VAN GÖLÜ BÖLGESİNDE 2011 YILI DEPREMLERİNİN ARTÇI ŞOK SERİSİ KIRILMA KARMAŞIĞINA YAPISAL BAĞLANTI(DOĞU ANADOLU, TÜRKİYE)

Abstract

This study presents an analysis of the structural coupling to the two large destructive earthquakes that occurred in Lake Van area on October 23 (Mw 7.1), and November 9 (Mw 5.6), 2011, together with the azimuth-dependent distribution of the seismic activity and microseismicity clusters after the mainshocks, associated with the complex rupture processes of the aftershock sequence. The aftershock sequences after the two mainshocks were linked to the local crustal faults beneath Lake Van area, followed successively and produced unusually intense activity and significant damage in the area. The main purposes of this study are to document the spatial and temporal distribution and evolution of the October 23, 2011 aftershock hypocenters and the azimuth-dependent distribution of seismic activity, and to understand the structural character of the aftershock sequence using the distributional and evolutional patterns of the aftershock hypocenters. A total of 10,000 aftershocks were obtained from seismic data with a high signal-to-noise ratio collected over three years from October 23, 2011 to March 17, 2014. These aftershocks were relocated for the time periods from November 2011 through March 2012 to March 2014 and ≈ 5000 aftershocks were retained in the depth versus distance cross-sections to detect the clusters in the first step of study (November 2011-March 2012). The focal depth distribution of the aftershock clusters, the migration of hypocenter activity and microseismicity clusters were analyzed and the distributional patterns of the detected clusters were assessed using the geometric distribution of the aftershock hypocenters. The spatial and temporal distribution of aftershocks reveals interesting key features of the deep rupture complexity of the Van earthquake. This study presents the results of the first detailed hypocentral observations and this is important data for future seismic hazard analyses in the study area.