Crustal Movements and Deformations in Eastern Turkey in Connection with the Van Earthquake (October 23, 2011, Мw = 7.2): Study from GPS Data

Abstract—A devastating earthquake with magnitude Mw = 7.2 occurred in the Van region, Eastern Turkey, on October 23, 2011. This study analyzes the characteristics of surface deformation before, during, and after the earthquake. The data from 300 × 300 km2 permanent GPS network are used to quantitatively estimate surface deformations in the epicentral zone of the earthquake in the interval from January 16, 2009 to October 29, 2012 with daily time resolution. The dilatation, total shear, horizontal and vertical displacements are determined approximately three years before and one year after the 2011 Van earthquake. The spatial distributions of strains for each day are combined into a video to track the variations in the deformation process before and after the earthquake. The anomalous deformations are revealed a few months before the earthquake at a distance of about 100 km from the future epicenter. The evolution of the motions and deformations in the study region indicates a probable connection between the development of anomalous strains in the Varto fault zone and Bitlis–Zagros suture zone and the preparation of the Van earthquake. This suggests that preparatory deformation processes may take place at distances of dozens and hundreds km from the future seismic source.