1981 Golbaf earthquake
The 1981 Golbaf earthquake struck the Iranian desert by the village of Golbaf on June 11 at. The shock measured 6.6 on the moment magnitude scale, and had a surface-wave magnitude of 6.7. The shock had a maximum Mercalli intensity of VIII. Many villages were devastated and financial losses amounted to $5 million. Despite the sparsity of the area, 3,000 were killed and 1,400 were killed.
Tectonic setting
Eastern Iran is moving at a rate of approximately /yr with respect to Afghanistan. To accommodate this, the north-south trending Sabzevaran-Gowk-Nayband fault system began to develop in the western margin of the Dasht-e Lut.
The Gowk fault is a north-northwest trending fault that extends for over across the Lut Desert in Kerman Province, Iran. The fault moves dextrally and reverse, and has slipped at a rate of around /yr for the past 6-8 kyr. With a strike of 155 degrees, the Gowk fault does not orient itself parallel with the slip in the region. As a result, the Shahdad Thrust system takes up the shortening component of regional slip. The Gowk fault is very active, generating multiple other destructive earthquakes such as the 1981 Sirch earthquake. Despite this activity, a ~ segment in the south of the fault has remain unbroken, leading to a high potential hazard for future earthquakes.
Earthquake
The, shock struck near the village of Golbaf at. The earthquake had a maximum Modified Mercalli intensity of VIII. The complex rupture extended across at least of the Gowk fault system. An eastern segment slipped dextrally and vertically over a span. A western segment had little offset over a rupture, but fissured along its length. These surficial displacements are far smaller than would be expected for an earthquake of this size, but this can be explained by the depth of the earthquake. Average slip at depth was estimated to be. The earthquake led to a static stress increase of 3.4 bar on the southern Sarvestan segment of the Gowk fault. Additionally, an increase of up to 2 bars to the north helped trigger the later 1981 Sirch earthquake.
Aftershocks
The earthquake had a few + aftershocks for the next couple weeks, but seismicity was not well recorded by teleseismic observations. A month and a half after the mainshock, on July 28, the 1981 Sirch earthquake struck along the Gowk fault in a similar area. Despite nucleating in the same area, it ruptured in a completely different direction, with the rupture zones having no overlap. It caused further destruction to the already severely damaged villages nearby, though killed much fewer people as the populace was living in tents after the original shock.
Impact
The strong earthquake left 3,000 injured and 1,400 killed. Every village in the Golbaf depression was devastated. Losses were estimated at $5 million USD.