Tsunamis triggered by landslides are becoming increasingly common

Landslide-induced tsunamis are becoming more frequent with global warming

The Earth is warming rapidly due to human activities that are pumping greenhouse gases into the atmosphere. And as glaciers and permafrost melt, these destabilizing forces are leading to more landslides. Some of these landslides, in turn, enter bodies of water, displacing them and triggering huge waves known as tsunamis. These landslide-triggered tsunamis are also called megatsunamis. And due to climate change, they are becoming more and more common.

A group of researchers led by Angela Carrillo-Ponce from the German Research Centre for Geosciences GFZ in Potsdam published a new paper on August 8, 2024. The paper appeared in the peer-reviewed journal The seismic recordingThe authors wrote:

The impacts of global warming and changes in permafrost are likely to further reduce slope stability and increase the frequency of landslides and tsunamis. The occurrence and spread of tsunamis, especially in fjord areas, is considered one of the most devastating natural disasters ever.

September 16, 2023, Greenland Megatsunami

The authors studied the megatsunami of September 16, 2023, which generated a unique seismic signal in remote eastern Greenland. The waves from this tsunami were more than 200 meters high at their peak. And along a 10-kilometer stretch of the fjord, they averaged 60 meters high. In fact, the megatsunami was so strong that the waves sloshed back and forth between the shores of Dickson Fjord for a week.

Carrillo-Ponce said:

It is exciting that the signal from a landslide-induced sloshing wave in a remote area of ​​Greenland can be observed worldwide and for over a week.

Because it was a remote area, the only reported damage was to a military facility on the island of Ella, which was closed and unmanned over the winter.

Carrillo-Ponce said:

Analyzing the seismic signal can give us some answers about the processes taking place and could even help improve monitoring of similar events in the future.

And the press release continued:

The findings will help researchers study the impact of landslides in Greenland and similar regions around the world, where global warming and loss of permafrost are making rocky slopes and glaciers increasingly unstable.

Tsunami in Alaska in August 2024

Receding glaciers expose rocky cliffs that are prone to landslides. In August, heavy rain in southern Alaska also triggered a landslide in Kenai Fjords National Park, which then triggered a tsunami. About 2 million cubic meters of rock and debris crashed into Pederson Lagoon, triggering a 17-meter-high tsunami. NASA Earth Observatory reported:

The wave damaged trees and flattened vegetation between the upper and lower parts of Pedersen Lagoon. According to local reports, it also damaged the wooden dock of a lodge on the east side of the lower lagoon.

Tsunami risk

The landmass that caused the Alaska landslide and tsunami is an area that scientists had already identified as a potential problem. They had planned to conduct field research there before the event. In fact, they narrowly missed the observations beforehand. Chad Hults, regional geologist for the National Park Service (NPS) Alaska, told KTUU in Anchorage:

We had planned a flight to survey tidewater glaciers the week before, but were unable to continue the operation that day due to a technical problem and therefore were unable to collect the data before the landslide started.

Hults said the National Park Service and USGS are currently investigating other areas in Alaska where landslides may have caused tsunamis:

We have identified some unstable slopes that are above retreating glaciers. The debris could potentially break off, land on the glacier and then flow down the glacier before reaching the water.

People in these regions, where the slopes become unstable, should consider the landscape when deciding where to camp or boat. Hults said:

Southern Alaska has very steep slopes that may be unstable. Being aware of this danger is important in your decision-making.

Conclusion: Tsunamis triggered by landslides due to melting glaciers and permafrost are becoming more frequent with global warming.

Source: The Greenland megatsunami of September 16, 2023: Analysis and modeling of the source and a week-long monochromatic seismic signal

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