New Intensity Prediction Equation for Iran

Abstract

New intensity prediction equation is evaluated for Iran using isoseismal maps of 31 earthquakes with MW 5.1–7.4 occurred from 1939 to 2017 including 7.3 destructive Sarpol-e Zahab earthquake on 12 November 2017. The obtained intensity prediction equation based on Modified Mercalli Intensity (MMI) scale for intensity range 4 to10 and distances less than 150 km is as follows: I = − 0.841 + 1.583 Mw − 1.344 ln$$ \sqrt{R_{epi}^2+{h}^2} $$ − 0.0027$$ \sqrt{R_{epi}^2+{h}^2} $$, where MW is the moment magnitude, Repi is the epicentral distance, and h is the hypocentral depth. The results show different distance-dependent intensity attenuation rate in comparison with previous studies for Iran and other regions of the world. The comparison of the obtained equation with other studies indicate differences that most probably originate from input data consisting of various earthquakes located at different seismotectonic regions in addition to different kind of construction and damage styles in the area under study which have been applied to assign the MMI values. This supports development of region-specific attenuation relationships for more accurate estimation of strong ground-shaking maps, which represent a useful tool for hazard and risk assessment.