M. Alper Şengül, Şule Gürboğa, İsmail Akkaya and Ali Özvan
The area of investigation is located on the south-eastern shore of Lake Van in Eastern Turkey where a destructive earthquake took place on 23rd October, 2011 (Mw = 7.1). Following the earthquake, different source mechanisms, deformations, and types of faulting have been suggested by different scientists. In this research, Edremit district and vicinities located on the southern side of Van have been investigated to understand the deformation pattern in a travertine (400 ka) formation on the surface, and its structural and stratigraphic relationships with the main faults under the surface by using two-dimensional (2D) Electrical Resistivity Tomography (ERT) profiles. The results were used to document the deformation pattern of rocks with the Miocene and the Holocene (400 ka travertine) in ages. By means of the investigations, deformation patterns implying the tectonic regimes during the Oligocene–Miocene–Pliocene, and Quaternary time have been determined. According to detailed field work, the local principal stress direction has been defined as approximately N 35° W. This is also supported by the joint set and slip-plane data. Moreover, Oligocene– Miocene units provide a similar principal stress direction. Our data suggest that the southern part of the Elmalık fault is characteristic of reverse faults rather than of the normal fault system that has been previously reported. In addition, the Gürpınar fault controlling the deformation patterns of the region is a reverse fault with dextral component.