| Te Marmara Sea, accommodating the fault segments of a major transform fault, is well known as a seismic gap along the North Anatolian Fault (NAF), running through the northern part of Turkey and connecting the East Anatolian convergent area with the Hellenic subduction zone (e.g., Pınar 1943; Toksöz et al. 1979; Pondard et al. 2007; Şengör et al. 2014). It is obvious from historical records spanning more than 2000 years that the region is subject to frequent strong shaking that is likely associated with tsunami waves, threatening heavily populated and industrialized locations (Ambraseys 2002; Erdik et al. 2004; Hébert et al. 2005). In the twentieth century, magnitude (M) 7-class earthquakes sequentially occurred from east to west along the NAF zone, as shown in Fig. ۱ (Stein et al. 1997). Te last two successive events hit the eastern Marmara region in August 17 and November 12, 1999, known as Izmit (Mw = ۷٫۵) and Düzce (Mw = ۷٫۲) earthquakes, respectively, killing about 20,000 people and devastating the region. On the other hand, at the western edge of Marmara Sea, an M ~ ۷ earthquake occurred in 1912, rupturing onshore and ofshore fault segments where 4–۵ m lateral displacements were measured (Armijo et al. 2005; Aksoy et al. 2010). Furthermore, in the Marmara Sea, it has been considered that the last M7 class earthquake occurred in 1766. With an average slip rate of 2 cm/year, several meters have accumulated over the past 250 years (Straub 1996; Meade et al. 2002). Based on a time-dependent model that includes the coseismic and post-seismic efects of the 1999 Kocaeli earthquake with moment magnitude Mw = ۷٫۴, Parsons (2004) concluded that the probability of an earthquake with Mw > ۷ in the Sea of Marmara near Istanbul is 35–۷۰% in the next 30 years. According to a 2011 study, an earthquake with Mw = ۷٫۲۵ on the Main Marmara Fault is expected to heavily damage or destroy 2–۴% of the near 1,000,000 buildings in Istanbul, which has a population of around 13 million, with 9–۱۵% of the buildings receiving medium damage and 20–۳۴% of the buildings lightly damaged (Erdik 2013). Te aim of this special issue is to gather information about the risk of another Marmara earthquake from the latest geophysical, geological, geotechnical, computational, and building science research results to discuss ways of mitigating disaster in advance. Te collection of 12 papers constituting this special issue is based on recent research on imaging the crustal structure, the geometry of the fault segments and their microseismicity features, source characteristics of large earthquakes inferred from historical seismograms, tsunami hazard assessment and mitigation studies, site response evaluations, and development of an integrated earthquake simulation system. |
