HR: 0830h
AN: S31E-0805    [PDF]
TI: Upper Mantle Velocity Structure Beneath Eastern Anatolian Plateau and Surrounding Regions
AU: * Sandvol, E
EM: sandvole@missouri.edu
AF: Department of Geological Sciences, University of Missouri, Columbia, MO 65211 United States
AU: Zor, E
EM: ekrem@nmsu.edu
AF: Department of Physics, New Mexico State University, Las Cruces, NM 88003 United States
AU: Forsyth, D
EM: donald_forsyth@brown.edu
AF: Department of Geological Sciences, Brown University, Providence, RI 02912 United States
AU: Hearn, T
EM: thearn@nmsu.edu
AF: Department of Physics, New Mexico State University, Las Cruces, NM 88003 United States
AU: Turkelli, N
EM: turkelli@boun.edu.tr
AF: Kandilli Observatory and Earthquake Research Institute, Bogazici University, Istanbul, 81221 Turkey
AB: The Eastern Turkey Seismic Experiment (ETSE) was designed to image the crustal and upper mantle velocity structure beneath the northernmost Arabian plate and beneath the Anatolian Plateau, constraining geodynamic models for young continent-continent collision. ETSE was composed of a 29 station broadband PASSCAL array which was deployed from October 1999 until August 2001. We have measured Rayleigh wave phase velocities across the Anatolian plateau using 45 teleseismic and regional events. We used a method that approximates the wavefield from each earthquake as the sum of two interfering plane waves to map Rayleigh wave phase velocities for periods between 30 and 140 seconds. The optimal one dimensional velocity model suggests that there is little, if any, lithospheric mantle beneath the Eastern Anatolian plateau. The Rayleigh wave phase velocity maps are consistent with the Bitlis suture?s marking an abrupt change in the lithospheric mantle velocity structure. Tomographic mapping of the Rayleigh wave phase velocities suggests that the uppermost mantle ultra-low velocity zone is underlain by relatively normal to slightly low velocity mantle. This finding is consistent with our preliminary three dimensional P-wave velocity model that was obtained using teleseismic body wave tomography. The preliminary P-wave model does not show a clear contrast in mantle properties across the Bitlis suture. Teleseismic shear wave splitting indicates that there is a relatively uniform northeast fast direction throughout the plateau. Across the eastern portion of the Anatolian plateau, there appears to be some correlation between very slow mantle lid velocity and large splitting lag times. We are investigating the depth extent of the azimuthal anisotropy beneath the eastern Anatolian plateau using Rayleigh wave phase velocities.
DE: 7203 Body wave propagation
DE: 7218 Lithosphere and upper mantle
DE: 7255 Surface waves and free oscillations
DE: 8102 Continental contractional orogenic belts
DE: 8180 Tomography
SC: Seismology [S]
MN: 2003 Fall Meeting