Testing the 2020 European Seismic Hazard Model (ESHM20) against observations from Romania

Abstract

Evaluating the performance of probabilistic seismic hazard models against recorded data and their potential to forecast future earthquake ground shaking is an emerging research topic. In this study, we evaluate and test the results of the recently released 2020 European Seismic Hazard Model (ESHM20; Danciu et al., 2021a, 2024) against observations for several cities in Romania. The dataset consists of ground-shaking recordings and macroseismic observations that extend the observational time period to a few hundred years. The full distribution of the hazard curves, depicting the epistemic uncertainties in the hazard at the given location was considered, and the testing was performed for peak ground acceleration (PGA) values of 0.1 and 0.2 g. The results show consistency between ESHM20 and the ground motion observations for the cities located near the Vrancea intermediate-depth source (VRI) for both selected PGA levels. ESHM20's estimated values appear to be over the recorded VRI ground motions along the Carpathian Mountains and below those at the far-field locations outside the Carpathians yet inside the expected model variability. Some of these differences might be attributed to the uncertainties in data conversion, local site effects, or differences in the attenuation patterns of the ground motion models. Our analysis suggests that the observed exceedance rates for the selected PGA levels are consistent with ESHM20 estimates, but these results must be interpreted with caution given the limited time and spatial coverage of the observations.