Can tsunamis occur in lakes?

Tsunamis not only occur in the ocean but can also occur in lakes when a large volume of water changes position suddenly.

Lake tsunami phenomena are becoming increasingly common in places like Alaska, US and British Columbia, Canada, as well as many other regions with mountain glaciers, according to IFL Science . Lake tsunamis can be generated in many ways. Just as ocean tsunamis are often caused by earthquakes beneath or on the seafloor, lake tsunamis can also result from seismic activity . When a lake is located on or near a fault line, earthquakes can impact the lake bed and displace huge amounts of water, creating a tsunami.

Experts believe that lake tsunamis will become increasingly common. (Photo: CGS Graphics).

They can also be produced by landslides , avalanches or glacier ruptures , causing large amounts of debris to fall into relatively small bodies of water, causing the water to rise significantly. Delta collapse is also among the causes of lake tsunamis due to the receding of sand and gravel where the lake meets the river delta. Additionally, changes in the atmosphere and volcanic processes can trigger lake tsunamis.

Although currently, most lake tsunamis occur in remote locations and pose little threat to people or infrastructure, it seems they could return. According to Ground Truth Alaska geologist Bretwood Higman, residential lake tsunamis may become more common , mainly due to climate change. As temperatures soar, forcing glaciers and permafrost to melt, landslides will become increasingly common, leading to a higher likelihood of lake tsunamis. In Alaska, geologists estimate a high lake tsunami risk in Portage Lake.

No matter where they occur, lake tsunamis can cause disaster. In November 2020, a massive landslide caused a 100m high lake tsunami in British Columbia. About 18 million cubic meters ^of rock fell directly into the glacier lake, sending rushing water into Elliot Creek and the surrounding area, devastating the land. "Imagine a landslide with a mass equivalent to all the cars in Canada, moving at 140km/h as it swept across a large lake ," geomorphologist Marten Geertsema described in 2022.

In the above case, the damage mainly fell on forested areas and salmon spawning areas, but such an event had the potential to wipe out homes and infrastructure, and even kill people. For example, the 1938 Lake Michigan tsunami killed 5 people and injured 27 with a 3m high wave that suddenly appeared.

In fact, the highest tsunami in history, a 524 m wave that hit Alaska in 1958, occurred in a fjord.