Abstract
The June 20, 1990, Rudbar-Tarom (NW Persia) earthquake (Ms = 7.7, Mb = 6.4, I = X) was extremely destructive, killing a reported 40,000 people and leaving more than 500,000 people homeless. Three cities (Rudbar, Manjil and Lowshan) were destroyed, together with 700 villages and another 300 villages were slightly damaged in the densely populated area of the western Alborz Mountains, southwest of the Caspian Sea. Evidences of both earthquake faulting and folding were observed in the meizoseismal area. Strong seismic shaking together with a complex soil and rock structure across the steep topography of the high Alborz produced large-scale ground disruptions due to the multitude of soil and rock slides in the mountains, several cracks and fissures, and soil liquefaction in the Sefid Rud delta, at least 60 km to the northeast of the source area. The effects of soil and topography variations involving amplification of waves locally seem to be responsible for the damage pattern.