The North Anatolian Fault Zone: an Evaluation of Earthquake Hazard Parameters

Abstract

Turkey is located in one of the most actively deforming regions in the world. The tectonic in and around Turkey depends on relative motions between the African, the Aegean, the Arabian, the Anatolian, the Black Sea and the Eurasian plates (Kasapoglu & Toksoz, 1983). The neotectonics of Turkey is governed by three major elements (Bozkurt, 2001): (1) the Aegean–Cyprean Arc, a convergent plate boundary where the African Plate to the south is subducting beneath the Anatolian Plate to the north; (2) the dextral North Anatolian Fault Zone; and (3) the sinistral East Anatolian Fault Zone. Also, the sinistral Dead Sea Fault Zone has an important role. The North Anatolian Fault Zone (NAFZ) is one of the best-known dextral strike-slip faults in the world because of its remarkable seismic activity, extremely well developed surface expression and importance for the tectonics of eastern Mediterranean region. The NAFZ is a dextral strike-slip fault system that extends from eastern Turkey in the east, to the north Aegean in the west. Along much of its length, this fault zone consists of a few shorter sub-parallel fault strands that sometimes display an anastomosing pattern (Bozkurt, 2001). To the east, the NAFZ forms a typical triple-junction and joins with the sinistral East Anatolian Fault Zone at Karliova. The NAFZ does not terminate at the Karliova triple junction, but continues towards south east. The development of earthquake hazard assessment in Turkey has a substantial history and it has been produced considerable progress and innovation because Turkey has frequently suffered from major damaging earthquakes since the year 2000 BC. It has a long history of devastating earthquakes that have killed many thousands of people and caused economic loss, such as the Izmit (MS=7.8) and Duzce (MS=7.2) earthquakes of 17 August and 12 November 1999,respectively. As a result, a great number of local or regional earthquake hazard studies have been applied in recent years in order to present quantitative results on earthquake hazard of Turkey using the instrumental earthquake data. Several authors have used different statistical models to estimate the size of earthquake occurrences such as expected magnitude, intensity, ground acceleration, velocity or displacement. Amongst these studies are involving maximum seismic intensity, maximum magnitude and modal values (Bayrak et al., 2005, 2008a), peak ground acceleration (Erdik et al., 1999; Kayabali & Akin 2003), ω-upper bound magnitude of GIII distribution (Bayrak et al., 2008b), the index K-value defined as relative earthquake hazard scale (Bayrak et al., 2009).