Studio dei movimenti gravitativi di S. Romano in Garfagnana (Valle di Serchio, Lucca)

Study of gravitational movements of the S. Romano in Garfagnana area (Serchio Valley, North-Western Tuscany), Italy

Abstract

1. Romano in Garfagnana is a village of Garfagnana, a high seismicity region of Northern Apennines. The village lies on a slope where sandstone outcrops, overlaid by argillitic rocks, close to one of the master faults bounding the tectonic depression of the Serchio Valley. Active and dormant landslides and deep-seated gravitational slope deformations affect the slope and make built-up areas and roads prone to a severe landslide hazard. In this area, a geologic-structural and geomorphological survey was performed, in order to improve the knowledge of mass movements, their preparation and triggering factors and their relations with morpho-structural conditions. The structural analysis did not detect any deformation rising from deep-seated mass movements. Distribution and orientation of the structural features conditioned the position of some mass movements, whose detachment areas and sliding surfaces partially correspond to weak zones of the slope (fault, joint zones). Seismicity and uplift during middle/late Pleistocene-Holocene (which caused, together with the quick deepening of drainage, an increased relief energy), together with climatic conditions, had a prominent role in the development of mass movements. Because of the high landslide hazard, researches were made in historic times, to find the activation dates and causes of the recognized landslides. An experimental landslide hazard zonation map was produced, based on the activity and the return period of mass movements.