Dammed by landslides
Satellite images have helped locate zones in Nepal and China where landslides can cause huge damage. The hazards these pose could be even bigger than the Nepal earthquake. They can block rivers, create avalanches and cause floods. In one such case, the Kali Gandaki was dammed by a landslide in Nepal and an artificial lake was created, forcing the government in Bihar (which lies downstream) to issue a flash flood alert on May 23. Response teams from various organisations, including NASA, non-profit Earthquake Without Frontiers, British Geological Survey and the International Centre for Integrated Mountain Development, have identified over 3,000 landslides and large mass movements in the region. Of these, a database of 250 sites (depicted in the map) has been created. Four of them pose a grave threat
Pisang (Nepal): The Nepal earthquake created a landslide dam on the Marshyangdi river, 1.8 km upstream of the Lower Pisang village. Satellite images show the lake is expanding.
Manaslu region (Nepal): Tom Khola, a tributary of the Burhi Gandak, has been dammed by a landslide, resulting in a lake in the Manaslu region. The landslide is at a height of 2,500 m. Though the landslide has not harmed any village, the threat is there because the new lake is upstream of the villages of Ghapsya (5 km) and Ghap (6 km). The landslide dam is also just 6 km from the Nepal-Tibet border. So if the lake keeps growing, it will become a concern to China.
Langtang valley (Nepal): Maps prepared by the University of Arizona and NASA show that the Langtang valley has extremely high ice avalanche susceptibility due to the presence of Himalayan slopes, glaciers and increased shaking during an earthquake (which happens because of its elevation). The residents of the area have experienced ice and debris avalanches, which is in line with the results found in the susceptibility map.
Chongsecun (China): Canadian, American, Chinese, Swiss and British investigators are examining a landslide in Tibet at an elevation of 2,600 m. This landslide has dammed the Gyriong Zangbo river and blocked a road between Nepal and Tibet. The debris has been displaced downslope, forming a 700 m long landslide scar.