Investigation of site effect of Lake Van region (eastern Turkey) by using strong ground motion records

The site effect plays a very important role in determining the structural damage that may occur in a possible major earthquake. In this study, seventy-nine strong ground-motion records (M > 4.5) from past earthquake events in the Lake Van region, recorded by 14 accelerometer stations located on dissimilar geological units, were analyzed for local soil properties using horizontal-to-vertical spectral ratio (EHVSR) method. In addition, EHVSR results were compared with Standard Spectral Ratio (SSR) results, which is another method used to determine soil amplification. The obtained predominant period, amplification factor, seismic vulnerability index (Kg) and bedrock depth values were examined. The EHVSR results show that the predominant frequencies of the sites and the amplification factor values were estimated as 0.58-5.77 Hz and 1.84-7.5, respectively. The seismic vulnerability index (Kg) values, which are crucial parameter in hazard assessment, change from 1.6 to 30. The bedrock depths range between 11 and 186 m for the study area. From the results of this study it is found that the damage may be high after a possible destructive earthquake in the study area where the predominant period, amplification, Kg values and bedrock depth are high.