Application of Seismic and Resistivity methods to investigate Amiriyeh (Iran) site geology characterization from seismic Micro-zonation point of view

This paper is devoted to compiling a site geology map for town of Amiriyeh, from seismic Macro-zonation point of view using geophysical methods of shallow seismic, down-hole seismic and resistivity surveys. In this map site geology has been classified based on shear wave velocity, according to the criteria for site geology classification offered in the Iranian code of practice for seismic resistant design of buildings. Amiriyeh is a small town with approximately 9000 inhabitants, located in Semnan province, central Iran. In the first step, the town was initially investigated from geological, topographical and facilities aspects for geophysical surveying and some locations were selected for the investigations. In each one of the selected locations, a refraction seismic profile involving 2 or 3 shot points and 24 geophones as well as a vertical electrical resistivity sounding was surveyed. A down-hole seismic survey was also carried out in a few existing wells. The acquiesced data was processed and interpreted and geological layers were identified according to the seismic and resistivity properties. Shear and compressional wave velocities for each layer were estimated. Then velocity maps were compiled for different thicknesses of the soil, (from the surface to various depths). Finally, a site geology Micro-zonation map was compiled for Amiriyeh town. In this map the zones were classified based on the soil (site) classification criteria offered in the Iranian seismic code. According to the obtained results, Amiriyeh is located over soft soils which are involved in groups of IV and III (very close to IV) of the seismic code.