A giant 500-meter megatsunami struck Alaska after a mountain collapsed into a fjord — and cruise ships narrowly avoided disaster.

Scientists have revealed new details about a terrifying “megatsunami” in Alaska that generated one of the tallest waves ever recorded on Earth — a massive wall of water created when part of a mountain collapsed into a remote fjord.

The event occurred last summer in Tracy Arm Fjord in southeastern Alaska, but new scientific analysis now shows just how extreme the disaster really was.

A Wave Nearly 500 Meters Tall

Researchers say the collapse sent around 64 million cubic meters of rock crashing into the fjord in less than a minute. The impact generated a gigantic wave estimated at nearly 500 meters high, making it the second-largest megatsunami ever recorded.

To understand the scale, the wave was taller than many of the world’s most recognizable skyscrapers and landmarks.

Scientists say the timing of the event likely prevented a catastrophe. The collapse happened during the early morning hours, when tourist cruise ships were not present inside the fjord.

A “Close Call” for Tourists

Geologist Bretwood Higman described the event as a “close call,” warning that people were dangerously close to being caught in the disaster zone.

Tracy Arm is a popular destination for cruise tourism, known for its towering cliffs, glaciers, and dramatic scenery. Had ships been inside the fjord when the wave struck, the consequences could have been catastrophic.

How the Megatsunami Happened

Unlike ocean-wide tsunamis caused by major earthquakes, megatsunamis form when enormous landslides crash directly into enclosed bodies of water such as fjords or lakes.

In this case, scientists believe glacier melt played a critical role. As glaciers retreated, they removed support from unstable mountainsides, allowing huge sections of rock to collapse.

Researchers from University College London said the glacier had effectively been holding part of the cliff in place. Once the ice melted away, the rock face became unstable and eventually failed.

Climate Change Increasing the Risk

Scientists warn that warming temperatures and accelerating glacier retreat are making such events more likely.

Alaska is especially vulnerable due to its steep mountains, narrow fjords, active geology, and rapidly melting glaciers. Researchers now fear that megatsunamis could become significantly more frequent in coming decades.

Some experts believe these events may already be occurring many times more often than they did only a few decades ago.

Calls for More Monitoring

Following the disaster, scientists are urging wider hazard monitoring across vulnerable regions of Alaska.

Some cruise companies have reportedly decided to stop sending ships into Tracy Arm because of safety concerns linked to future landslides and waves.

A Stark Warning From Nature

The Alaska megatsunami highlights a growing reality: climate-driven environmental change is reshaping some of the planet’s most dramatic landscapes in dangerous ways.

What happened in Tracy Arm was not just a geological event — it was a warning about how quickly entire mountainsides can collapse when glaciers disappear.