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The deep structure of the Larderello‐Travale geothermal field from 3D microearthquake traveltime tomography
Author(s) -
Vanorio T.,
De Matteis R.,
Zollo A.,
Batini F.,
Fiordelisi A.,
Ciulli B.
Publication year - 2004
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl019432
Subject(s) - geology , microearthquake , geothermal gradient , seismology , petrology , transition zone , mineralogy , geophysics , induced seismicity
With the aim of exploring the deep structure of the Larderello‐Travale (LT) geothermal field, a high resolution 3‐D tomographic inversion of microearthquake traveltimes has been performed. Results show that the deep part of the Larderello‐Travale field is characterized by the presence of a structure having a velocity range of 6.0–6.5 km/s and a convex shape deepening towards the northeastern and the southeastern sides of the field. Earthquakes are mostly concentrated on the top of the high velocity structure and below the ‘ K horizon ’ implying a transition of rheological properties at depth. The reported dependence on time of t s ‐t p observed at one station located above an earthquake cluster suggests that the variation in pore fluid pressure might be responsible for the transition of rheological properties along the contact. In such an area, changes in pore fluid pressure might be related to time‐dependent hydraulic mechanisms that are very effective in crustal rocks at elevated temperatures.