Historic Earthquakes

Northern Iran
1997 May 10 07:57:29 UTC
Magnitude 7.3

Tectonic Summary

This earthquake occurred to the north of the collision zone between the Arabian plate and the Eurasian plate. This region is tectonically very active and is comprised of several microplates. This zone been highly active in historic times, most notably with the Dasht-e Bayaz earthquake (magnitude 7.3) of 1968, which resulted in 12,000-20,000 casualties. The 1968 quake rupture lenght was 80 kilometers. The May 10, 1997 shock occurred on the Abiz fault, according to recent field studies by Manuel berberian and as reported by email.

The sense of faulting for both the 1968 and 1997 quakes was strike-slip (no significant vertical motion). It seems likely that the fault motion of the 1997 quake was left-lateral, like that for the 1968 event (if an observer stands looking to the other side of the fault, left-lateral means that he should see displacement to the left). This type of fault movement may arise from this region being squeezed eastwards, as the Arabian plate pushes northwards into the Zagros Mountains. The Arabian plate is bounded on the north by the Zagros Mountains, on the south by the spreading center at the Red Sea, on the west by the left-lateral, strike-slip fault system that includes the Dead Sea fault, and on the east by the right-lateral, strike-slip Owens fracture zone, which is located beneath the Indian Ocean.

Sources for further reading:

The Dasht-e Bayaz quake of 1968: Entire issue of the October, 1969 Bulletin of the Seismological Society of American is devoted to this earthquake. See especially N. N. Ambraseys and J. S. Tchalenko (1969), The Dasht-e Bayaz (Iran) earthquake of August 31, 1968: A field report, Bulletin of the Seismological Society of America, v. 59, p. 1751-1792.

James Jackson and Dan McKenzie (1984), Active tectonics of the Alpine-Himalayan belt between western Turkey and Pakistan, Geophysical Journal of the Royal Astronomical Society, v. 77, p. 185-264,

N. N. Ambraseys and C. P. Melville, 1982, A history of Persian earthquakes, Cambridge University Press, 219 pp.,

A. A. Nowroozi (1972), Focal mechanism of earthquakes in Persia, Turkey, West Pakistan, and Afghanistan and plate tectonics of the Middle East.

Berberian, M., 1979- Earthquake faulting and bedding thrust associated with the Tabas-e-Golshan (Iran) earthquake of September 16, 178, Bull.Seism.Soc.Am., 69(6), 1861-1887.

Berberian, M., 1981- Active faulting and tectonics of Iran. In: H.K. Gupta and F.M. Delany (eds.), Zagros-Hindu Kush-Himalaya Geodynamic Evolution, Geodynamics Series, Volume 3, 33-69. AM.Geophys.Union.