A landslide dam or barrier lake is the natural

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aqua ...

ming of a

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

by some kind of

landslide Landslides, also known as landslips, rockslips or rockslides, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, mudflows, shallow or deep-seated slope failures and debris flows. Landslides ...

, such as a

debris flow Debris flows are geological phenomena in which water-laden masses of soil and fragmented Rock (geology), rock flow down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits on valley floors. ...

, rock avalanche or

volcanic eruption A volcanic eruption occurs when material is expelled from a volcanic vent or fissure. Several types of volcanic eruptions have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior h ...

. If the damming landslide is caused by an

earthquake An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

, it may also be called a quake lake. Some landslide dams are as high as the largest existing artificial dam.Robert B. Jansen (1988) "Advanced Dam Engineering for Design, Construction, and Rehabilitation",

Causes

The major causes for landslide dams investigated by 1986 are landslides from excessive

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...

and

s, which account for 84%. Volcanic eruptions account for a further 7% of dams. Other causes of landslides account for the remaining 9%.

Consequences

The water impounded by a landslide dam may create a dam reservoir (

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

) that may last for a short time, to several thousand years. Because of their rather loose nature and absence of controlled

spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure tha ...

, landslide dams frequently fail catastrophically and lead to downstream

flooding A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant concern in agriculture, civi ...

, often with high casualties. A common failure scenario is overflowing with subsequent dam breach and erosion by the overflow stream. Landslide dams are responsible for two types of

flood A flood is an overflow of water (list of non-water floods, or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant con ...

ing: backflooding ( upstream flooding) upon creation and downstream flooding upon failure. Compared with catastrophic downflooding, relative slow backflooding typically presents little life hazard, but property damage can be substantial. While the dam is being filled, the surrounding

groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...

level rises. The dam failure may trigger further catastrophic processes. As the water level rapidly drops, the uncompensated groundwater

hydraulic pressure Hydraulics () is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counterpart of pneumatics, which concer ...

may initiate additional landslides. Those that fall into the dam reservoir may lead to further catastrophic spillages. Moreover, the resulting

may undercut the sides of the river

valley A valley is an elongated low area often running between hills or mountains and typically containing a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over ...

to further produce landslides downstream. After forming, the dam leads to

aggradation Aggradation (or alluviation) is the term used in geology for the increase in land elevation, typically in a river system, due to the deposition of sediment. Aggradation occurs in areas in which the supply of sediment is greater than the amount o ...

of the valley upstream, and dam failure leads to aggradation downstream. Construction engineers responsible for design of artificial dams and other structures in river valleys must take into account the potential of such events leading to abrupt changes in river's regimen.

Examples

*The highest known landslide dam of historic times is the

Usoi Dam The Usoi Dam is a natural landslide dam along the Murghab River (Tajikistan), Murghab River in Tajikistan. At high, it is the tallest dam in the world, either natural or man-made. The dam was created on 18 February 1911, when the 7.4-Surface wav ...

in modern

Tajikistan Tajikistan, officially the Republic of Tajikistan, is a landlocked country in Central Asia. Dushanbe is the capital city, capital and most populous city. Tajikistan borders Afghanistan to the Afghanistan–Tajikistan border, south, Uzbekistan to ...

created by a landslide triggered by an

on February 18, 1911. It dammed the Murghab River to the height of to impound

Sarez Lake Sarez Lake ( ) is a lake in Rushon District of Gorno-Badakhshan province, Tajikistan. Its length is about , its depth about a few hundred meters, its water surface elevation about above sea level, and volume of water over . The mountains around ...

deep. * Lake Waikaremoana in

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

was formed by a high landslide dam believed to be 2,200 years old. Between 1935 and 1950 the landslide was tunneled and sealed to stabilise it so it could be used for

hydroelectric Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...

power generation. This appears to be the first example of modification of a natural landslide dam for power generation. * Attabad Lake in Pakistan was formed by a landslide in 2010. ( high) *The Red Lake (Romanian: '' Lacul Roşu'') is a barrier lake in the

Eastern Carpathians Divisions of the Carpathians are a categorization of the Carpathian mountains system. Below is a detailed overview of the major subdivisions and ranges of the Carpathian Mountains. The Carpathians are a "subsystem" of a bigger Alps-Himalaya Sy ...

chain in Harghita County, Romania. The name of "Lacul Roşu" comes from the reddish alluvia deposited in the lake by the Red Creek. *The Gros Ventre landslide is an example of a huge, short-lived and devastating landslide dam, ( high). *The Lynmouth Flood of 15-16 August 1952 was partly the result of the formation and subsequent failure of a landslide dam on the East Lyn River, sending a wave of water and debris into the town and killing 34 people. * Quake Lake, created in Montana in 1959, ( high). *The Tangjiashan Lake, a dangerous "quake lake", was created as a result of the

2008 Sichuan earthquake An earthquake occurred in the province of Sichuan, China at 14:28:01 China Standard Time on May 12, 2008. Measuring at 8.0 (7.9–8.3 ), the earthquake's epicenter was located boxing the compass, west-northwest of Chengdu, the provincial ...

. It was located in the extremely rugged terrain of Tangjiashan Mountain. Chinese engineers, scientists, and soldiers were involved in the digging of a sluice to alleviate the dangers of this one of 34 landslide dams created by the magnitude 8.0

Sichuan Sichuan is a province in Southwestern China, occupying the Sichuan Basin and Tibetan Plateau—between the Jinsha River to the west, the Daba Mountains to the north, and the Yunnan–Guizhou Plateau to the south. Its capital city is Cheng ...

earthquake. On June 10, 2008, the lake started to drain via the sluice, flooding the evacuated town of Beichuan. ( high) *The Riñihuazo begun on 22 May 1960, after a landslide caused by the Great Chilean earthquake blocked Riñihue Lake's outflow. According to the chronicler Mariño de Lobera a similar event occurred after the 1575 Valdivia earthquake. ( high) *The 2014 Oso mudslide dammed the Stillaguamish River in March 2014, creating a lake that blocked Washington State Route 530 and hampered rescue/recovery efforts. *Among the most destructive landslide lake outburst floods in recorded history occurred in the Sichuan province on 10 June 1786, when the dam on the Dadu River burst, causing a flood that extended downstream and killed 100,000 people.Schuster, R.L. and G. F. Wieczorek, "Landslide triggers and types" in ''Landslides: Proceedings of the First European Conference on Landslides'' 2002 A.A. Balkema Publishers. p.66 *The largest landslide dam in Britain impounds Tal-y-llyn Lake (Llyn Mwyngil) beside

Cadair Idris Cadair Idris or Cader Idris is a mountain in the Meirionnydd area of Gwynedd, Wales. It lies at the southern end of the Snowdonia National Park near the town of Dolgellau. The peak, which is one of the most popular in Wales for walkers and hikin ...

in Snowdonia National Park, Wales. It was first recognised by E Watson in 1962. It is probably over 10,000 years old. *Moklishko Ezero in North Macedonia *Trebenishko Ezero, near Trebenishta in North Macedonia *The

1139 Ganja earthquake The 1139 Ganja earthquake was one of the worst seismic events in history. It affected the Seljuk Empire and the Kingdom of Georgia, in modern-day Azerbaijan and Georgia (country), Georgia. The earthquake had an estimated magnitude of 7.7 , 7.5 an ...

triggered a massive landslide on Mount Kapaz, damming the Kürəkçay River, forming Lake Göygöl. The earthquake resulted in as many as 300,000 deaths.

References

{{Authority control Dams by type Landslide analysis, prevention and mitigation