On the night of 5/6 February 1911 a 7.4 magnitude earthquake struck the Rushon district of the Gorno-Badakshan province of Tajikistan. The village of Usoi was buried by a landslide, causing 54 deaths. The landslide of ~2 million cubic metres also filled the valley of the Murghab River, producing a natural dam, 3km long and 550m high, reputedly the largest natural dam in the world. This dam has resulted in the formation of Lake Sarez, about 65km long and containing 18 cubic kilometres of water. There is the risk that a future earthquake will cause a similar landslide to enter the lake and cause a failure of the dam.

The three-dimensional view is from Google Earth (38.28N, 72.60E) and the overview of Lake Sarez is from flashearth (the natural dam is at the NW end of the lake). Third image is taken from the NASA Earth Observatory image.