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

On November 11, 2019, a M-w 4.9 earthquake hit the region close to Montelimar (lower Rhone 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 Cevenne fault system in a context of present-day compressional tectonics.

Automated summary

In November 11, 2019, a M-w 4.9 earthquake occurred near Montelimar, France, with a very shallow focal depth and causing moderate to large damages in several villages. The lack of monitoring stations prompted a swift response from the French scientific community to deploy instruments, conduct field surveys, and study the earthquake's intensity. This comprehensive dataset aims to unravel the earthquake's causes, rupture mechanism, and contribute to seismic hazard assessment in the region.