Seismic Hazard Zoning in Iran: A State-of-the-Art on the Studies during Four Decades

This is a state-of-the-art paper on the seismic hazard zoning studies performed in Iran since the mid-1970s to 2015. Reliable seismic hazard studies depend on having a robust earthquake catalog, good knowledge of tectonic conditions and relevant attenuation models applied for the hazard calculations. The better input for hazard analysis results in the more reliable parameters and seismic hazard assessments. The first generations of seismic hazard zoning maps in Iran were developed based on the deterministic approaches for calculation of maximum intensities (e.g. [1] and [2]). In 1982, Bozorgnia and Mohajer-Ashjai [3] published the first comprehensive probabilistic hazard assessment for major cities of Iran. The first PGAzoningmap for the greater Tehran region was also published by Berberian et al. [4]. The next generations of seismic hazard zoning studies were carried out for dam sites, which were under construction during the 1980s and 1990s in Iran. A seismic hazard zoning map of Iran for the "design earthquake" (so called 475 years of return period), was published in 1999 as an attachment to the Iranian seismic code for buildings (Standard No. 2800). In the recent years, a number of detailed hazard zoning maps for the greater cities and specific industrial sites have also been presented. The defined spectral attenuation equations for Iran (e.g. [5-17]) can be used for producing spectral zoning maps. These maps can be developed using region specific ground-motion prediction equations by considering various ground-motion parameters that involve spectral acceleration, displacement and peak groundmotion values. Therefore, there are still ongoing attempts to develop the probabilistic seismic zoning maps for Iran. In this paper, the seismic hazard zoningmaps of Iran developed in the last 40 years are investigated. It is tried to depict the development history of the seismic hazard zoning studies for Iran, which have been started since the mid-1970s. Briefly, the trend of such studies was started by the application of deterministic approaches for estimation of intensity and then was continued using probabilistic approaches. Future studies on the seismic hazard zoning in Iran seems to cover newapproaches such as the realistic acceleration and the neo-deterministic approaches, time-dependent mapping, intelligent updating of hazard maps as well as the development of site-specific hazard analysis based on the development of more detailed data.