AN INVESTIGATION OF THE MOHO TOPOGRAPHY BENEATH THE MARMARA REGION FROM AZIMUTHAL ANOMALIES

An investigation of the moho topography beneath the Marmara region from azimuthal anomalies

M.F. Özer, T. Taymaz, Ö. Kenar

Department of Geophysical Engineering, Kocaeli University, 41300 Kocaeli, TURKEY
Department  of  Geophysical  Engineering, Istanbul  Technical  University,  80626 Maslak, IstanbuI, TURKEY

Abstract

Accurate determinations of particle motions is a powerful tool in the investigation of seismic wave propagation. In these studies, the medium is assumed to be homogeneous and isotropic. While the medium is getting more heterogeneous and anisotropic some deviations are observed in polarization properties, angle of incidence and azimuth of the seismic waves. Therefore, information about the medium such as heterogeneity and anisotropy could be obtained from particle motion diagrams. We have tried to detennine the azimuthal anomalies of the region from the P-wave particle motions using three component short-period seismograms recorded from numerous earthquakes occurred in the vicinity of the Sea of Marmara. Azimuthal anomalies are generally considered to be related to lateral heterogeneities with the mediums. We have interpreted them in the sense of three dimensional dipping discontinuity (Moho) under the epicentre. Relative topography of the Moho discontinuity beneath the Marmara Region has been obtained using this new assumption.

Keywords: Marmara Sea, seismological studies, azimuthal anomalies

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