Individuazione di zone a rischio sinkhole, metodologie operative a Camaiore (LU)

Abstract

In the last decades, in the area of Camaiore Plain (Lucca), a series of surveys was planned and carried out, in order to better understand the causes of the collapse. In the first time, several geological, geochemical, seismic, geoeletrical and geognostic surveys were those aimed at acquiring both surface and underground geological features of the area; later the sinkholes risk areas were monitoring by Interferometric method. A gravity investigation was carried out in the area; 3D inverse modeling was found that the rocky substratum in the sinkhole zone is made up of cavernous limestones, intensely fractured and intersected by various direct faults. The bedrock is buried by thick alluvial successions, which reach a thickness of about 14O m in the area. For this reason microgravity prospecting has been applied in order to identify the sink- holes risk areas and any other geological conditions similar to those leading to the 1995 collapse. The map of the Residual Anomalies of Camaiore town, shows different areal distribution of gravity minimum zones connectable to superficial causes (75 meters depth). The negative gravity anomalies can be explained with the lower density sediments (gravelly, sandy and silty-argillaceous alluvial deposits). The Camaiore area have been monitored by Interferometric Synthetic Aperture Radar (which measures surface elevation changes in a wide spatial resolution) and Global Positioning System (which is very accurate for measuring position changes in specific positions) technique. Then raining days, the uplifting area corresponds to that were the negative anomalies occurred.