Macroseismic Intensity and Attenuation laws: A Study on the Intensities of the Iranian Earthquakes of 1975-2000

The earthquake intensities in Iran are reported from the inhabitant regions. A catalog for the recent earthquakes since 1975 until 2000 is prepared. The macroseismic intensity investigations in Iran are carried out after the great and moderate earthquakes (usually after the destructive events). The intensity reports for the recent Iranian earthquakes with an acceptable level of confidence are selected to form the catalogue of the intensity values of recent earthquakes in Iran. This catalog comprises the 470 intensity values for which the information for the localities of reported or estimated intensity values and the earthquake source specifications could be found. The uncertainty of the intensity estimations are found to be +/- one degree of intensity. The attenuation of the earthquake intensities in Iran is presented as well using the developed catalogue and the coefficients are presented in this article. The attenuation rate for different regions of Iran coincides well with the attenuation of strong motion accelerations using the Iranian data coming from the same period of time (1975-2000).