existence of these medieval human places shows that a surface-rupturing earthquake occurred at some time after 1159 ± 28 BP. The amount of slip in each earthquake on the Firouzkuh fault is difficult to estimate, but assuming the entire ∼55 km fault length ruptures in each event, they will have had a maximum magnitude of 7.1. At our estimated late Quaternary slip-rate of ∼1.1–2.2 mm/yr magnitude 7.1 earthquakes, involving ∼1.2 m average displacement, would be expected to occur every ∼1100–540 years. As the last earthquake on the Firouzkuh fault may be up to ∼700 years in age we suggest that the Firouzkuh fault is a major hazard for earthquakes in the near future.

Published
2014
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