Source mechanism of the 23 October, 2011, Van (Turkey) earthquake (Mw=7.1) and aftershocks with its tectonic implications

This study has investigated the rupture process of the 23 October, 2011, Van (Turkey) earthquake (M-w = 7.1) by using inversion of teleseismic waveform analysis and its tectonic implications. Focal parameters of the main shock and 21 aftershocks were obtained by using the first motion polarities of regional P-waves. The first results for the source rupture process were derived from broadband teleseismic P-waves. The main outcomes of the analysis are: (a) the main rupture is located around the initial break point, and the maximum slip amount was 3.6 m; (b) the size of the main fault plane area was about 40 km in length and 20 km in width, the duration of rupture was approximately 19 seconds and the seismic moment of the earthquake was estimated to be 5.53 x 10(19) N m (M-w = 7.1); (c) the rupture gradually expanded near the hypocenter and propagated both northeast and southwest, but mainly to the southwest. Tectonic implications of the earthquake were defined by field observations. The 23 October, 2011, Van earthquake occurred on a main thrust fault plane trending NE-SW between Lake Van and Lake Ercek located in the East Anatolian compressional province. This main fault plane and the secondary structural elements were generated by a continental-continental collision taking place in a region located 200 km north of the the Bitlis-Zagros Suture Zone.