Geological analysis and seismic hazard in the Central Apennines

This study puts forward a segmentation model applied to active faults with the aim of assessing seismic hazard in the Central Apennines. The model, whose reliability had been ascertained during the 1997 Umbria-Marche earthquake sequence, also implies a review of the key terms used in the analysis of active faults and points out the need for a specific procedure in geological analysis for seismic hazard evaluation. Earthquake events which occurred in the Central Apennines in the past decades show that several surface faults can be activated throughout a single seismic event. As a result, the segmentation model proposed herein is based on the fact that surface faults are, on the whole, the superficial manifestation of a single deep seismogenic structure. Therefore, this model is based on the possibility to recognize similar geological, structural, historical, geometrical and rheological features at the surface, in order to infer the main properties of the fault zone at depth. Eventually, on the grounds of the specific features of the fault array, one may assess the geometry, kinematics, slip-rate and size of the deep seismogenic structure, i.e., all the required parameters to evaluate the seismic potential of the area.