A probabilistic deformation-based seismic hazard model for Iran

Probabilistic seismic hazard analysis, as the most prevalent approach to evaluate earthquake hazard, is commonly based on earthquake catalogs. Although previous studies show that the recurrence time of large-magnitude (M-w > 7.0) events in Iran is more than similar to 1000-2000 years, the available instrumentally recorded earthquakes are limited to less than 100 years. With the idea of having another proxy for seismicity rates, we propose a methodology to evaluate activity rates from strain rates in a combination of regional estimates of beta and m(max). Considering the comprehensive deformation model of the Iranian Plateau, we found that the deformation-based occurrence rates are more than the catalog-based occurrence rates in all seismotectonic provinces in the Iranian Plateau. The ratios of the deformation-based to the catalog-based occurrence rate are between 1.34 and 2.35. For the first time, a probabilistic deformation-based seismic hazard model for the Iranian plateau is also developed and Peak Ground Acceleration (PGA) values for 10% and 2% POEs in 50 years are estimated. The highest levels of PGA are found in the Azerbaijan and Alborz seismotectonic provinces, where the highest value of strain rates is located. For all provinces, except the Zagros region, the spatial averages of PGA with 10% POE in 50 years from the deformation-based model are up to similar to 23% higher than those from a traditional probabilistic seismic hazard.