| Abstract: | In 1980 and 1982 the Laboratory of Applied Geophysics of the C.N.R.S. attempted to establish, by magnetic differential sounding, a possible conductivity anomaly linked with the geothermal field of Travale, Tuscany. Some 25 sites were occupied along two profiles, one between Siena and Populonia, near Piombino, the other between Siena and Cecina. An important anomaly of the transient magnetic field (some 15% of the normal field) was discovered in 1980 between Gerfalco (in the SW) and Frosini (in the NE). It exactly covers the geothermal area of Travale. The direction of the telluric currents causing the anomaly is parallel to the magnetic meridian and their maximum depth is of some 2000 m. The 1982 campaign showed that in the north of Travale, anomalous currents move in a NW - SE direction or even completely EW (SW of Volterra) and meet in the sea near Livorno. One possible interpretation of these phenomena as a whole is to assume the presence of very conductive layers between Larderello and Travale. The currents which circulate parallel to the coast are channelled locally by this structure, which could be closely linked with the geothermal field. |
