Abstract:
Objectives The Mw 4.9 Le Teil earthquake that occurred on November 11, 2019 is the most destructive earthquake recorded in the Rhône River Valley of France.
Methods We first used Sentinel-1 data to calculate the coseismic displacement field of the Le Teil earthquake with the GAMMA software package. We then obtained fault geometric parameters and coseismic displacement fields based on Bayesian inversion and the steepest descent method (SDM). We last quantified the effects of quarry extraction activity on fault by using the digital elevation model (DEM) data acquired in 2000 and 2006—2011. We calculated the extraction volume and the Coulomb stress change on the fault plane based on the Boussinesq solution of three dimension homogeneous and elastic half-space.
Results The coseismic displacement field show that the largest displacements in the line of sight of the ascending and descending orbits are 14.9 cm and 8.6 cm, respectively. We find that the seismogenic fault has a southeast dip angle of 72°, a strike of 54° and an average rake of 108°; the earthquake rupture reached the surface, with a rupture area of about 3 413 m×1 358 m, and a depth of about 1.472 km. The slip is over 0.15 m and is concentrated at a depth of 0–0.75 km with a peak slip of 0.2 m. We calculated the geodetic magnitude to be Mw 4.79. The Coulomb stress change on the fault plane is 0.024 MPa in 6–11 years after 2000.
Conclusions The rock extraction of the Le Teil quarry had been active during 1833—2019, and the extraction is even more intense after 2007. The Coulomb stress change on the fault plane could reach up to 0.1 MPa, which is much larger than the local tectonic loading rate, suggesting that the Le Teil earthquake is strongly related to rock extraction activities.
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