Abstract
Abstract. On 23 October 2011, a Mw = 7.2 earthquake occurred in the Van Province in eastern Turkey, killing 604 people. The earthquake was triggered by a thrust fault due to a compression stress in the region, and caused extensive damage over a large area. Many structures in the earthquake region collapsed, and the damage spread from the city of Van to the town of Erciş, in a distance of 60 km. The earthquake generated several slope movements and liquefaction failures in the region, and this study evaluates these processes from the perspective of engineering geology, and presents field and laboratory results related to these processes. Attenuation relationships were used for estimation of peak ground accelerations (PGAs), and an empirical liquefaction evaluation method employing ground accelerations was used to define threshold accelerations initiating the liquefaction. The results demonstrate that landslides were widespread and more frequently observed in the field in comparison with earthflows and rockfalls. Flow-type liquefaction and lateral spreading was found to be widespread and more common than the liquefaction-related settlement. The minimum threshold acceleration value for the initiation of soil liquefaction was calculated to be 188.87 cm s−2 (~0.19 g) in the earthquake region. Laboratory results indicated that the soil liquefaction was closely associated with grain size. The slope instabilities, liquefaction and associated ground failures occurred mainly in rural areas, and their impact on structures was quite low as compared to the human loss and structural damage by the earthquake.
Highlights
The Van earthquake, which occurred in East Anatolia, and laboratory results related to these processes
The Van earthquake occurred in the Lake Van basin located in the East Anatolian region of Turkey, located approximately 60 km north of Bitlis–Zagros suture zone (BZSZ), constituting a collision boundary between the Arabian plate in the south and the Eurasian plate in the north (Fig. 1)
As a result of the increased number of stations and the database of strong ground motion after the 1999 ̇Izmit (Golcuk) (Mw = 7.4) and Duzce (Mw = 7.2) earthquakes, new specific attenuation relationships have been developed for peak ground accelerations (PGAs) and spectral accelerations (SAs) in Turkey (Gulkan and Kalkan, 2002; Ozbey et al, 2004; Ulusay et al, 2004; Akyol and Karagoz 2009; Ulutasand Ozer, 2010; Ulutaset al., 2011)
Summary
The Van earthquake occurred in the Lake Van basin located in the East Anatolian region of Turkey, located approximately 60 km north of Bitlis–Zagros suture zone (BZSZ), constituting a collision boundary between the Arabian plate in the south and the Eurasian plate in the north (Fig. 1). Subduction to the north, the BZSZ constitutes the boundary between the Arabian and Eurasian plates This zone turned into a collision zone surrounded by the north-dipping 3 Geomorphology of the Van region thrust faults at the beginning of the early Miocene (Sengor et al, 2008). Lake Van is borpecially transtensional normal faults in the region (Sengor et dered on the south by a high mountain range, while the east al., 1985). The slope and liquefaction failures are closely related to the geomorphological setting and climatic conditions
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