Ground motion simulations of historical earthquakes: the case study of the Fabriano (1741, Mw = 6.1) and Camerino (1799, Mw = 6.1) earthquakes in central Italy

The determination of ground motion is crucial to plan the appropriate emergency activities, especially in areas characterised by an intense seismic history like the Italian peninsula. Ground motion assessment is generally based on the seismological parameters reported in the instrumental and parametric seismic catalogues. Therefore, the computation of shaking scenarios of historical earthquakes is very challenging, due to the poorly constrained variables (i.e., magnitudes, epicentral location, seismogenic sources), derived from the macroseismic intensity. In this study, we propose a novel approach to investigate the location and parametrization of the seismogenic sources of historical earthquakes and derive shaking scenarios. To this aim, the ground motion of two historical events, the Fabriano (1741, Mw = 6.1, Imax IX MCS) and Camerino (1799, Mw = 6.1, Imax IX-X MCS) earthquakes is simulated. In order to include the site response, a Vs,30 map of the Umbria and Marche regions is created from near-surface data. Different causative faults solutions are tested, finally discussing the ideal seismogenic source based on the residual analysis between observed and simulated macroseismic intensities. The resultant shaking scenarios of the two events are obtained by integrating observed intensities and simulations.