Design and Development of a Gis-based Seismotectonic Source Model for Iran

Iran is located in a seismically active region and exposed to seismic activity from many seismic sources and active faults. Probabilistic seismic hazard assessment is the basis for many pre and postearthquake risk management issues. Definition and parameterization of active faults and seismic sources are among the most important aspect for reliable PSHA studies. In this paper an effort in designing and development of a GIS-based database representing active faults and seismic sources zones is presented. A GIS-based database has been conducted which provides facility to update and complete information from latest researches. It facilitates efficient organization of faults characteristics such as strike, dip angle, fault length, fault mechanism, horizontal and vertical slip rates and includes all publically available researches on seismotectonic and active faults of Iran. The database also contains information on historical earthquakes, field observations and photographic images, satellite images, geo-referenced images and published articles for all known faults within Iranian territory. The GIS-based system used to conduct this database provides facility for various visualization of geographical and attributes information. In this study also two alternative seismic source models with their seismotectonic parameters are proposed. The geological and tectonic maps of Iran, maps showing smoothed frequency of earthquakes; fault orientations and cumulative distribution of seismic moment have been prepared and used as tools to determine the boundaries of these two seismotectonic models. The seismicity parameters such as a-value, b-value and maximum magnitude are determined for each seismotectonic provinces.