Site characterization in the Van settlement (Eastern Turkey) using surface waves and HVSR microtremor methods

Abstract

The settlements around Lake Van are generally located on young, unconsolidated, saturated, Quaternary aged, current lake and stream sediments. The region is under active tectonism, and many destructive earthquakes have occurred in the area both recently and in historical times. The site effect plays a very crucial role in the prediction of earthquake damage to existing structures and in the planning and design of new structures. The main purpose of this study is to determine the mechanical and physical properties of soils in and around the settlement area of Van and to determine their behaviour under a possible earthquake. Considering these situations, both borehole-based geological data and data obtained from geophysical methods were collected in the Van settlement area.Within the scope of this study, 247 boreholes (the maximum drilled depth approximately 5 km), 185 shallow seismic profiles, 56 multi-channel analysis of surface wave (MASW) profiles, and more than 200 single-station microtremor measurements were collected in the study region, and the soil structure of the study area was evaluated and mapped by analysing the data obtained. In order to investigate the engineering properties of the study area, the parameters such as shear-wave velocity (Vs) at each layer, average Vs down to 30 m depth (Vs30), soil classification, fundamental frequency (period) and the ground motion amplification factor, have been prepared. All of the geological and geophysical data sets obtained in the study area within the scope of this study were mapped with GIS-based database features, and an updatable database was prepared for future works.