The Significance of Crustal Velocity Model in Moment Tensor Solutions: A Case Study of Yedisu Earthquakes

Abstract

The North Anatolian Fault Zone is (NAFZ), which is one of the world's most active seismic structures, runs along the northern part of Turkey. Seismic velocity structure of the crust in the seismically active regions such as NAFZ plays an important role not only in the accurate hypocenter location and characterization of earthquakes but also in the determination of source mechanism and fault properties. We investigated the Moment Tensor (MT) solutions of earthquakes with respect to different crustal velocity models. MT solutions of earthquakes (M>4.0) occurred in Yedisu segment, which is located near the intersection of North Anatolian Fault Zone and East Anatolian Fault Zone were examined in the study. MT solutions were calculated by full waveform inversion using the software package ISOLA. Different crustal velocity models and hypocenter location parameters were tested during the computation of MT solutions. All observations are very well justified in terms of moment tensor resolvability (a well-posed problem with a low condition number), satisfactory fit between observed and synthetic waveforms, and large doublecouple percentages. Obtained results provide valuable information in understanding the seismotectonic behaviour of one of the most seismically active regions along the NAFZ.