Magnitude 7.2 earthquake Eastern Turkey
23 October 2011
The earthquake of October 23, 2011 (10:41 UTC) occurred in Eastern Turkey approximately 20 km north of the city of Van with almost 350 000 inhabitants situated along the eastern side of the largest lake in Turkey with the same name. The earthquake had a magnitude of 7.2 (USGS), which has a significant destruction potential. Although the first estimate of casualties is low, this number is expected to increase based on the fact that the same area was destroyed by an eartquake in November 24, 1976 with a magnitude of 7.5 (KOERI) which caused 3840 casualties and 9232 building collapse. There were two other destructive earthquakes in the region in April 2, 1647 and May 30, 1881 (KOERI).
The earthquake occurred on a low-angle thrust fault dipping gently towards north, which is one of the several similar structures in this region. These thrust-faulting events with reverse focal mechanisms are the result of N-S convergence between the Arabian plate in the south and the Anatolian microplate in the north. Currently a number of aftershocks are being registered (more that 88 aftershocks were recorded within the first hours).
Turkey is prone to large earthquakes along the two main geological structures that run across the country, namely the North Anatolian and East Anatolian fault systems which merge in a triple junction to the west of the Lake Van, in the Karliova area. These structures produce mainly strike-slip faulting and are therefore different in their deformational style with respect to the earthquake of October 23, 2011, which had a thrust mechanism.