In recent years, there have been several landslide tsunamis in the Arctic – most recently in 2017 in the Karrat Fjord in Greenland, where 4 died and 170 had to be evacuated. The inhabitants have still not returned, due to the risk of more landslides in the area.
Now an international research team has gone many thousands of years back in time to investigate what landslides have occurred in an area in West Greenland since the ice that covered all of Greenland during the last ice age retreated approximately 11,000 years ago, so the processes can be better understood.
“To understand the future, we have to look back in time,” says Kristian Svennevig, Senior Researcher at the Geological Survey of Denmark and Greenland (GEUS), who is in charge of the study, which was published in the journal Geology.
“We have put old data together in new ways and thereby found the deposits from nine giant landslides at the bottom of the Vaigat Strait in West Greenland. Our analysis shows that the largest is 8.4 km3 in size, which is completely incomprehensible. It is more than 100 times larger than the landslides we have seen in the last hundred years and definitely not something we expected to find.”
This probably makes the landslide the largest tsunami-generating landslide in the world, excluding those that occur on volcanoes. Calculations show that it may have created a wave up to 280 meters high 25 km away from the landslide. A wave that high would cover most of the Eiffel Tower, which is approx. 330 meters high.
The researchers can see from the deposits that the largest landslides took place in the early Holocene period, i.e. approx. 10,000 years ago. However, further in-depth analyses are required to say more precisely when and what may have triggered them. Kristian Svennevig and his colleagues therefore recommend that more research be done on the subject.
With the expected temperature increases in the Arctic in connection with climate change, the researchers expect that there will be an increase in the number of landslides. Therefore, the researchers recommend looking even further back than ‘historical time’ if we want to understand what can happen in a future where the climatic conditions have no historical precedent.