Source mechanism and stress analysis of 23 October 2011 Van Earthquake (Mw=7.1) and aftershocks

摘要

On 23 October 2011 at 1341 local time, a strong earthquake (Mw=7.1) occurred east of Lake Van (KOERI; Kandilli Observatory and Earthquake Research Institute). The focal parameters of the main shock and 29 aftershocks with M≥4.0 were obtained from regional broadband seismic data from KOERI network by using Regional Moment Tensor Inversion Code (Dreger 2002). It is confirmed that the main shock had thrust faulting mechanism. The stress tensor analysis was completed using the focal mechanism solutions and the software developed by (Gephart Comp Geosci 16: 953-989, 1990). The maximum principal stress (P compressional) of the main shock is aligned in a N-S (NNW/SSE) direction and the tensional axis (T dilatation) is aligned in an E-W(ENE-WSW) direction. The b value is calculated as 0.96 using the maximum likelihood method (Utsu 1999).