HR: 08:30h
AN: S41E-03    [Abstracts]
TI: The Crustal And Upper Mantle Shear Wave Velocity Structure Beneath Eastern Turkey Using Inversion of Surface Wave Dispersion
AU: * Can, B
EM: birsenc@boun.edu.tr
AF: Bogazici University, Kandilli Observatory and Earthquake Research Institute, Cengelkoy, Istanbul, 34684 Turkey
AU: Gurbuz, C
EM: gurbuz@boun.edu.tr
AF: Bogazici University, Kandilli Observatory and Earthquake Research Institute, Cengelkoy, Istanbul, 34684 Turkey
AB: In this study, shear wave velocity structure model of the crust and upper mantle across a broad portion of Eastern Turkey was investigated using measurements of the group and phase velocity dispersion curves of fundamental mode Rayleigh and Love waves. The data used correspond to broadband 3 component records obtained during October 1999 to August 2001 Eastern Turkey Seismic Experiment (ETSE). ETSE was designed to investigate the Eurasian-Arabian plate margins across the Bitlis suture and East and North Anatolian Fault zones. The experiment was the result of a collaborative effort between the Bogazici and Cornell Universities. Instrumentation was provided by PASSCAL, and consisted of 29 REFTEK 72A recorder, with 28 Streckeisen STS-2 sensors and one Guralp CMG-3T sensor. Earthquakes were selected that were located at distances of 15 degree to 90 degree azimuths from the center of the array with large signal to noise ratio. The two horizontal seismograms were then rotated from north and east to radial and transverse components. Once the radial and transverse component of motion are obtained, the seismograms are then decimated from 40 sps to 10 sps. In obtaining the group velocity curves, the Multiple Filter Technique (MFT) and the Phase Matched Filter Technique (PMF) are used. The combination of these two techniques permits isolation of the fundamental mode to obtain cleaner group velocity dispersion curves. MFT is an analytical method to compute and obtain group velocity dispersion curves for a specific mode from complex multimode dispersion signal. After applying the MFT, the dispersion curves are used as an input for the PMF. With the application of the PMF to the data set, an improvement of the group velocity dispersion curves and also isolation of the fundamental mode are obtained. Then the noise and the influence of higher modes are significantly reduced. This allows to reapply the MFT and calculate a more accurate group velocity dispersion curve of the fundamental mode. To obtain phase velocity dispersion curves these simpler signals are used. Both group and phase velocity Love and Rayleigh waves have been incorpareted simultaneously into shear wave velocity inversion. Results imply a different shear wave velocity disribution within the region. In the middle of the array there is a low velocity zone. Due to the complexity of the region the thickness of the crust varies. The crust is thin at the northeastern part of the Anatolian Plateau.
DE: 7200 SEISMOLOGY
DE: 7205 Continental crust (1219)
DE: 7218 Lithosphere (1236)
DE: 7255 Surface waves and free oscillations
SC: Seismology [S]
MN: Fall Meeting 2005