HR: 0800h
AN: S51A-0991    [Abstracts]
TI: Finite Frequency Tomography of the Patras Area (Gulf of Corinth,Greece)
AU: * GAUTIER, S
EM: gautier@dstu.univ-monpt2.fr
AF: Laboratoire de Tectonophysique Université de Montpellier 2, Place Eugene Bataillon CC 049, Montpellier, 34095 France
AU: NOLET, G
EM: nolet@princeton.edu
AF: Department of Geosciences University of Princeton, 320 Guyot Hall, Princeton, NJ 08544 United States
AU: VIRIEUX, J
EM: viri@geoazur.unice.fr
AF: Géosciences Azur Université de Nice-Sophia Antipolis, 250, R. A. Einstein, Valbonne, 06560 France
AB: The Gulf of Corinth is the most active rifting zone of the Mediterranean region. Despite many studies, the crustal structure of this region is still a debating subject. In the western part of the Gulf where we focus our study, previous tomographic studies point out a complex crustal structure and a low-dip surface that may accommodate the deformation. In this study, we include the sensitivity kernels in a 3D tomographic method. The influence of the frequency content will be analyzed when considering variable velocity structure. An accurate reconstruction of a 3D high-resolved images of the mid-crust beneath the Gulf of Corinth will improve our understanding of the rifting process in this area. In order to do so, we perform accurate estimation of both rays and travel-times between source/receiver and diffraction points using graph theory and an additional bending. Then, we estimate the amplitude using paraxial theory on these rays, amplitude estimation which are required in the sensitivity kernel. We invert both the velocity and the hypocenter parameters, using these so-called banana-doughnut kernels. Our dataset comprises of 451 local events with 9236 P- and 7523 S- first-arrival times. The events were recorded in the western part of the Gulf (Aigion area) in the framework of the 3F-Corinth project. We first analyze the impact of the crustal heterogeneities on the sensitivity kernels. Then, we compare our images with previous tomographic results in order to illustrate what brings inside our images the finite-frequency effects compared to features introduced by the high frequency limit which is the ray theory.
DE: 7203 Body waves
DE: 7219 Seismic monitoring and test-ban treaty verification
DE: 7270 Tomography (6982, 8180)
DE: 7290 Computational seismology
SC: Seismology [S]
MN: Fall Meeting 2005