Using 48016 synthetic maximum Wood-Anderson amplitudes read from waveforms of 2650 events recorded by Iranian permanent national networks and temporary seismic networks belong to Institute for Advanced Studies in Basic Sciences, the empirical attenuation curve for local magnitude of Iran has been calculated as follow,

where R is hypocentral distance in km and is maximum displacement amplitude of shear wave in millimeter. This formula is valid for hypocentral distances between 10 and 800 km. We have used the relocated earthquakes with location uncertainties of 5 km or less. The high accuracy of events location and the near-station records enabled us to estimate the geometrical spreading with higher accuracy. The calculated attenuation curve shows a larger geometrical spreading for hypocentral distances closer than 100 km, representing a super-spherical geometrical spreading, and a smaller value for intrinsic attenuation for distances farther than 200 km once compared with the currently used ML relationship of Hutton and Boore (1987).