Rapid response to the M <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow/> <mml:mi mathvariant="normal">w</mml:mi> </mml:msub> </mml:math> 4.9 earthquake of November 11, 2019 in Le Teil, Lower Rhône Valley, France
Cécile Cornou, Jean‐Paul Ampuero, Coralie Aubert, Laurence Audin, Stéphane Baize, Jérémy Billant, Florent Brenguier, Mathieu Causse, M. Chlieh, Andy Combey, Marcello de Michele, Bertrand Delouis, A. Deschamps, Matthieu Ferry, Michalis Foumelis, Bérénice Froment, Céline Gélis, Raphaël Grandin, Jean‐Robert Grasso, Estelle Hannouz, Sébastien Hok, Axel Jung, Romain Jolivet, Mickaël Langlais, Philippe Langlaude, Christophe Larroque, Philippe Hervé Leloup, Kévin Manchuel, Léo Marconato, Christophe Maron, Emmanuel Mathot, Emeline Maufroy, Diego Mercerat, Marianne Métois, Emmanuelle Nayman, Ildut Pondaven, Ludmila Provost, Julie Régnier, Jean‐François Ritz, Diane Rivet, Antoine Schlupp, Anthony Sladen, Christophe Voisin, Andréa Walpersdorf, David Wolynieck, Pascal Allemand, Elise Beck, Étienne Bertrand, Véronique Bertrand, Pierre Briole, Didier Brunel, Olivier Cavalié, Jérôme Chèze, Françoise Courboulex, Isabelle Douste‐Bacqué, Rémi Dretzen, Tiziano Giampietro, Maxime Godano, Philippe Grandjean, Marc Grunberg, Gauthier Guérin, Stéphane Guillot, E. El Haber, Alain Hernandez, Hervé Jomard, Cécile Lasserre, Chao Liang, Itzhak Lior, Xavier Martin, Daniel Sánchez Mata, Marine Ménager, Antoine Mercier, Aurélien Mordret, Elif Oral, Anne Paul, Fabrice Peix, Cathérine Péquegnat, Michel Pernoud, Claudio Satriano, Rihab Sassi, Marc Schaming, Valérie Sellier, Christophe Sira, Anne Socquet, Christian Sue, Aurélie Guilhem Trilla, Martin Vallée, Martijn van den Ende, Philippe Vernant, Benjamin Vial, Huihui Weng
Abstract
On November 11, 2019, a M <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mrow/> <mml:mi mathvariant="normal">w</mml:mi> </mml:msub> </mml:math> 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.