Local earthquake tomography of the Larderello-Travale geothermal field

Abstract

The Larderello-Travale Geothermal Field in South-West Tuscany (Italy) is the oldest and among the most productive geothermal fields in the world. A new 3D model of seismic P-wave velocity (VP) of the upper crust beneath the geothermal field is derived by inverting a set of highly consistent travel-times from local-earthquakes. Results document a marked correlation of VP with previously described, high-reflectivity horizons. We also determined a low velocity body (VP ∼5 km s−1) culminating at depths of about 7 km, with estimated volume of 35–40 km3. Such low velocities are consistent with a granite at temperatures above 700 °C, thus in a partially-molten status.