Moment Tensor Inversion of Earthquakes in Bartın and Surrounding Cities of Western Black Sea Region

Abstract:

In this study, focal mechanism of earthquakes in Bartın and sorroundings are analysed to determine the deformation and stress regime of the Western Black Sea region. The records of the earthquakes are obtained from the broadband seismic stations operated by Boğaziçi University Kandilli Observatory and Earthquake Research Institute National Earthquake Monitoring Center. In total 13 earthquakes with magnitudes (M_w) ranging between 3.5 and 4.8 are used. The source parameters are calculated by CMT (Centroid Moment Tensor) inversion method.

The results of this study show that 04.07.1972 M4.1 Saraydüzü-Bartın, 24.07.2013 M3.8 Amasra-Bartın, 24.11.2013 M4.8 Ulumescit-Bolu and 09.08.2008 M4.0 Karadeniz earthquakes indicate the presence of NE-SW directed reverse faulting mechanisms, in addition 28.01.2004 M3.6 Devrek-Zonguldak, 04.10.2005 M3.5 Yenice-Karabük, 12.11.2008 M4.1 Ericek-Bolu, 12.11.2008 M3.8 Aşağıkuzören-Bolu, 20.04.2006 M4.1 Amasra-Bartın, 04.09.2014 M4.0 Kayadibi-Bartın and 20.09.2014 M4.1 Bafra-Samsun earthquakes indicate the presence of NE-SW directed reverse oblique faulting mechanisms around the region. 16.08.2010 M3.9 Kozlu-Bolu, 13.05.2011 M3.9 Kızılağıl-Bolu, 20.12.2009 M3.9 Eskipazar-Karabük, 22.11.2009 M4.5 Daday-Kastamonu and 21.07.2013 M4.2 İhsangazi-Kastamonu earthquakes indicate right-lateral strike-slip faulting mechanism. 03.9.1968 Bartın earthquake is the strongest instrumentally recorded earthquake to occur along the Black Sea margin in the Northwestern Turkey. The focal mechanism solution of Bartın earthquake has been a controversial topic. The primary aim of this study is to shed light on these discussions. The focal mechanism solutions given by Kudo (1983) and Jackson and McKenzie (1984) state strike-slip faulting with reverse component, Şengör et al. (1983) state pure strike-slip faulting, on the other hand the solutions given by Alptekin et al. (1987) states that Bartın earthquake has pure reverse faulting mechanism. The focal mechanism solutions of the earthquakes studied in this study support the same structure as presented by Alptekin et al. (1987) and states that the region is under compressional tectonic regime.