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

Réponse rapide au tremblement de terre Mw 4.9 du 11 novembre 2019 au Teil, dans la basse vallée du Rhône, en France

Cécile Cornou (1) , Jean-Paul Ampuero (2) , Coralie Aubert (1) , Laurence Audin (3) , Stéphane Baize (4) , Jérémy Billant (2) , Florent Brenguier (1) , Mathieu Causse (1) , Mohamed Chlieh (1) , Andy Combey (1) , Marcello de Michele (5) , Bertrand Delouis (2) , Anne Deschamps (2) , Matthieu Ferry (6) , Michael Foumelis , Bérénice Froment (4) , Céline Gélis (4) , Raphaël Grandin (7) , Jean-Robert Grasso (1) , Estelle Hannouz (1) , Sébastien Hok (4) , Axel Jung (1) , Romain Jolivet (8) , Mickaël Langlais (1) , Philippe Langlaude (9) , Christophe Larroque (2) , Philippe Hervé Leloup (8) , Kevin Manchuel (10) , Léo Marconato (8) , Christophe Maron (2) , Emmanuel Mathot (11) , Emeline Maufroy (1) , Diego Mercerat (9, 2) , Marianne Métois (8) , Emmanuelle Neyman , Ildut Pondaven (1) , Ludmila Provost (4) , Julie Régnier (9, 2) , J.F. Ritz (6) , Diane Rivet (2) , Antoine Schlupp (12) , Anthony Sladen (2) , Christophe Voisin (1) , Andrea Walpersdorf (1) , David Wolyniec (1) , Pascal Allemand (8) , Elise Beck (13) , Etienne Bertrand (9) , Véronique Bertrand (14) , Pierre Briole (15) , Didier Brunel (2) , Olivier Cavalié (2) , Jérôme Chèze (2) , Françoise Courboulex (2) , Isabelle Douste-Bacqué (1) , Rémi Dretzen (14) , Tiziano Giampietro (2) , Maxime Godano (2) , Philippe Grandjean (8) , Marc Grunberg (14) , Gauthier Guerin (2) , Stephane Guillot (1) , Elias El Haber (1) , Alain Hernandez (14) , Hervé Jomard (4) , Cécile Lasserre (1) , Chao Liang (2) , Itzhak Lior (2) , Xavier Martin (2) , Daniel Mata (2) , Marine Menager (16) , Antoine Mercier (2) , Aurélien Mordret (1) , Elif Oral (2) , Anne Paul (1) , Fabrice Peix (2) , Catherine Péquegnat (1) , Michel Pernoud (9) , Claudio Satriano (7) , Rihab Sassi (4) , Marc Schaming (14) , Valérie Sellier , Christophe Sira (14) , Anne Socquet (1) , Christian Sue (17) , Aurélie Trilla (16) , Martin Vallée (7) , Martijn van den Ende (2) , Philippe Vernant (6) , Benjamin Vial (1) , Huihui Weng (2)

1 ISTerre - Institut des Sciences de la Terre
2 GEOAZUR 7329 - Géoazur
3 IRD - Institut de Recherche pour le Développement
4 IRSN - Institut de Radioprotection et de Sûreté Nucléaire
5 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
6 Géosciences Montpellier
7 IPGP (UMR_7154) - Institut de Physique du Globe de Paris
8 LGL-TPE - Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon]
9 Cerema - Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement
10 EDF - EDF
11 Terradue (ITALY)
12 IPGS - Institut de physique du globe de Strasbourg
13 PACTE - Pacte, Laboratoire de sciences sociales
14 EOST - Ecole et Observatoire des Sciences de la Terre
15 LGENS - Laboratoire de géologie de l'ENS
16 CEA - Commissariat à l'énergie atomique et aux énergies alternatives
17 LCE - Laboratoire Chrono-environnement (UMR 6249)

On November 11, 2019, a Mw 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 Rouviere 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.

Keywords: post-seismic; seismic sequence; Rhône valley; Le Teil Earthquake; RESIF

Domains: Sciences of the Universe [physics]; Earth Sciences; Tectonics

Cécile Cornou, Jean-Paul Ampuero, Coralie Aubert, Laurence Audin, Stéphane Baize, et al.. Rapid response to the Mw 4.9 earthquake of November 11, 2019 in Le Teil, Lower Rhône Valley, France. Comptes Rendus. Géoscience, 2021, 353 (S1), pp.1-23. ⟨10.5802/crgeos.30⟩. ⟨hal-03089600v2⟩