Relationships between Modified Mercalli Intensity and Engineering Ground-Motion of the Earthquakes in Persia

New empirical relationships between modified Mercalli intensity (MMI) and engineering ground acceleration (PGA) of the earthquakes were generated for the Iranian territory. MMI and PGA values were gathered from 16 large earthquakes. We derived two sets of relationships which predict MMI in terms of PGA; each developed using both horizontal and three components of accelerograms. The first set is independent of earthquake magnitude and epicentral distance. Better results were observed when magnitude and epicentral distance conditions were included into equations. They might be used for both rapid assessments of ground shaking and also mapping damage potential in Iran and neighboring area.