Massive Alaska megatsunami was second largest ever recorded

A massive megatsunami triggered by a colossal landslide in southeast Alaska last summer has been identified as the second tallest ever recorded, generating a wave nearly 500 metres high. The event occurred when approximately 64 million cubic metres of rock—equivalent to 24 Great Pyramids—collapsed into the Tracy Arm Fjord, creating a devastating wave that swept through the remote area. Fortunately, the timing of the landslide in the early morning hours prevented cruise ships, which frequently visit the fjord, from being caught in the disaster. Scientists emphasize the narrow margin by which a major human tragedy was averted. The landslide and resulting megatsunami were caused by the sudden collapse of a mountain face previously supported by glacier ice. Researchers from University College London and other institutions combined field observations, seismic data, and satellite imagery to reconstruct the event and its aftermath. The retreat of the glacier, driven by climate change and rising temperatures, exposed the cliff base, destabilizing the rock and triggering the collapse. On arrival weeks later, geologists observed extensive damage, including stripped vegetation and broken trees scattered across the mountainside and fjord. Megatsunamis like this one are distinct from typical oceanic tsunamis caused by earthquakes or underwater volcanic activity. They tend to be highly localized, dissipating quickly but producing extraordinarily high waves in confined fjord or lake environments. Alaska’s steep terrain, narrow fjords, and seismic activity make it particularly susceptible to such events. The 1958 Lituya Bay megatsunami, which generated a wave over 500 metres tall, remains the largest recorded, with this recent event ranking second. Experts warn that as glaciers continue to melt due to climate change, the risk of similar landslide-induced megatsunamis may increase, posing significant hazards to both local ecosystems and human activities such as tourism. Dr Bretwood Higman, who surveyed the site, expressed concern about future risks, highlighting the need for improved monitoring and preparedness in vulnerable regions. The findings underscore the complex interplay between climate change, geological instability, and natural disaster risk in Alaska’s dynamic environment.