Massive Alaska Megatsunami Triggered by Landslide in Tracy Arm Fjord

Recent scientific analysis has revealed that a massive landslide in Alaska’s Tracy Arm fjord generated a megatsunami reaching 500 meters in height. The event, which occurred in a region frequently visited by tourists, is now recognized as the second largest tsunami ever recorded in history.

The wave was triggered by a colossal volume of rock and debris that collapsed from the surrounding cliffs into the narrow waters of the fjord. Because of the confined geography of the Tracy Arm, the displaced water was forced upward rather than outward, creating a wall of water that exceeded the height of the Empire State Building.

Researchers have identified this event as a megatsunami, a category of wave distinct from the more common seismic tsunamis. While typical tsunamis are caused by the displacement of the seafloor during an earthquake, megatsunamis are generally the result of massive landslides, volcanic collapses, or asteroid impacts that displace water on a concentrated scale.

Climate Change and Slope Instability

Studies indicate that the landslide which triggered the wave was linked to the effects of climate change. Rising global temperatures have accelerated the melting of glaciers and the degradation of permafrost in the Alaskan wilderness, both of which act as structural supports for steep mountain slopes.

As glaciers retreat, they leave behind unsupported rock walls that are susceptible to failure. The loss of ice pressure, combined with increased water infiltration from melting ice and heavier rainfall, destabilizes these slopes, making catastrophic landslides more probable in fjord environments.

This pattern of instability is not isolated to Tracy Arm. Geologists have noted similar trends across other high-latitude regions, where the intersection of steep topography and rapid warming increases the risk of landslide-generated waves that can devastate coastal areas and tourist hubs.

Scientific Recreation and Landscape Analysis

To understand the scale of the event, researchers used computational modeling to recreate the megatsunami’s progression through the fjord. These simulations allowed scientists to map the exact trajectory of the wave and the force with which it struck the opposing shoreline.

Data provided by NASA Science has detailed the post-tsunami landscape of Tracy Arm, showing significant geological scarring and the redistribution of sediment. The force of the 500-meter wave stripped vegetation and soil from the cliffs at elevations where such events were previously thought impossible.

The analysis of the debris field and the “trim line”—the visible mark on the landscape where the wave’s crest reached—confirmed the wave’s extreme height. This evidence allows researchers to compare the Tracy Arm event to the 1958 Lituya Bay tsunami, which remains the largest ever recorded.

Implications for Coastal Safety

The findings highlight the vulnerability of major tourist areas located within fjords and steep-walled inlets. Because these events are triggered by landslides rather than tectonic shifts, they often occur without the long-range warning signs associated with traditional tsunamis, such as a receding shoreline or a detectable earthquake.

The speed and height of a megatsunami in a confined space leave very little time for evacuation. The Tracy Arm event serves as a case study for how geological instability, compounded by environmental shifts, can create localized but catastrophic hazards in regions that are otherwise perceived as stable.

Geological surveys are now being expanded in similar regions to identify other “at-risk” slopes that could potentially trigger similar waves. This effort aims to provide better risk assessments for cruise ship operators and regional authorities who manage tourism in Alaska’s fjord systems.