Poster of the Western Iran Earthquake of 31 March 2006 - Magnitude 6.1

Tectonic Summary

Iran lies in the wide boundary that separates the Arabia and Eurasia plates. This earthquake occurred as the result of stresses generated by the motion of the Arabian plate northward against the Eurasian plate at a rate of 2 to 3 cm/year (about one inch per year). Deformation of the Earth's crust in response to the plate motion takes place in a broad zone that spans the entire width of Iran and extends into Turkmenistan. Earthquakes occur primarily as the result of reverse faulting and strike-slip faulting within the zone of deformation. The March 31 earthquake occurred close to the Main Recent Fault, a major strike-slip fault, but we do not know at present if the earthquake occurred on that fault or on a related smaller fault. The section of the Main Recent Fault near the epicenter of the March 31 earthquake produced a magnitude 7.4 earthquake in 1909.

Earthquake History

Several severe earthquakes have occurred near this recent Iranian event. The most deadly was a magnitude 7.4 earth- quake that struck on June 20, 1990, located about 175 km to the WNW of this recent event. This earthquake killed an estimated 40,000 to 50,000 people, injured more than 60,000, and left 400,000 or more homeless. There was extensive damage and landslides in the Rasht-Qazvin-Zanjan area and nearly all buildings in the Rudbar-Manjil area were destroyed. Another nearby devastating quake struck on September 1, 1962. This magnitude 7.3 quake killed about 12,000 people. More distant recent events include a February 28, 1997 magnitude 6.1 earthquake occurring about 300 km to the north (near the Armenia-Azerbaijan-Iran border), and a May 10, 1997 magnitude 7.3 event occurring about 1000 km to the east. The February 28th earthquake killed at least 1,100 people, injured 2,600, and left 36,000 homeless. The May 10th earth- quake killed at least 1,567 people, injured 2,300, and left about 50,000 homeless. The Dec 26, 2003, Bam, Iran, earthquake killed over 30,000 people, injured over 30,000, and destroyed over 85 per cent of all buildings and infrastructure.

Other deadly earthquakes occurring in Iran include: