Reconnaissance Report on the Northern Iran Earthquake of June 21, 1990

Keywords: Traditional Housing, Unreinforced Masonry, Damage, Adobe, Buildings, Liquefaction, Masonry Infill, Iran, and Concrete.

Abstract: On June 21, 1990, an earthquake, with an epicenter reported to be approximately 200 km northwest of Tehran, Iran, struck the Gilan Province. The earthquake caused strong shaking in a large part of Iran, including Tehran and Tabriz. It also caused widespread damage in areas within a 100 km radius of the epicenter including the city of Rasht and hundreds of towns and villages in the Gilan and Zanjan provinces. It has been estimated that this earthquake caused between 35,000 and 50,000 fatalities. Most of the fatalities resulted from the collapse of, and major damage to, approximately 100,000 buildings. Poor performance of buildings was due to the use of brittle construction materials, inadequate design and detailing, or deficiency in workmanship with unreinforced masonry buildings being the most hazardous form of building construction. Nonductile concrete frame buildings showed poor performance, while bridges performed relatively well. The 106 meter high Sefidrud Dam, located within 1 km of the epicenter and subjected to very intense ground motion, appeared to sustain little damage. The data for this report is based on the observations of the author during a brief reconnaissance of the area one month after the earthquake, as well as information reported by other sources.