Russian and Uzbek experts warn of the danger that threatens several million people in Central Asia. If a strong earthquake happens in the central part of the Pamirs, the waters of Lake Sarez will flood large areas in Tajikistan, Uzbekistan, Afghanistan and Turkmenistan.
Lake Sarez on the territory of the Gorno-Badakhshan Autonomous Region of modern Tajikistan was caused by the earthquake of 1911. The earthquake caused a giant landslide, which blocked the Murgab River and formed a lake at a height of 3250 meters above sea level with a length of 80 kilometers and a maximum depth of 505 meters (Lake Sarez is one of the deepest inland waters in the world). The volume of water in the lake is 17.3 cubic meters. km The height of the Usoi Dam is more than half a kilometer.
“19 million tons of water affect the Usoy Dam in an effort to move it,” said Akram Irgashev, a former Deputy Energy Minister of Uzbekistan. “Only the force of friction keeps him from moving.” However, leaking through the blockage, the water reduces the friction force to zero. Hydraulic pressure creates conditions for a slight rise of the dam. Mr. Irgashev also recalled the report of the Sarez agency operating in Tajikistan: “After many years of temporary lull, Usoy obstruction began to“ breathe ”, to manifest an undoubted tendency to creep and fall.”
However, the main threat comes from part of the destroyed right bank. If the components of its two cubic kilometers of earth and stone fall into the lake, the height of the wave, according to Tajik experts, will reach 100-150 meters. Such a wave will overlap through the blockage and wash it away. Specialists often compare a possible catastrophe in Central Asia with a catastrophe that occurred in Northern Italy in 1963. Then a huge landslide fell in the reservoir Vayont on the river Piave. The giant wave created by this fall in a few minutes completely destroyed the villages of Erto, Cassau and Longarone, in which 2500 people died.
According to the Russian scientist Leonid Papyrin, who worked in Tajikistan, there is 100 times more water in Lake Sarez than in the Vayont reservoir. Mr. Papyrin is the author of the article “Sarez Catastrophe: Geophysical Forecast”. According to him, the volume of the landslide, which can fall into Lake Sarez, is several times larger than the volume that slid into the reservoir in Italy. In addition, the lake is located at a higher altitude than the reservoir. “Accordingly, the consequences of the Sarez catastrophe can be hundreds of times more devastating compared with the tragedy at the reservoir Vayont,” concludes Papyrin.
The breakthrough of the Usoi Dam will lead to the formation of a catastrophic mudslide that will spread through the Murghab, Bartang, Pyanj and Amu Darya rivers to the Aral Sea. The flood will destroy settlements and industrial facilities in Tajikistan, Uzbekistan, Afghanistan and Turkmenistan, as well as frontier guards and military bases. “Six million people live in the danger zone,” says Papyrin. - The greatest number of human victims will be in the territory of Afghanistan and Tajikistan. Maximum material damage will be caused to Turkmenistan and Uzbekistan. ” To eliminate the consequences of such a catastrophe, in his opinion, Central Asian states will need more than one decade.
“A catastrophe can be caused by both an earthquake and sabotage,” says Papyrin. “Therefore, it is impossible to predict its exact date ...” In the 1990s, during the civil war, militants of the United Tajik Opposition threatened to blow up Usoy dam. Former director of the Sredazgidroproekt Institute, Granik Kornakov, said that an earthquake of intensity 9 points or more on a 12-point scale of Merkalli would destroy the right bank of the lake. Lake Sarez is located in a seismically active zone and earthquakes that can cause destruction of the right bank occur every hundred years. The last such earthquake in 1911 gave birth to the lake.
Having studied the Sarez Lake and its right bank, in the beginning of the 80s, Sredazgidroproekt suggested ways to solve the problem - to build tunnels to divert water or to raise the upper part of the dam by 50 meters. However, according to Mr. Kornakov, none of these options today is impossible because of their high cost. “It would be most reasonable to put in order the surveillance and warning systems,” he suggests.
The World Bank is implementing a project in Tajikistan aimed at reducing the threat from Lake Sarez. The implementation of the project, according to the bank, will help “to warn and prepare vulnerable people in the event of a disaster caused by flooding from the shores of Lake Sarez and other frequently occurring natural phenomena”. The project includes the design and installation of monitoring and early warning systems “to save the lives of communities in the valleys of the Murghab and Bartang rivers”. At the end of last year, such systems were installed on the shores of Lake Sarez.
However, some Western experts downplay the risk of destruction of the dam. In the late 90s of the last century, a mission sponsored by one of the United Nations structures declared that the total or even partial destruction of the Usoy Dam was hardly possible, and the threat of destruction of the right bank was less than previously thought. However, the mission still wrote in the report that this threat "remains a distressing reality." “Even a medium-sized wave that overlaps Usoy Dam will affect 7,800 people living in the Bartang River Valley, possibly spreading further than Rushan and causing damage to the first three major cities along the Pyanj River, where 25,000 people live,” the report says missions