Lenin Peak disaster
From Wikipedia, the free encyclopedia
 A memorial plaque near Lenin Peak commemorating the victims of the disaster | |
| UTC time | 1990-07-13 14:20:43 |
|---|---|
| ISC event | 362596 |
| USGS-ANSS | ComCat |
| Local date | July 13, 1990 |
| Local time | 18:50:43 AFT |
| Magnitude | Mw 6.4 [1] |
| Depth | 216.8 km |
| Epicenter | 36°22′19″N 70°44′17″E / 36.372°N 70.738°E |
| Max. intensity | MMI IV (Light)[2] |
| Casualties | 43 dead, 2 injured[3] |
The Lenin Peak disaster occurred on 13 July 1990 when 43 climbers were killed during an avalanche on the 7,134-meter-high mountain peak in northeast Tajikistan and Kyrgyzstan (then part of the USSR). The deadly avalanche was triggered by a moment magnitude scale 6.4 earthquake which struck at a depth of 216.8 km beneath the Hindu Kush mountains in neighbouring Afghanistan.[1] The incident is believed to be the deadliest mountaineering disaster in history.
The ongoing continental collision between the Indian Plate and Eurasian Plate results in tectonic uplift, forming the Himalaya, Hindu Kush, and Pamir Mountains. The two plates collide along a convergent plate boundary which includes the Main Himalayan Thrust. Broad crustal deformation caused by the Indian Plate ploughing into Eurasia causes uplift within the interior of Asia. This action created the Tibetan Plateau. Shallow earthquakes occur on faults that accommodate the tectonic stresses caused by the collision. Some of the largest earthquakes have exceeded magnitude 8.0, while even moderately large 6.0 events have resulted in thousands of fatalities. Most of these earthquakes are associated with reverse, thrust, or strike-slip faulting.
The earthquake on 13 July did not originate from within a shallow fault; rather it struck at a depth of 216.8 km beneath the surface; far too deep for a shallow crustal source. Where the earthquake occurred, is an "earthquake nest"; an area of high seismicity in a particularly small region. Large earthquakes with magnitudes of up to 7.5 have occurred in the same concentrated region with an average recurrence interval of 15 years. These earthquakes correspond to reverse faulting at a depth of 170 to 280 km.[4] These earthquakes rather than occurring at a plate boundary, are sourced from within the Indian Plate as it dives beneath the Hindu Kush. As the tectonic slab of the Indian Plate descends at a near-vertical angle into the mantle, it stretches and begins to "tear", eventually leading to a slab detachment.[5] This action results in stress accommodation along faults that produces earthquakes when ruptured.