HR: 09:45h
AN: S11E-08    [Abstracts]
TI: Body wave tomography of Iranian Plateau
AU: * Alinaghi, A
EM: ali@geol.ku.dk
AF: Geological Iinstitute, University of Copenhagen, Oster Voldgade 10, Copenhagen, 1350 Denmark
AU: Koulakov, I
EM: ivank@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg Haus E, Potsdam, 14473 Germany
AU: Thybo, H
EM: thybo@geol.ku.dk
AF: Geological Iinstitute, University of Copenhagen, Oster Voldgade 10, Copenhagen, 1350 Denmark
AB: The inverse teleseismic tomography approach has been adopted to study the P and S velocity structure of the crust and upper mantle across the Iranian Plateau. The method uses phase readings from earthquakes in a study area as reported by stations at teleseismic and regional distances to compute the velocity anomalies in the area. This use of source-receiver reciprocity allows tomographic studies of regions with sparse distribution of seismic stations, if only the region has sufficient seismicity. The input data for the algorithm are the arrival times of events located in Iran which were taken from the ISC catalogue (1964-1996). All the sources were located anew using a 1D spherical Earth model taking into account variable Moho depth and topography. The inversion provides relocation of events which is done simultaneously with calculation of velocity perturbations. With a series of synthetic tests we demonstrate the power of the algorithm to resolve both fancy and realistic anomalies using available earthquake sources and introducing measurement errors and outliers. The velocity anomalies show that the crust and upper mantle below the Iranian Plateau comprises a low velocity domain between the Arabian Plate and the Caspian Block, in agreement with models of the active Iranian plate trapped between the stable Turan plate in the north and the Arabian shield in the south. Our results show clear evidence of subduction at Makran in the southeastern corner of Iran where the oceanic crust of the Oman Sea subducts underneath the Iranian Plateau, a movement which is mainly aseismic. On the other hand, the subduction and collision of the two plates along the Zagros suture zone is highly seismic and in our images appear less consistent than the Makran region.
DE: 7200 SEISMOLOGY
SC: Seismology [S]
MN: 2004 AGU Fall Meeting