Evaluation of relationship between local site conditions and earthquake damage: After 2011 Van earthquakes

Two devastating earthquakes occurred on 23rd October and 9th November in 2011 with moment magnitudes of Mw=7,2 and Mw=5,6, respectively. Because of the both earthquakes, 644 people lost their lives, 1966 people were injured and 17005 buildings were damaged. One of the most important factors on structure damage was the local site conditions. So, clarifying changes in local site conditions and lessening the damages that will probably happen have a great value for Van City which has a high risk of earthquake. Standard Penetration Tests (SPT) was collected data from 82 different points in residential locations. From these drills, 81 of which are in suitable depth were evaluated and their characteristics was investigated as mean shear wave velocity of uppermost 30 m (Vs(30)) and Vs(30)-depth maps were formed. Using this approach, soil classification maps were generated according to the National Earthquake Hazard Reduction Program (NEHRP 2003). The soil classification maps were compared with the damage distribution data after the earthquake occurred. It was noticed that observations acquired in the most damaged regions and the least damaged regions were same. As a result, it was realized that the damage density is not only the result of the soil properties, but also quality of the structures.