Earthquake hazard zonation of the Isfahan city, Iran

Abstract

Earthquake hazard zonation is the most important step towards seismic risk assessment and mitigation strategy in densely populated regions. The city of Isfahan, as an important industrial and historical center, is considered among the major economic and cultural poles in Iran. In addition, the existence of seismic evidence and several identified faults emphasizes the need for conducting seismotectonic studies and the development of seismic zonation for this city. In this regard, first, the main faults of the studied area were identified using the digital data from the satellite photos, and their conditions were corroborated by field observations. Then, a probabilistic seismic hazard assessment (PSHA) was conducted using SeisRiskIII software. The first outcome in the current study was preparation of the seismic hazard zoning maps for different hazard levels (according to the Building and construction Iranian Earthquake Code (Std. No. 2800)). Using selected compatible acceleration time histories from past earthquakes, the second was the development of the geotechnical amplification conversion functions corresponding to different soil conditions on bedrock, using SHAKE2000 software, which is based on the application of one-dimensional equivalent linear method (ELM). The results include the distribution maps of average shear wave velocity of the soil, the maximum horizontal acceleration on the ground surface, and the amplification ratio. According to these maps, the PGAs at ground surface and the amplification ratios range between 0.25 g to 0.5 g and 0.9 to 1.9, respectively. © 2014 ejge.