Lake tsunamis are becoming increasingly common in regions with mountain glaciers, such as Alaska and British Columbia. Triggered by landslides into small bodies of water, these tsunamis have primarily occurred in remote locations so far. However, geologist Bretwood Higman of Ground Truth Alaska believes it may only be a matter of time before a more populated area, such as Portage Lake near Whittier, Alaska, is affected.
Higman highlighted other areas in Alaska at risk of lake tsunamis, including Eklutna, Seward, Valdez, Juneau, Grewingk Lake in Kachemak Bay State Park, and Index Lake near Glacier View. Assessing sites like Portage Lake for the possibility of lake tsunamis is crucial, with Higman emphasizing the importance of using distinctive seismic signals connected to landslides to predict and prepare for such events.
At the Seismological Society of America’s Annual Meeting, Higman discussed the emerging hazard of lake tsunamis, linked to climate change. Higher temperatures are melting glaciers that support valley walls, making them more susceptible to landslides into bodies of water. Warming conditions are also affecting permafrost, potentially destabilizing slopes above lakes.
Higman noted the increase in lake tsunamis in recent years, citing the 2020 Elliot Creek tsunami in British Columbia as an example. This event featured a massive landslide and a tsunami runup of more than 100 meters, causing damage to forest and salmon habitat. Although these events have mostly affected remote areas, Higman and his colleagues are studying them to better prepare for tsunamis in regions with infrastructure and larger populations.
Similarities between tectonic faults studied by seismologists and the failure surface of large landslides suggest that studying lake tsunamis could offer insights into fault dynamics. By understanding and detecting precursory seismic signals associated with catastrophic landslides, researchers hope to better predict and mitigate the impact of future tsunamis on communities and infrastructure. As climate change continues to reshape mountain glaciers and affect the stability of valley walls, the risk of lake tsunamis may increase, making proactive assessment and preparation essential.
