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Assessment of seismic hazard in the Erzincan (Turkey) region: construction of local velocity models and evaluation of potential ground motions

2015-01-01
Askan Gündoğan, Ayşegül
Karim Zadeh Naghshineh, Shaghayegh
Asten, Michael
Kilic, Nazan
Sisman, Fatma Nurten
Erkmen, Cenk
The fundamental step in estimation of seismic damage and losses in urban areas is identification of regional potential seismic hazard. The accuracy of seismic analyses depends on the reliability of the local input parameters used in the corresponding hazard and loss models. This paper presents detailed seismic hazard analyses for an earthquake-prone region using locally derived source and site parameters. Main components of this study are construction of local seismic velocity models, probabilistic and deterministic seismic hazard analyses, and estimation of corresponding potential ground motions. The study area is Erzincan, which is a city on the eastern part of the North Anatolian Fault Zone. Located at a triple junction of major fault systems within a basin structure, Erzincan experienced major events (Ms similar to 8.0) in 1939 and (Mw = 6.6) in 1992. This study presents the first discussion in the literature on site-specific probabilistic and deterministic hazard analyses for Erzincan. Using locally derived input parameters in site response modeling and hazard analyses, the earthquake potential of Erzincan is investigated in detail. Probabilistic seismic hazard analyses with a hybrid source model composed mainly of line sources show that for a return period of 475 years, the maximum peak ground acceleration value in the Erzincan city center is computed to be almost 1 g. On the other hand, probabilistic hazard analyses with only area sources yield ground motion amplitudes that are almost half of those obtained by the hybrid model. The deterministic hazard analyses also show that peak ground acceleration in the city center for a scenario event of Mw = 7.0 reaches 1.25 g at a soft soil site located at 2 km in distance from the fault plane. In summary, numerical results obtained with locally derived input parameters indicate that Erzincan has significant potential for hazard in terms of both local earthquake occurrence and site amplifications.