Seismic, ground motion and geotechnical characteristics of the 2011 Van-Erciş and Van-Edremit earthquakes of Turkey, and assessment of geotechnical damages

Abstract

Two devastating earthquakes with moment magnitudes of 7.2 and 5.6 occurred on October 23, 2011 (Van-Ercis earthquake) and November 9, 2011 (Van-Edremit earthquake), respectively, in the Van Province of the eastern Turkey. The Van-Ercis and Van-Edremit earthquakes caused 604 and 38 fatalities, respectively, and heavy damage to buildings and other structures, particularly in Ercis town and Van City. In this study, characteristics of both main shocks and their geotechnical aspects, such as local site conditions, liquefaction phenomena and associated ground deformations and slope failures are evaluated. The failures of slopes and embankments and rock falls and ground liquefaction may also be indications of diluted ground deformation caused by the earthquake fault. It seems that a wedge-like body bounded by two fault planes was uplifted. As a result of this movement, the northern shoreline of Van Lake uplifted. The November 9, 2011 Van-Edremit earthquake was triggered due to the variation of crustal stresses induced by the October 23, 2011 earthquake. The effects of local site conditions have contributed to the damage of some parts of Ercis city and its vicinity; however, the ground liquefaction was not observed in the city as anticipated. With a magnitude of 5.6, the Van-Edremit earthquake is probably the smallest magnitude earthquake to cause liquefaction in Turkey so far.