HR: 08:30h
AN: S21C-03    [PDF]
TI: Seismic Refraction Experiments In The Eastern Marmara Region, Western Part Of The North Anatolian Fault Zone
AU: * Bekler, T
EM: bekler@boun.edu.tr
AF: Bogazici University, KOERI, Cengelkoy, Istanbul, 81220 Turkey
AU: Gurbuz, C
EM: gurbuz@boun.edu.tr
AF: Bogazici University, KOERI, Cengelkoy, Istanbul, 81220 Turkey
AB: The velocity-depth model of the eastern Marmara region is determined using controlled source data. In order to obtain a reliable velocity structure, seismic modeling was performed in two stages; first, forward modeling was applied to controlled source data by means of basically two-dimensional ray tracing technique. Then, traveltime inversion was applied to the data obtained from seismic refraction experiments in the eastern Marmara region. A two-dimensional P wave velocity structure was aimed to obtain from the refraction profiles. Two quarry blasts and one controlled source data were collected. In addition to those recordings, a survey conducted by Turkish-German Group and three previous quarry blast experiments were re-analyzed. Velocity model for the Marmara region shows a four-layered structure of 20 km thick. Results of the calculated velocity structure and known geological information from the region might probably listed as: The first layer corresponds to quaternary sediments, second layer consist of a sequence of thick sediments including Eocene aged volcano-sediments, Mesozoic aged sedimentary rocks and Paleozoic aged thick sedimentary rocks including carbonates. Below this second layer there are two more layers. Third layer might consist of granitic rocks and fourth layer shows high seismic velocities, which indicate that this layer represents more basic rocks. The seismic refraction surveys provided a good estimation of seismic velocity model for the region. The overall pictures of the all controlled source experiments indicate that Pg velocities are ranging between 5.4 - 5.7 km/s and Pn wave velocity is about 8.0 km/s for the eastern Marmara region. This high Pn velocity is consistent with the earthquake data interpretation results. Evidence from quarry blast, explosion data and previous studies strongly suggest that along the western end of the North Anatolian Fault has a complexity in the local velocity structure. This issue is addressed here in conjunction with the determination of models for two-dimensional structure of the upper crust in the eastern Marmara region
DE: 7205 Continental crust (1242)
DE: 7230 Seismicity and seismotectonics
DE: 7260 Theory and modeling
DE: 8123 Dynamics, seismotectonics
SC: Seismology [S]
MN: 2003 Fall Meeting