Investigation of historical earthquake by seismic wave propagation simulation: Source parameters of the 1887 M6.3 Ligurian, north-western Italy, earthquake

Abstract : High performance numerical simulation of the seismic wave propagation from the earthquake source to the ground motion is a powerful approach to investigate the earthquake and its sequence. As the modern instrumental observational seismology has lasted only since a few decades, the numerical investigation is essential for studying the past historical earthquakes or assessing the future earthquakes for which there are no data. For French Metropolitan, the 1887 Ligurian earthquake is one of the most damaging earthquakes, whose position is estimated in the north-western Italy close to the border to France, off shore of the Mediterranean coast. We carry out numerical simulations of the ground motion, using a 3D Finite Difference Method (FDM), based on the supposed potential earthquake scenarios. Through testing earthquake scenarios and comparing to the spatial pattern of the damaging (intensity), we test different scenarios of this earthquake based on the seismotectonic insights, (1) a shallow normal faulting close to the coastline, (2) a shallow reverse faulting off shore and (3) a deep reverse faulting close to the coastline. Our simulation results improve our knowledge of past phenomena and contribute to the assessment of the regional seismic hazard.