Reconstructed seismic and tsunami scenarios of the 1905 Calabria earthquake (SE Tyrrhenian sea) as a tool for geohazard assessment

Italy is one of the most seismically active regions in the central Mediterranean and one of the countries with thelongest record of historical earthquakes in the world. Over the last decades the scientific community hasrecognised the value of historical data when used to constrain modelling tools in hazard analyses. This is the caseof the destructive 1905 Calabria (South Italy) earthquake, followed by a tsunami and by many secondary effectson the environment observed both inland and offshore. Recently acquired geophysical data allowed to identifyan active normal fault, named Sant'Eufemia Fault, located nearshore in the Sant'Eufemia Gulf (SE Tyrrheniansea), considered the most probable seismogenic source of the 1905 earthquake and capable to trigger futureevents.In this paper we perform a scenario-based deterministic analysis for an earthquake resulting from the ruptureof the Sant'Eufemia fault (SEF) and a preliminary potential risk analysis. After defining source parameterscompatible with the 1905 earthquake (ca. 40 km fault length and ca. 2.3 m slip, Mw 6.9), KF-analysis andtsunami simulations are carried out and modelling results are compared against historical available data. Theobtained results allow one to border areas in central Calabria that are most exposed to geohazard deriving fromthe analyzed fault. Some of these areas happen to be zones with intense economic/touristic and urbandevelopment, which calls for the need to integrate the ongoing development plans with adequate programs ofrisk mitigation and prevention.