Grid Source Event-Based Seismic Hazard Assessment of Iran

Abstract

In classical probabilistic seismic hazard analysis method, some basic assumptions are considered in modeling seismic sources. This is done to simplify the procedure and also to handle the lack of information. Many methods assume the homogeneity in the location of future earthquake events within the seismic sources. But some newer researches propose the method of Monte-Carlo simulation for determining the location of future earthquake events based on the observed data as presented in the earthquake catalogues. Another source of uncertainty is raised from assuming that the relative seismicity of different magnitude bins is uniform all over the defined sources, especially for area sources. Dividing the entire country into a few large seismotectonic provinces and the delineation of these major seismotectonic provinces as area sources has been widely used in classical seismic hazard assessment. To determine such provinces, geological, geophysical and tectonic data are required as well as observed earthquake data. The knowledge in these areas is limited and full of uncertainty. This study introduces the grid source event-based method to alleviate the mentioned problem with modeling the spatial pattern of seismicity more faithfully. Iran is chosen as a case study to evaluate the method utilizing 117 years of instrumental recorded earthquake data. The PGA values evaluated in the current study are generally lower than the results of previous studies except for some few spots due to crossing the historical events out and also lesser smoothed seismicity distribution.