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Descartes, France

Calo M.,EOST Institute | Calo M.,CFTA Institute | Dorbath C.,EOST Institute | Luzio D.,CFTA Institute | And 3 more authors.
Geophysical Journal International | Year: 2012

In this study we have determined detailed Vp and Vs seismic velocity models of the Ionian lithosphere subducting beneath the Tyrrhenian basin and of the surrounding mantle, by applying a post-processing technique to a large sample of local earthquake tomography studies. Our seismic velocity models permit us to infer the presence of low velocity anomalies within the slab, which we interpret as regions that are partially hydrated by fluids released during the subduction process. A petrological interpretation of the velocity anomalies gives new details on the magmatism of the volcanic Aeolian arc. Furthermore our velocity models provide a more detailed description of the boundary of the slab and its connection with the large seismically active Tindari-Letojanni strike slip system. Finally these results allow describing in detail some features of the slab as the presence of lateral and vertical tears. In conclusion, the obtained models provide some constraints for inferences on mantle circulation, and on the geodynamical evolution of the central-western Mediterranean. © 2012 The Authors Geophysical Journal International © 2012 RAS. Source

Calo M.,EOST Institute | Kinnaert X.,EOST Institute | Kinnaert X.,Karlsruhe Institute of Technology | Dorbath C.,EOST Institute
Geophysical Journal International | Year: 2013

The aim of this work is to assess the feasibility of the noise-cross correlation tomography method for imaging and detecting potential geothermal reservoirs even in highly urbanised areas. We tested the noise correlation method to reconstruct the shape of the Soutlz-sous- Forêts enhanced geothermal system (northern Alsace, France). We inverted Rayleigh waves (RWs) reconstructed from cross-correlations of 15 months of ambient seismic noise recorded by a seismic array installed around the Soutlz geothermal power plant. By correlating noise records between 22 receivers, we reconstructed RWs with sufficient signal-to-noise ratio for 231 interstation paths. The reconstructed waveforms were used to estimate group velocity dispersion curves at periods between 1.0 and 5.0 s. The results were inverted for 2-D group velocity maps, and finally for a 3-D S-wave velocity model from 0 to 5.2 km depth. Our results clearly show the presence of low velocity bodies in the crystalline basement below the Soultz power plant at depth of 4-5 km, and at shallower depth (2.5-3.5 km) beneath the Rittershoffen and Woerth villages. These observations, in agreement with some previous studies, confirm that our procedure is suitable for geothermal exploration. Furthermore, the model presented here provides some suggestions to improve the existing geothermal power plant and inferences for further explorations in the area. © The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society. Source

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