On 17 October 2015, a landslide near the end of the Tyndall Glacier in Alaska sent 180 million tonnes of rock plunging into a body of water called Taan Fiord. A couple of kilometres away, on the other side of the valley, the resulting wave reached a height of193 metres, according to a new study of the site. That鈥檚 one of the highest tsunamis ever recorded.
The landslide was caused by the retreat of the glacier, say the researchers, likely as a result of global warming. That means as Earth heats up, the risk of such landslide-triggered tsunamis rises, they warn.
Glaciers carve out steep-sided valleys, and there is usually a fjord or lake where the glacier ends. As glaciers around the world retreat because of climate change, they are leaving unstable slopes poised above the water. The thawing of the exposed mountainsides can destabilise them further.
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Fortunately, the areas at risk are remote and sparsely populated, and the tsunamis created by these landslides weaken rapidly with distance, unlike tsunamis caused when earthquakes displace large areas of seafloor.
鈥淏ecause the source is so localised, it will diminish as the wave spreads out,鈥� says team member Bretwood Higman of the nonprofit organisation Ground Truth Trekking.
Nevertheless, there is still potential for disaster. 鈥淭here was a similar tsunami in Greenland in 2016 that destroyed a small village and killed 4 people,鈥� says Higman. 鈥淚 live near a site where a busy summer day might put hundreds in harms way, and in Glacier Bay [in Alaska] there are potentially several thousand people at a time in cruise ships visiting areas where landslide tsunamis are likely.鈥�
Scientific Reports
