Local earthquake tomography of the Larderello-Travale geothermal field

• Published in: Geothermics Vol. 83; p. 101731
• Main Authors: Bagagli, M., Kissling, E., Piccinini, D., Saccorotti, G.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.2020; Elsevier Science Ltd
• Subjects: Earthquakes; Geothermal power; P waves; Seismic activity; Three dimensional models; Velocity; Wave velocity
• ISSN: 0375-6505; 1879-3576
• DOI: 10.1016/j.geothermics.2019.101731

•New P-wave velocity model for the geothermal area of Larderello-Travale (Italy) from local earthquake tomography.•Identification of a low-velocity anomaly at shallow depths (≈7 km) likely related to partially-molten granites.•The rock volume containing the productive horizon displays P-wave velocity values between 5 and 5.5 km s−1. 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.