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Sarez Lake: Created by a 1911 Earthquake
Sarez Lake Information and Facts
Sarez Lake is located deep in the inaccessible Pamir Mountains, in the Rushon district of the Gorno-Badakhshan Province in Central Tajikistan. It is Tajikistan’s largest naturally formed rock-dammed lake.
Formation and Geography
Sarez Lake was formed in 1911 after a great earthquake measuring 6.5-7 on the Richter scale. The result of this earthquake was a massive landslide of 2.2 million square-meters, which formed the 5 kilometers long, 3.2 kilometers wide Usoi Dam, which blocked the Murghab River. It is the tallest dam in the World, with a height of 567 meters. In April 1914 the lake’s levels rose high enough to flow over. Sarez Lake reached its current water level in 1920.
The valley the lake is situated in can be considered relatively young from a geological point of view. It is deep, narrow and has steep slided slopes. The inflowing and outflowing amount of water balances each other in the lake.
The lake’s stability is questionable, considering local seismic activity and the fact that Sarez is located in one of the most earthquake-prone regions in the World. According to scientists, Usoi dam would be unsteady if an earthquake occurred in the future, and it would probably cave in case of increased flooding. Since the valley below the dam is narrow, the floods in the area would be very destructive. A potential flooding could affect the lives of more than 5 million people living around the Bartang, Panj and Amu Darja rivers, affecting not only the population of Tajikistan, but also inhabitants of Afghanistan, Uzbekistan and Turkmenistan.
Another threat is the result of the filtrating water, which created cavities inside the dam, which might destabilize Usoi’s walls. The 3 km3 detached rock mass at the edge of the lake could fall into its waters any time, creating a huge wave, adding additional pressure to the dam which would most probably collapse.
Although many believe that Usoi dam is balanced enough to resist erosion, it is unkwnown whether it can withstand a big earthquake. The area has been monitored since 2004 for surging water levels and other geographic events. Some proclaim that because of the limited funding and the remoteness of the area, this level of monitorization is not sufficient.