Accurate relocation of İzmit earthquake (Mw = 7.4, 1999) aftershocks in Çınarcık Basin using double difference method

We relocated part of the aftershock activity in Çınarcık Basin and surrounding areas that are associated with the 1999 İzmit earthquake Mw 7.4. Double difference relocation algorithm is used to relocate the aftershocks. The data set was obtained from a temporary seismic network deployed 10 days after the main shock by cooperation between Boğaziçi University Kandilli Observatory and Earthquake Research Institute, LGIT (Grenoble), and IPGP (Paris). For a better station coverage, additional data set was obtained from a network operated by TUBITAK Marmara Research Center. Differential travel times were calculated using both arrival time readings and waveform cross correlation method. We relocated 1145 of the aftershocks and interpreted the results with emphasis on the Yalova and Tuzla cluster located within the Marmara Sea. The results show better focused seismicity patterns for the Yalova cluster, providing clear evidence for the proposed models. We present a revised location of the 1963 Çınarcık earthquake which took place in area of Yalova cluster. Finally we propose that the activity of Tuzla cluster represents a parallel subsidiary fault of the Main Marmara Fault.