The

Lenin Peak Lenin Peak or Ibn Sina (Avicenna) Peak (, ; ; , renamed () in July 2006
(Tajik); for Russian tex
avalanche An avalanche is a rapid flow of snow down a Grade (slope), slope, such as a hill or mountain. Avalanches can be triggered spontaneously, by factors such as increased precipitation or snowpack weakening, or by external means such as humans, othe ...

on the 7,134-meter-high mountain peak in northeast Tajikistan and Kyrgyzstan (then part of the

USSR The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

). The deadly avalanche was triggered by a

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 ...

6.4 earthquake which struck at a depth of 216.8 km beneath the

Hindu Kush The Hindu Kush is an mountain range in Central Asia, Central and South Asia to the west of the Himalayas. It stretches from central and eastern Afghanistan into northwestern Pakistan and far southeastern Tajikistan. The range forms the wester ...

mountains in neighbouring Afghanistan. The incident is believed to be the deadliest mountaineering disaster in history.

Background

The ongoing continental collision between the

Indian Plate The Indian plate (or India plate) is or was a minor tectonic plate straddling the equator in the Eastern Hemisphere. Originally a part of the ancient continent of Gondwana, the Indian plate broke away from the other fragments of Gondwana an ...

and Eurasian Plate results in

tectonic uplift Tectonic uplift is the orogeny, geologic uplift of Earth#Surface, Earth's surface that is attributed to plate tectonics. While Isostasy, isostatic response is important, an increase in the mean elevation of a region can only occur in response to ...

, forming the

Himalaya The Himalayas, or Himalaya ( ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the Earth's highest peaks, including the highest, Mount Everest. More than 100 pea ...

, Hindu Kush, and

Pamir Mountains The Pamir Mountains are a Mountain range, range of mountains between Central Asia and South Asia. They are located at a junction with other notable mountains, namely the Tian Shan, Karakoram, Kunlun Mountains, Kunlun, Hindu Kush and the Himalaya ...

. The two plates collide along a

convergent plate boundary A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a ...

which includes the

Main Himalayan Thrust The Main Himalayan Thrust (MHT) is a décollement under the Himalaya Range. This thrust fault follows a northwest-southeast strike, reminiscent of an arc, and gently dips about 10 degrees towards the north, beneath the region. It is the large ...

. Broad crustal deformation caused by the Indian Plate ploughing into Eurasia causes uplift within the interior of Asia. This action created the

Tibetan Plateau The Tibetan Plateau, also known as the Qinghai–Tibet Plateau or Qingzang Plateau, is a vast elevated plateau located at the intersection of Central Asia, Central, South Asia, South, and East Asia. Geographically, it is located to the north of H ...

. 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 Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that ...

, or

strike-slip faulting In geology, a fault is a Fracture (geology), planar fracture or discontinuity in a volume of Rock (geology), rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust (geology ...

. 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. 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 In plate tectonics, slab detachment or slab break-off may occur during continent-continent or arc-continent collisions. When the continental margin of the subducting plate reaches the oceanic trench of the subduction zone, the more buoyant contin ...

. This action results in stress accommodation along faults that produces earthquakes when ruptured.

Avalanche

At the time of the quake, 45

mountaineers Mountaineering, mountain climbing, or alpinism is a set of outdoor activities that involves ascending mountains. Mountaineering-related activities include traditional outdoor climbing, skiing, and traversing via ferratas that have become sports ...

were at Camp II, at an elevation of 5,300 meters on the Razdelnaya Route to summit the peak. The team consisted of 23 members of the

Leningrad Saint Petersburg, formerly known as Petrograd and later Leningrad, is the List of cities and towns in Russia by population, second-largest city in Russia after Moscow. It is situated on the Neva, River Neva, at the head of the Gulf of Finland ...

Mountaineering Club, six from

Czechoslovakia Czechoslovakia ( ; Czech language, Czech and , ''Česko-Slovensko'') was a landlocked country in Central Europe, created in 1918, when it declared its independence from Austria-Hungary. In 1938, after the Munich Agreement, the Sudetenland beca ...

, four

Israel Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...

is, two

Swiss Swiss most commonly refers to: * the adjectival form of Switzerland * Swiss people Swiss may also refer to: Places * Swiss, Missouri * Swiss, North Carolina * Swiss, West Virginia * Swiss, Wisconsin Other uses * Swiss Café, an old café located ...

, and a Spaniard. Many of the Soviet fatalities originated from the Russian city of Leningrad, as Saint Petersburg was known during Soviet times. The earthquake caused light shaking, assigned IV on the

Mercalli intensity scale 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 ...

, but was significant enough to cause a block of

serac A serac () (from Swiss French ''sérac'') is a block or column of glacial ice, often formed by intersecting crevasses on a glacier. Commonly house-sized or larger, they are dangerous to mountaineers, since they may topple with little warning. ...

to detach and tumble down

that crashed onto the camp, killing 43 of the 45 climbers. The two survivors, Alexei Koren and Miroslav Brozman, suffered a broken arm and leg. According to them, some team members were still conscious after the avalanche buried them, but rescue attempts failed when the debris hardened into glacier ice. Survivors and witnesses on the mountain did not report any shaking from the earthquake, presumably because the ice acted like a shock absorber. The disaster is the worst in the history of mountaineering, alongside the

2014 Nepal snowstorm disaster The 2014 Nepal snowstorm disaster occurred in central Nepal on 14 October 2014 and resulted in the deaths of at least 43 people of various nationalities, including at least 21 trekkers. Injuries and fatalities resulted from unusually severe snows ...

. The death toll from the incident surpassed that of another event in 1974. Only one body was recovered. In 2008, the glacier ice began to melt, exposing human remains of the expedition.

References

{{Authority control Earthquakes in Afghanistan Earthquakes in Tajikistan Earthquakes in Kyrgyzstan Deaths in avalanches 1990 earthquakes Mountaineering disasters 1990 in Afghanistan 1990 in the Kirghiz Soviet Socialist Republic 1990 in Tajikistan Pamir Mountains 1990 in Russian sport 1990 in the Soviet Union Earthquakes in the Soviet Union 1990 disasters in the Soviet Union 1990 disasters in Afghanistan 1990 disasters in Asia Mountaineering in the Soviet Union July 1990 in Asia

Background

Avalanche

See also

References