Research published in Scientific Reports has shown that melting glaciers caused by global warming has seen an increase in, and severity of, landslide tsunamis.
In the research, scientists use the example of Tyngdall Glacier landslide that sent 180M.t of rock into Taan Ford in Alaska. The resulting tsunami reached elevations as high as 193 m, one of the highest tsunami runups – the extent water rushes up the surrounding coast - ever documented worldwide.
The report states: “Climate change is driving worldwide glacial retreat and thinning that can expose unstable hillslopes. The removal of glacial ice supporting steep slopes combined with the thawing of permafrost in alpine regions increases the likelihood of landslides
“Glaciers undercut slopes, priming them for failure by deepening and widening valley bottoms, and by producing steeper valley walls. Additionally, ice loading produces stress fractures in the underlying bedrock, further preparing slopes for failure. As climate warms and glaciers shrink and retreat, they can no longer support rock slopes, and fractures expand as stresses are released. This slope conditioning leads to rock falls, deep-seated gravitational slope deformation, and occasionally catastrophic rock avalanches.”
The research also warns of the creation or extension of deep water where tsunamis can be generated efficiently. This is particularly prevalent along the coastlines of Alaska, Patagonia, Norway, and Greenland, where communities, tourism, and infrastructure are becoming increasingly exposed to landslides and the possible tsunamis they may generate. Also tsunamis in lakes can create flood risk downstream by flowing into inhabited downstream valleys, says the report.
Author Dan Shugar of the University of Washington said: “We need to better understand the risk posed by these steep slopes in a changing climate. Our results call attention to an indirect effect of climate change that is increasing the frequency and magnitude of natural hazards near glaciated mountains.”