Lake tsunamis, like their oceanic counterparts, occur when a large volume of water suddenly changes position in a lake. This phenomenon is increasingly common in areas with mountain glaciers, such as Alaska, USA, and British Columbia, Canada. Lake tsunamis can be generated by seismic activity, landslides, avalanches, glacier ruptures, delta collapses, changes in the atmosphere, and volcanic processes.
While most lake tsunamis currently occur in remote locations with little threat to people or infrastructure, they could become more common in residential areas due to climate change. As temperatures rise and glaciers and permafrost melt, the risk of landslides and lake tsunamis increases. For example, in Alaska, Portage Lake is estimated to have a high risk of a lake tsunami.
Lake tsunamis can cause significant damage, as seen in events like the 2020 landslide in British Columbia that created a 100 m high tsunami. In history, lake tsunamis have resulted in fatalities and destruction, such as the 1938 Lake Michigan tsunami that killed 5 people. The highest tsunami in history, a 524 m wave that hit Alaska in 1958, occurred in a fjord. As these events demonstrate, lake tsunamis have the potential to devastate communities, infrastructure, and natural habitats.