[S07-3] Hazard and risk assessment II

[S07-3-02] A Novel Geodetic-based Probabilistic Seismic Hazard Model for Iran

^○Alireza Lotfi¹, Hamid Zafarani², Alireza Khodaverdian³ (1.PhD student of International Institute of Earthquake Engineering and Seismology, Tehran, Iran, 2.Associate Professor of International Institute of Earthquake Engineering and Seismology, Tehran, Iran, 3.PhD of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran)

This study develops a preliminary probabilistic seismic hazard (PSHA) model for Iran using seismic moment rates obtained through combined analysis and modeling of Iranian seismic, geodetic, and geologic data. PSHA has previously been based on the extrapolation of the large earthquakes frequency from rates of small ones that recorded instrumentally in 50 – 100 year-long earthquake catalogs. Unfortunately, factors such as incomplete catalogs, long term return period of large and strong earthquakes and short term catalog give not reliable results. Therefore the hazard analysis that is based on inputs which leads to less uncertainty is necessary. For some place in the world such as California, Canada, Japan, New Zealand and Italy, geodetic and geological data is used in hazard analysis by researchers. The results show that estimated earthquake rates are larger than those derived from earthquake catalogs. In this regard, using novel and alternative approaches in hazard assessment will greatly improve our knowledge and many questions about spatial-temporal distribution of earthquakes could be answered. Moreover, the ground motion parameters uncertainty as hazard analysis output will be reduced. In a recent study (Khodaverdian et al. 2015) the long-term deformation of the Iranian Plateau is estimated by the Neokinema software using updated Iranian database including latest fault traces, geologic fault offset rates, GPS velocities, principal stress directions, and velocity boundary conditions. Accordingly in this study, for the first time an independent hazard estimate for the Iranian Plateau will be obtained through the seismic moment rate required to accommodate current rates of deformation from geodetic and geological data. The estimations could be compared with the results of traditional seismic-based hazard analysis. The final outcomes are time-dependent and time-independent probabilistic seismic hazard models.