Intensity-Magnitude Relationship and Intensity Attenuation Law in Iran

This paper is devoted to explore the relationship between earthquake intensity in the epicenter and its magnitude as well as the intensity attenuation laws of the Iranian earthquakes. For this purpose, available data, reports, seismotectonic and isoseismal maps, related to 21 destructive earthquakes in a period of 1957 to 1998, were studied.The results show that the intensity-magnitude relationships and the intensity attenuation laws are strongly dependent on the site geology that specifies local effects. Therefore, the sites have been classified, according to site geology, into two groups, hard sites and soft sites. The intensity-magnitude and intensity attenuation versus the distance from the earthquake sources (surface refaulting of the causative fault(s)) were determined and introduced for each of the two site groups. Finally, the obtained laws were compared with some other laws offered by other researchers.