A quantitative structural approach to the study of active fault zones in the Apennines (Peninsular Italy)

The structural approach to the study of active fault zones in the High Agri Valley (in Southern Italy) and in the axial zones of the Central Apennines emphasises the need to focus on the acquisition of quantitative data in situ for assessing the permeability structure and the fractal properties of faults in order to constrain possible models of earthquake sources. Examples are discussed which suggest that fault behaviour during a seismic cycle is controlled mainly by pore fluid pressure variations oscillating around a state of near-criticality, and that the evolution and finite geometry of a fault zone are the result of self-organized criticality processes. Consequently, the fractal dimension of an active fault zone (which is a measure of the geometric complexity, and hence of the size of a finite fault zone pattern) has been used as an indication of the degree of maturity of the main seismogenic structures in these sectors of the Apennines and also to correlate the fault pattern of different seismic zones with the magnitude of the most damaging earthquakes which struck Central Italy in historical times.