Crustal deformation and gravity changes during the first ten years of exploitation of the new travale — radicondoli geothermal field, Italy

Abstract

The results of precise levelling measurements on a specially constructed network of benchmarks in the Travale geothermal area (Tuscany, Italy) revealed that the central part of this area is subsiding and that the average rate of subsidence in the period 1973–1983 was 20–25 mm/year. Three series of horizontal distance measurements were carried out (1980, 1981, 1982) to monitor variations in the coordinates of the bases of a horizontal control net. The variations noted in this time interval range between 13 and 36 mm, slightly exceeding the semi-axis values of their error ellipses. A series of gravity measurements was carried out annually between 1979 and 1982 on a network of gravity benchmarks coinciding with part of the topographic benchmarks. The g variations observed reached a maximum of 40 μGal. A tentative correlation of these data with field exploitation data indicates a possible means of interpreting the variations observed during these surveys.