![Usoi Sarez](https://upload.wikimedia.org/wikipedia/commons/6/6c/Usoi_Sarez.png)
The Usoi Dam is a natural
landslide dam
A landslide dam or barrier lake is the natural damming of a river by some kind of landslide, such as a debris flow, rock avalanche or volcanic eruption. If the damming landslide is caused by an earthquake, it may also be called a quake lake. Some ...
along the
Murghab River
The Marghab River (Persian/Pashto: مرغاب, ''Morqâb''), anciently the Margiana (Ancient Greek: Μαργιανή, ''Margianḗ''), is an long river in Central Asia. It rises in the Paropamisus Mountains (''Selseleh-ye Safīd Kūh'') in Ghor ...
in
Tajikistan
Tajikistan (, ; tg, Тоҷикистон, Tojikiston; russian: Таджикистан, Tadzhikistan), officially the Republic of Tajikistan ( tg, Ҷумҳурии Тоҷикистон, Jumhurii Tojikiston), is a landlocked country in Centr ...
. At high, it is the tallest dam in the world, either natural or man-made. The dam was created on February 18, 1911, when the 7.4-
Ms Sarez earthquake caused a massive
landslide
Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated grade (slope), slope failures, mudflows, and debris flows. Landslides occur in a variety of ...
that blocked the flow of the river.
The dam is formed of approximately of rock dislodged from the steeply sloped river valley of the
Murghab, which cuts from east to west through the high and rough
Pamir Mountains
The Pamir Mountains are a mountain range between Central Asia and Pakistan. It is located at a junction with other notable mountains, namely the Tian Shan, Karakoram, Kunlun, Hindu Kush and the Himalaya mountain ranges. They are among the world ...
. It is named after the village of Usoi, which was completely buried by the 1911 landslide. The dam rises to a height of from the original valley floor.
The basin formed by Usoi Dam now holds
Sarez Lake
Sarez Lake (russian: Сарезское озеро; tg, Сарез кӯл, Sarez Kūl) is a lake in Rushon District of Gorno-Badakhshan province, Tajikistan. Length about , depth few hundred meters, water surface elevation about above sea leve ...
, a -long lake holding of water. Water does not flow over the top of the dam, which would quickly cause it to erode away; instead, water seeps out of the base of the dam at a rate which approximately matches the rate of inflow, maintaining the lake at a relatively constant level. The flow averages about 45 cubic meters per second, and dissipates about 250 megawatts.
Geologists are concerned that the Usoi Dam may become unstable during future large-magnitude earthquakes, which are relatively common in the seismically active Pamirs, and might collapse due to
liquefaction
In materials science, liquefaction is a process that generates a liquid from a solid or a gas or that generates a non-liquid phase which behaves in accordance with fluid dynamics.
It occurs both naturally and artificially. As an example of the ...
or subsequent landslides during such an event. Collapse of the dam would unleash a locally catastrophic flood. The Murghab's river valley tends to be relatively narrow and steep. This would focus and maintain any flood's destructive power as it swept through the valley of the
Murghob District
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The dam wall survived a localised 7.2 magnitude earthquake, the
2015 Tajikistan earthquake
On December 7, 2015, an earthquake measuring 7.2 on the moment magnitude scale struck Tajikistan west of Murghab at 07:50 UTC at a depth of . The earthquake was also felt in neighboring Xinjiang in China, India, Afghanistan, Pakistan and Kyrgyz ...
, on the 7th December 2015 with no visible signs of deterioration.
References
{{Reflist
External links
Map of the Usoi Dam – Sarez Lake, Scale 1:110'000Map of Gorno-Badakhshan region of Tajikistan
Dams in Tajikistan
Lakes of Tajikistan
Gorno-Badakhshan Autonomous Region
Landslides in Tajikistan
Landslide-dammed lakes
Landslides in 1911