Date

2011-01-01

Author

Özkaymak, Çağlar
Sözbilir, Hasan
Bozkurt, Erdin
Dirik, Ramazan Kadir
Topal, Tamer
Alan, Hüseyin
Dündar, Çağlan

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This study aims to explore the origin and location of the October 23, 2011 Tabanlı-Van earthquake within active tectonic framework of Van city and its surroundings. Field-based studies have been done just after the Tabanlı-Van earthquake, and then geometry and type of observed deformational structures were evaluated and integrated with the results of previous active tectonic studies in the region. The observed structures can, based on seismic geomorphological indicators, be grouped into two main categories: (1) seismotectonic landforms related to tectonic stress, and (2) seismogravitational landforms related to seismic shaking and earth’s gravity. Seismotectonic landforms are common within a 10-km-long deformation zone located between Van Lake and Erçek Lake. These occurs as N50–70°E trending synclines and anticlines, most commonly in the area between Bardakçı and Topaktaş villages. Seismogravitational landforms are common in water-saturated sediments of Lake Van, particularly along its eastern margin; they are mostly liquefaction-induced features and are expressed in the form of lateral spreading, ground subsidence, and mass movement. Reverse fault planes deforming and displacing Upper Pliocene-Pleistocene sediments form the other group of common structures in the region. They trend in N50–70°E direction direction and dip at 45-50° to the north; they are oblique structures with sinistral strike-slip components. Similar active faults were mapped by Özkaymak (2003) at three locations to the north of Van city center: north of Beyüzümü village, near the main gate of the Yüzüncü Yıl University Zeve Campus and southern part of the Aşıt village. Evaluation of previously mapped fault segments and recent observations in the deformation zone are consistent with an approximately 10 km wide active thrust fault zone that comprises, at least, five N50–70°E striking and north-diping (ca. 47°) fault segments. Kinematics of these faults is consistent with fault plane solutions of 23 October, 2011 Tabanlı-Van earthquake. We suggest that newly formed and/or reactived fault segments in this fault zone were the source of the 23 October, 2011 Tabanlı-Van earthquake. The absence of surface rupture(s) is attributed to the geometry of a blind thrust. According to geological mapping and kinematic analyses, the active tectonics of the region is the manifestation of, in addition to ENE-WSW-striking thrust faulting, NNW-SSE-directed compression as expressed by NE-SW-trending sinistral strike-slip faulting, NW-SE-trending dextral strike-slip faulting and N-S-trending normal faulting.

Subject Keywords

Aktif tektonik, Doğu Anadolu, Gömülü bindirme, Sismik jeomorfoloji, Tabanlı–Van depremi, Active tectonics, East Anatolia, Blind thrust, Seismic geomorphology, Tabanlı-Van earthquake

URI

https://hdl.handle.net/11511/85636
https://dergipark.org.tr/tr/download/article-file/280833

Collections

Department of Geological Engineering, Article