Ground effects and surface faulting in the September-October 1997 Umbria-Marche (Central Italy) seismic sequence

摘要: The September–October 1997 seismic sequence in the Umbria–Marche regions of Central Italy (main shocks on September 26, Mw 5.7 and 6.0, October 14, 5.6) left significant ground effects, which were mainly concentrated Colfiorito intermountain basin. These effects included surface faulting, cracks settlements, rock falls, slides, hydrological gas anomalies. distribution size has proved useful for (1) defining epicentral area location causative fault; (2) complementing intensity pattern from damage (this can be very poorly inhabited zones); (3) integrating or testing assessment many historical events, order to obtain a better evaluation magnitude data. Of special interest was observation ruptures generated along segments system normal faults already mapped as capable, with end-to-end lengths 12 km maximum displacements 8 cm. Many pieces evidence confirm that coseismic slip not secondary, gravity-induced, phenomenon, but had tectonic origin. Detailed descriptions faulting moderate earthquakes are common, being easily missed misinterpreted; however, this paper we emphasize due event used infer threshold Apennines, allowing calibrate palaeoearthquake fault offsets seen trench investigations.