An applicable modified probabilistic method for seismic hazard assessment in Northen Khorasan province, Iran

Iran plateau is a vast pressured region along mountain building belt of Alps-Himalayas. North Khorasan province where is studied in this research is located in Kope Dagh seismotectonic province. Kope Dagh seismotectonic province is a mountainous region which final phases of Alps have played a basic role in its present-day formation. This province is an active seismic region with mostly shallow earthquakes with less than 30 kilometers depth. Seismicity of the region indicates high activity in Northen Khorasan and Kope Dagh plate in the area of 56 degrees to 59.30 degrees E and 36 degrees to 38 degrees N. Regarding to the high seismicity and importance of Kope Dagh region because of the existence of Mozduran gas reservoir, which after refinement and desulphurization supplies fuel of Shirvan and Bojnourd cities, and due to economic and cultural importance, it is crucial to analyze seismic hazard in this region. It is important to note that however lots of studies have been done in north -east of Iran, but building codes modification needs more precisely seismic hazard analysis. Furthermore, previous studies have been applied free download softwares, which were provided before 2000, but the most important advantage of this study is applying professional industrial software, which has been written in 2009. This applied software can cover previous software weak points very well such as gridding potential sources, attention to the seismogenic zone and applying attenuation relationships directly. In the present study, modified probabilistic method has been applied instead of traditional one. For this purpose at first, a complete seismic catalogue of main earthquakes of the region provided. Then, map of potential sources prepare and compared to the previous studies. Finally, seismic parameters of the region have been determined for seismic hazard analysis. This study states the most PGA will be experienced in a northwest-central trend, which fits very well with Quchan-Robat and Esfarayen-Robatqarebil faults and matches with the expected trend based on tectonic evidences and previous statistical studies. In this research peak ground acceleration (PGA) will be experienced up to 0.07 gal during the expected earthquake with 63% probability of occurrence in 50 years in the area of Robatqarebil. [Arsham Gheirati, Katayoun Behzadafshar and Arash Motasharreie. An applicable modified probabilistic method for seismic hazard assessment in Northen Khorasan province, Iran. Life Sci J 2012;9(4):2406-2412] (ISSN:1097-8135). http://www.lifesciencesite.com. 357