The Ocean’s Most Powerful Ripple

A tsunami wave forms when a sudden movement on the ocean floor, like an undersea earthquake, displaces a massive amount of water, sending energy rippling outward in all directions.

Think of it like tossing a rock into a still pond, only this “rock” is the shifting seafloor, and the pond is the entire ocean.

Most tsunamis start with underwater earthquakes, but they can also be triggered by volcanic eruptions, landslides, or even a meteor impact. When the seafloor jolts upward or downward, it pushes the entire column of water above it. That energy spreads out fast, like a ripple on a drumhead.

Here’s the wild part: in the open ocean, a tsunami wave might be only a few feet tall, so small that ships barely notice it passing. But as it nears shore and the ocean gets shallower, all that energy gets squeezed upward. The wave slows down, rises up, and can grow into a towering wall of water moving as fast as a jet plane, up to 500 mph in deep water!

One tsunami in 1958 reached a height of 1,720 feet in a narrow Alaskan bay; that’s taller than the Empire State Building.