RECENT CRUSTAL MOVEMENTS OF THE TRAVALE GEOTHERMAL AREA MEASURED BY CLASSICAL GEODETIC CONTROL NETWORK

In order to support and integrate an existing precise levelling control network, in the Travale geothermal area (Tuscany, Italy), a geodetic network was set up in 1973 to monitor the ground displacements occurring as natural neotectonic activity and induced by steam production in the geothermal field. This network consists of 7 benchmarks located across the main distensive fault system at the SW boundary of a regional graben-shaped tectonic feature that trends in Apenninic direction. The area is also affected by intensive geothermal exploitation. The net was measured several times with different types of geodetic methods: geometric and trigonometric levelling, distances and GPS. In the years 1988, 1990 and 1991 the distances were measured with the Mekometer ME 5000. The use of this very high precision distance meter allows to evidence a constant displacement trend also within a short period of measures.