Seismic Hazard in the Marmara Region, Northwest Turkey

Abstract

The North Anatolian Fault Zone (NAFZ) is a 1500 km-long dextral transform fault that accommodates western extrusion of Anatolian plate resulting from the collision of the Arabian plate in the eastern Anatolia along with sinistral East Anatolian Fault Zone (Reilinger et al. 2006) (Fig. 1a). The North Anatolian Fault Zone bifurcates into and extends as three fault strands, namely the Northern, Middle and Southern Strands, in the Marmara Region (Barka and Kadinsky-Cade (1988); Saroglu et al. 1992; Armijo et al. 2005) (Fig. 1). The both strands have produced tens of destructive large earthquakes over the past twenty centuries as revealed from the historical sources (Ambraseys, 2002), indicating high seismic activity in the region. In the present study, seismic hazard in the Marmara Region is assessed by examining the historical and instrumental period seismicity and the paleoseismological studies. Also, the b value of the frequency-magnitude distribution (FMD) of earthquakes (Gutenberg and Richter (1944)) in three selected areas (called as Eastern, Western and Southern Areas) in the region is mapped from the declustered background seismicity prior to the August 17, 1999 Izmit earthquake, covering the time period between 1981 and 1999 (Fig. 1).