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 The moment magnitude scale (MMS; denoted explicitly with or Mwg, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. was defined in a 1979 paper ...

, and had a

surface-wave magnitude The surface wave magnitude (M_s) scale is one of the magnitude scales used in seismology to describe the size of an earthquake. It is based on measurements of Rayleigh surface waves that travel along the uppermost layers of the Earth. This mag ...

of 6.7. The shock had a maximum Mercalli intensity of VIII (''Severe''). Many villages were devastated and financial losses amounted to $5 million (in 1981 USD). Despite the sparsity of the area, 3,000 were injured and 1,400 were killed.

Tectonic setting

Eastern Iran Eastern Iran includes the provinces North Khorasan, Razavi Khorasan, South Khorasan and Sistan and Baluchestan some of which share a border with Afghanistan and Pakistan. Some references also count Kerman Province to this region. Dominated by des ...

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 The Lut Desert, widely referred to as Dasht-e Lut (, "Emptiness Plain"), is a salt desert located in the provinces of Kerman and Sistan-Baluchestan, Iran. It is the world's 33rd-largest desert, and was included in UNESCO's World Heritage List ...

Kerman Province Kerman province () is the largest of the 31 provinces of Iran. Its capital is the city of Kerman. The province is in the southeast of Iran. In 2014 it was placed in Region 5. Mentioned in ancient times as the Achaemenid satrapy of Carma ...

, 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 Strike may refer to: People *Strike (surname) * Hobart Huson, author of several drug related books Physical confrontation or removal *Strike (attack), attack with an inanimate object or a part of the human body intended to cause harm * Airstrike, ...

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 (Sarvestan segment) 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 The Modified Mercalli intensity scale (MM, MMI, or MCS) measures the effects of an earthquake at a given location. This is in contrast with the seismic magnitude usually reported for an earthquake. Magnitude scales measure the inherent force or ...

of VIII (''Severe''). 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

fissure A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes. Ground fissure A ...

d 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 Bar or BAR may refer to: Food and drink * Bar (establishment), selling alcoholic beverages * Candy bar ** Chocolate bar * Protein bar Science and technology * Bar (river morphology), a deposit of sediment * Bar (tropical cyclone), a laye ...

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 (in 1981 dollars).

Notes

References

Sources * * * * * * *

External links

* {{Earthquakes in Iran 1981 earthquakes Earthquakes in Iran 1981 in Iran History of Kerman province June 1981 in Asia