Attenuation Tomography In East Marmara Region, Turkey

Attenuation tomography in East Marmara Region, Turkey

Abstract: The attenuation of body-wave amplitudes is sensitive to the seismic interfaces and fluid reservoirs in the crust. The 3-D P- and S-wave attenuation (Q_p^(−1) andQ_s^(−1)) presented the tomographic images of tectonic structure and fluid pathways between depths of 920 and 22000 m was determined in East Marmara region, Turkey. We used the software modified from The MuRAT code uses a source- and site-independent coda-normalization method based on P-to-coda and S-to-coda energy ratios. The software based on the Matlab inverts these data for the geometrical spreading factor and the spatially-dependent quality factors as Qp and Qs. In the Armutlu peninsula between depths of 0 and 15 km and in Tuzla between depths of 0 and 5 km, a low-velocity, high-attenuation is attributed to alteration zone and thick piles of sediments within Marmara Sea.

The results show that the seismicity located along the NAF zone and inside or under the fluid pathways produces an increase of the low-frequency energy ratios with travel time in the studying region. The results also provide spatial and frequency limits on the feasibility of attenuation tomography compared to the seismic velocity and Vp/Vs ratio in the region.