A systematic geophysical approach for site response of the dinar region, southwestern turkey

On 1 October 1995, the Dinar earthquake (Mw 6.1) devastated the city of Dinar in southwestern Turkey. We investigated the effects of geological conditions on the localized damage patterns using microtremor survey and multichannel analysis of surface waves. The microtremor survey was carried out in and around the Dinar basin to determine the resonance frequencies and depths of the sedimentary layer at 38 different locations using a broadband seismometer. The shear-wave velocity profile of the basin sediments was estimated from the inversion of the microtremor horizontal-to-vertical spectrum based on surface waves from seismic noise at each site using a genetic algorithm. The average shear-wave velocities estimated from the multichannel analysis of surface waves experiments were given as constraints in the inversion. A new relationship between the thickness of basin sediment and the main peak frequency in the horizontal-to-vertical spectral ratios was derived. This relationship allows a zonation of the Dinar region, which is consistent with previous studies and can be importantly used for the seismic hazard evaluation of the region