Exceptional ground motion during the shallow Mw 4.9 2019 Le Teil earthquake, France

Mathieu Causse,Emeline Maufroy,Elias El Haber,Laurent Baillet,Cécile Cornou,Jean-Robert Grasso

doi:10.1038/s43247-020-00089-0

Abstract

An unusually damaging Mw 4.9 earthquake occurred on November 11, 2019 in the south east of France within the lower Rhône river valley, an industrial region that hosts several operating nuclear power plants. The hypocentre of this event occurred at an exceptionally shallow depth of about 1 km. Here we use far-field seismological observations to demonstrate that the rupture properties are consistent with those commonly observed for large deeper earthquakes. In the absence of strong motion sensors in the fault vicinity, we perform numerical predictions of the ground acceleration on a virtual array of near-fault stations. These predictions are in agreement with independent quantitative estimations of ground acceleration from in-situ observations of displaced objects. Both numerical and in-situ analyses converge toward estimates of an exceptional level of ground acceleration in the fault vicinity, that locally exceeded gravity, and explain the unexpectedly significant damage.

Highlights

An unusually damaging Mw 4.9 earthquake occurred on November 11, 2019 in the south east of France within the lower Rhône river valley, an industrial region that hosts several operating nuclear power plants
In the absence of near-fault strong motion recording for the Le Teil earthquake we conduct numerical predictions of the ground acceleration (Fig. 1b)
The 2019 Mw4.9 Le Teil earthquake occurred in a stable continental region at unusually shallow depth (~1 km)

Summary

Introduction

An unusually damaging Mw 4.9 earthquake occurred on November 11, 2019 in the south east of France within the lower Rhône river valley, an industrial region that hosts several operating nuclear power plants. In the absence of strong motion sensors in the fault vicinity, we perform numerical predictions of the ground acceleration on a virtual array of near-fault stations. These predictions are in agreement with independent quantitative estimations of ground acceleration from in-situ observations of displaced objects. On November 11, 2019, a Mw 4.9 earthquake occurred in the south east of France (referred to as the Le Teil event, Fig. 1a) close to the city of Montélimar within the lower Rhône river valley, a moderate seismicity area This industrial region hosts several operating nuclear power plants. Our study provides new insights on seismic hazard due to superficial seismicity in stable continental regions

Methods

Results

Conclusion