First calibration of the physics-based ground motion model of the 2019 Mw4.9 Le Teil earthquake (France)

The seismic risk in France, a region of low to moderate seismicity, is of paramount importance given the large number of industrial and nuclear installations. However, the large uncertainties on the geology and the poor knowledge of active faults make the seismic hazard estimation a challenging task. Despite being a promising tool to explore the underlying uncertainties, numerical simulations must be duly calibrated by reproducing specific events.

In this work, we considered the 2019 Mw4.9 earthquake that occurred at Le Teil village in southern France. This event was recorded by 17 stations of 3-component accelerometers, within an area of 50 km around the epicenter (French Accelerometric Network). We used these records to calibrate the numerical simulation. The seismological P- and S-wave speed profiles used result from a 3D weighted average model for Metropolitan France. In addition, the topography was included in the spatial discretization. The uncertainties on dip, strike, and rake angles were explored in order to calibrate the far-field synthetic ground motion model by determining the eigenquakes that efficiently span a large diversity of sources.

A good agreement between synthetic and recorded time histories was found, despite the simplicity of the geological and source model.