Engineering geologic assessment of the slope movements and liquefaction failures of the 23 October 2011 Van earthquake (<i>M</i><sub>w</sub>= 7.2)

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.

Van Gölü Bölgesi̇nde 2011 Yili Depremleri̇ni̇n Artçi Şok Seri̇si̇ Kirilma Karmaşiğina Yapisal Bağlanti(doğu Anadolu, Türki̇ye)

“…Soon after the Van earthquake, many geologists undertook field investigations of the surface ruptures and coseismic deformation (Irmak et al 2012;Koçyiğit 2012;Doğan and Karakaş 2013;Karakaş et al 2013;Doğan et al 2014). However, because of the occurrence of seismic-related surface ruptures, mass-wasting and landslides in the fields along the faults, the field investigations were limited to scattered sites and no information was obtained on geological nature of the ruptured area.…”

“…On October 23, 2011, a great thrust earthquake of magnitude Mw 7.1 occurred in the Lake Van area (Irmak et al 2012;Bayrak et al 2013;Elliott et al 2013;Acarel et al, 2014;Gori et al, 2014;Moro et al 2014;Toker 2015;Mackenzie et al, 2016) (Figure 1). The earthquake and its strong aftershocks activated the ~27-km-long Blind Thrust fault system that marks the accretionary wedge complex and the transition between the basins of Lake Van and Lake Erçek (Doğan and Karakaş 2013;Elliott et al 2013;Karakaş et al 2013;Doğan et al 2014). The multi-crustal occurrence and distribution of long-period aftershocks and focal mechanism of this larger event show a northeast-southwest striking rupture plane dipping towards the northwest (Irmak et al 2012;Toker 2013;Bayrak et al 2013;Fielding et al 2013;Utkucu et al 2013;Gori et al, 2014;Mackenzie et al, 2016).…”