Earthquake Hazard Zoning in Borujerd County with an Emphasis on Urban Development

In this study, the study region is Zagros orogenic belt in the southwest of Iran and it is situated in the structural zones called Sanandaj-Sirjan (the northeastern half of the region) and crushed Zagros (southwestern half of the region). In this study, the basic Guttenberg-Richter method as well as the updated Kiko-Selovel method have been used and the Kiko-Selovel method is based on the double bounded Guttenberg-Richter distribution function so that the importance of applying novel methods can be more clarified through the comparison of the results. In order to investigate the depth phase of the earthquakes in the studied domain, the data obtained from the earthquakes’ epicentral mechanism was utilized. To do so, the focal data of the studied region’s design level earthquake mechanisms were extracted within a 200-kilometer distance from such credible websites as USGS, NEIC, and CMT and the form of their epicentral mechanism was drawn using WInTensor Software and based on the obtained results, the maximum seismic power of the intended faults ranges from 5.8 to 7.8 in the Richter scale. Moreover, the highest seismic powers were found respectively pertaining to Main Zagros’s thrust fault (M=7.8), high Zagros (M=7.6), Kushk Nosrat (M=7.5), Lahbari 9M=7.5), F3 (M=7.4), Zardkuh (M=7.2) and Ardal (M=7.4). The largest horizontal accelerations obtained in the deterministic approach are 0.23g, 0.18g, and 0.17g, respectively. Furthermore, the largest horizontal and orthogonal accelerations in the probabilistic approach and the DBE design level are 0.30g and 0.14g, respectively