Massive Alaska megatsunami was second largest ever recorded

A massive megatsunami struck a remote fjord in southeast Alaska last summer after a colossal landslide sent 64 million cubic meters of rock crashing into the water, generating a wave nearly 500 meters high—the second tallest ever recorded. The event occurred near the South Sawyer Glacier in Tracy Arm Fjord, an area popular with cruise ships, but the timing in the early morning prevented a potential disaster involving tourists. Scientists have now analyzed the incident using fieldwork, seismic data, and satellite imagery to understand the scale and causes of the megatsunami. The landslide was triggered by the collapse of a mountain cliff, which had been destabilized by glacier retreat. Researchers found that the glacier had previously supported the rock face, and as it melted due to climate change, the exposed cliff became vulnerable to sudden collapse. The resulting wave caused significant environmental damage, including uprooted trees and stripped vegetation along the fjord’s steep terrain. Dr. Bretwood Higman, an Alaskan geologist who visited the site, described the event as a "close call" and expressed concern about future risks, noting the narrow escape of people who might have been in the area. Megatsunamis like this are typically localized phenomena caused by landslides or volcanic activity, differing from the more widespread tsunamis generated by underwater earthquakes, such as the 2011 Japan tsunami. Alaska’s geography—with its steep mountains, narrow fjords, and frequent seismic activity—makes it particularly susceptible to such events. The recent megatsunami underscores the increasing hazards posed by climate change, as glacier melt can destabilize rock formations and trigger catastrophic landslides. The new findings, published in the journal Science, highlight the urgent need for monitoring vulnerable areas in Alaska and elsewhere. Scientists warn that as glaciers continue to retreat, the risk of similar or even larger megatsunamis may increase, posing significant threats to both natural environments and human activities in these regions.