A catastrophic landslide in Greenland triggered a deadly tsunami in 2017, and scientists are concerned that two newly analyzed unstable slopes in the area could cause another disaster.
The 2017 event struck the abandoned village of Nuugaatsiaq with a run-up of about 10 meters, killing four inhabitants and injuring nine others after 58 million cubic meters of rock fell from Ummiammakku Mountain into Karrat Fjord.
The hazard was evaluated in a study shared in Communications Earth & Environment by Marie Keiding alongside peers representing the Norwegian Geotechnical Institute and the Geological Survey of Denmark and Greenland. A large slope in Karrat Fjord sits just 3 kilometers west of the 2017 avalanche and spans 2.65 million square meters above sea level.
Researchers estimate this massive slope contains about 400 million cubic meters of unstable material waiting to fall. This volume makes it one of the largest mapped active unstable slopes on Earth. A second, smaller slope in Kangerluarsuk Fjord poses a more immediate threat by displacing around 30 million cubic meters of mountain.
The Kangerluarsuk Fjord slope was barely visible prior to 2015, but it has developed rapidly and may even be accelerating. Authors of the study note that a full or partial collapse as a translational rockslide is probable over the coming years or decades, even though predicting the precise moment is extremely difficult.
A failure at this site could generate a wave run-up of 3 to 7 meters at the settlement of Ukkusissat, located roughly 25 kilometers away. The resulting wave would arrive just 6 minutes after the initial landslide.
If the entire unstable slope in Karrat Fjord were to fail, tsunamis as tall as telephone poles could ricochet across the entire Uummannaq Fjord system. While deep-seated deformation appears relatively slow, a total collapse cannot be excluded.
According to the investigators, an occurrence of this scale has the potential to produce a tsunami with run-ups topping 10 meters at a distance exceeding 100 kilometers, highlighting the extensive reach of such a disaster. Scientists suspect climate change plays a part in this growing risk by melting permafrost in Arctic and high-mountain areas.
