A new study has suggested that landslides and mudslides likely to remain a significant threat in Nepal for months and the risk is likely to increase when the monsoon rains arrive this summer.
University of Michigan geomorphologist Marin Clark and two colleagues have assessed the landslide hazard in Nepal and looked for locations where landslides likely occurred during the earthquake, as well as places that are at high risk in the coming weeks and months. The analysis revealed tens of thousands of locations at high risk.
Clark said that the majority of them have already happened and came down all at once with the shaking on Saturday, but there will still be slopes that have not yet failed but were weakened. So there will be a continued risk during aftershocks and with the recent rainfall and again when monsoon rains arrive this summer.
Information from the U-M-led study has been shared with the U.S Geological Survey, NASA, the U.S. Agency for International Development and other responding agencies. It is being used help prioritize both satellite observations and the analysis of data from those satellites, said Clark, an associate professor in the U-M Department of Earth and Environmental Sciences.
Clark noted that the satellites looked first at places where lots of people live, including Kathmandu and the foothills areas to the south, adding those areas do not look significantly impacted by landsliding, but they're worried about the high country.
The region at highest risk for landslides and mudslides is the mountainous area along the Nepal-Tibet border, north of Kathmandu and west of Mount Everest, directly above the fault rupture. The highest-risk zone is at elevations above 8,200 feet in a region that covers 17,550 square miles, which is roughly twice the size of Massachusetts.
Landslides in mountainous regions can also block river valleys, creating a significant flooding hazard. Water builds up behind those dam-like structures, creating the potential for catastrophic flooding if the dams are overtopped and then fail.
Clark added with the satellite images, they'll be looking first at the highest-risk landslide areas that are close to big rivers. Those locations are high priorities.
