Seismic Hazard Zoning in Iran; A Challenge with Major Seismic Gaps Near Megacities

Seismic hazard zoning maps in Iran have been developed in the last 40 years. The first generations of such maps for Iran were provided based on the deterministic maximum intensity approach in the 1970s.The 1st generation of seismic hazard zoning maps have been developed based on either completion of the historic and instrumental earthquake catalogs or the improvement of seismotectonic studies and active fault setting in Iran. The attenuation relations, developed in northern America were the empirical model for the 1st probabilistic hazard assessment for all over country. The 2nd generation of maps were published in 1984 in terms of PGA hazard zoning map for 475 years return period. Then, the next generation of seismic hazard zoning studies was performed for Dam sites that were under construction during 1980's and 1990's in Iran. The Seismic hazard zoning map of Iran for design earthquake (or so called 475 years of return period), has been constantly prepared as an attachment to the different editions of the Iranian Seismic Building code, meanwhile several other studies have been performed using different updated data and methods. In the last decade, the application of spectral attenuation laws has resulted in the spectral hazard zoning maps. These maps have been developed using region-specific ground-motion prediction equations by considering various ground-motion parameters that involve spectral acceleration, displacement and peak ground-motion values. Developing region-specific tools useful for mapping local site conditions, there are on-going attempts to develop the probabilistic seismic intensity zoning maps for the country. This article will focus on seismic gaps and the challenge to include such gaps specially nearby megacities in Iran. Two major seismic gaps nearby Tehran and Tabriz are discussed in more detail

کلیدواژه ها:

Developing ، Hazard ، Major ، Seismic