In Search of the Predecessors of the 2011 Van (Turkey) earthquake

Abstract

[The Mw 7.2 earthquake of 23 October 2011 struck an area of Eastern Anatolia with a long historical record and a long earthquake history. The earthquake occurred in a region of rather complex tectonics resulting from the collision of the Arabian and Eurasian continental plates. The 23 October 2011 earthquake caused heavy damage to Van and several towns and villages around Lake Van, in the districts of Van and Ercis. It was followed by several aftershocks and another strong event (Mw 5.7) that occurred on 9 November 2011, causing further damage and casualties. Though the seismicity of the area is described by some regional parametric earthquake catalogs and has been the subject of several studies, no earthquake with a magnitude equivalent to the 2011 one is reported by the catalog in the area of the 2011 earthquake; so, apparently, there are no predecessors of this earthquake. However, two questions arise: a) could some events located close to Van have been underestimated or mislocated, as frequently happens with poorly known events?, and b) are there gaps in the earthquake history of the Van region? As for the first question, we have not found earthquakes which could, in principle, be underestimated and/or mislocated by the catalog and that could be re-located in the area of the October 2011 earthquake with a comparable magnitude. The earthquake history shows gaps between 1275 and 1646, and later between 1715 and 1834, gaps which have further investigated on the occasion of the preparation of this paper. In conclusion, nothing can be said about earthquakes in the time-window before 1646 in the region east of Lake Van. After that year, no prominent candidate earthquake appears as a possible twin of the 23 October 2011 event.]