A New Passive Tomography of the Aigion Area (Gulf of Corinth, Greece) from the 2002 Data Set - Archive ouverte HAL Access content directly
Journal Articles Pure and Applied Geophysics Year : 2006

A New Passive Tomography of the Aigion Area (Gulf of Corinth, Greece) from the 2002 Data Set

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Abstract

We present the results of a tomographic study performed in the framework of the 3F-Corinth project. The aim of this work is to better understand the rifting process by imaging the crustal structure of the western Gulf of Corinth. Forty-nine stations were deployed for a period of six months, allowing us to monitor the microseismicity. Delayed P and S first-arrival times have been simultaneously inverted for both hypocenter locations and 3-D velocity distributions. We use an improved linearized tomography method based on an accurate finite-difference travel-time computation to invert the data set. The obtained Vp and Vs models confirm the presence of a two-layer vertical structure characterized by a sharp velocity gradient lying at 5–7 km depth, which may be interpreted as a lithological contrast. The shallower part of the crust (down to 5 km depth) is controlled by the N-S extension and lacks seismicity. The deeper part (7–13 km depth) matches the seismogenic zone and is characterized by faster and more heterogeneous anomalies. In this zone, the background seismicity reveals a low-angle active surface dipping about 20° toward the north and striking WNW-ESE. The position of this active structure is consistent with both high Vp/Vs and low Vp.Vs anomalies identified at 8–12 km depth and suggesting a highly fracturated and fluid-saturated zone. Both the geometry of the active structure beneath the gulf and the presence of fluids at 8–12 km depth are in accordance with a low-angle detachment model for the western part of the Gulf of Corinth.

Dates and versions

insu-00355296 , version 1 (22-01-2009)

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Cite

S. Gautier, D. Latorre, J. Virieux, Anne Deschamps, C. Skarpelos, et al.. A New Passive Tomography of the Aigion Area (Gulf of Corinth, Greece) from the 2002 Data Set. Pure and Applied Geophysics, 2006, 163 (2-3), pp.431 à 453. ⟨10.1007/s00024-005-0033-7⟩. ⟨insu-00355296⟩
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