1981 Golbaf earthquake
Earthquake in Kerman County, Iran
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The 1981 Golbaf earthquake struck the Iranian desert by the village of Golbaf on June 11 at 10:54:25 local time. 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 (Severe). Many villages were devastated and financial losses amounted to $5 million (in 1981 USD). Despite the sparsity of the area, 3,000 were killed and 1,400 were injured.
  Tehran Kerman  | |
| UTC time | 1981-06-11 07:24:25 |
|---|---|
| ISC event | 625020 |
| USGS-ANSS | ComCat |
| Local date | June 11, 1981 |
| Local time | 10:54:25 IRST |
| Magnitude | 6.6 Mw[1] 6.7 Ms[2] |
| Depth | 18 km (11 mi)[1] |
| Epicenter | 29.91°N 57.83°E[1] |
| Type | Strike-slip and reverse[3] |
| Total damage | $5 million[4] |
| Max. intensity | MMI VIII (Severe)[5] |
| Foreshocks | No[3] |
| Casualties | 3,000 dead 1,400 injured[5] |
Tectonic setting
Eastern Iran is moving at a rate of approximately 15 mm (0.59 in)/yr with respect to Afghanistan. To accommodate this, the 600 km (370 mi) north-south trending Sabzevaran-Gowk-Nayband fault system began to develop in the western margin of the Dasht-e Lut.[6][7]
The Gowk fault is a north-northwest trending fault that extends for over 150–180 km (93–112 mi) across the Lut Desert in Kerman Province, Iran.[3][8] The fault moves dextrally and reverse, and has slipped at a rate of around 3.1–5.7 mm (0.12–0.22 in)/yr for the past 6-8 kyr.[i][3][9][10] 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.[11] The Gowk fault is very active, generating multiple other destructive earthquakes such as the 1981 Sirch earthquake.[6] Despite this activity, a ~90–100 km (56–62 mi) segment in the south of the fault (Sarvestan segment) has remain unbroken, leading to a high potential hazard for future earthquakes.[6][9]
Earthquake
The Mw 6.6, Ms 6.7 shock struck near the village of Golbaf at 10:54:25 local time.[1][2] The earthquake had a maximum Modified Mercalli intensity of VIII (Severe).[5] The complex rupture extended across at least 15 km (9.3 mi) of the Gowk fault system.[12] An eastern segment slipped 3 cm (1.2 in) dextrally and 5 cm (2.0 in) vertically over a 14.5 km (9.0 mi) span. A western segment had little offset over a 7.5 km (4.7 mi) rupture, but fissured along its length.[3] 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.[13] Average slip at depth was estimated to be 1.4 m (4 ft 7 in).[14] The earthquake led to a static stress increase of 3.4 bar on the southern Sarvestan segment of the Gowk fault.[15] Additionally, an increase of up to 2 bars to the north helped trigger the later 1981 Sirch earthquake.[16]
Aftershocks
The earthquake had a few mb 4+ aftershocks for the next couple weeks, but seismicity was not well recorded by teleseismic observations.[17] 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.[18] 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.[19]
Impact
See also
Notes
- kyr = thousand years