Validation of regional physics-based ground motion scenarios: the case of the Mw 4.9 2019 Le Teil earthquake in France

Abstract In this paper, a comprehensive validation exercise of 3D physics-based numerical simulations (PBS) of seismic wave propagation is presented for a low-to-moderate seismicity area in the south east of France, within the Rhône River Valley, that hosts several operating nuclear installations. This area was hit on Nov 11, 2019, by an unusually damaging Mw 4.9 earthquake (Le Teil event). The numerical code SPEED (http://speed.mox.polimi.it/), developed at Politecnico di Milano, Italy, was used to validate the simulations against the available recordings. When comparing simulations with records, a good to excellent agreement was found up to 8–10 Hz, showing that, even without a very detailed 3D numerical model of the medium, the PBS may provide realistic broadband predictions of earthquake ground motion. This also demonstrates that PBS, if suitably calibrated and validated, may be either an alternative or a useful complement to empirical ground motion models. Referring to the seismic risk evaluation of strategic and critical structures, infrastructures and industrial plants, such as nuclear power plants, the failure of which during an earthquake may endanger safety of population and cause environmental disasters, the 3D PBS may throw light on region- and site-specific features of ground shaking, especially in near-source conditions, that are typically poorly constrained in empirical models.