What Is a Tsunami? Simple Explanation

Understanding What a Tsunami Is

A tsunami is a series of large, powerful ocean waves caused by sudden movements under the sea, usually from underwater earthquakes.

How Tsunamis Form

When the ocean floor shifts, it pushes a massive amount of water upward. This energy spreads across the ocean and forms fast-moving waves.

What Causes Tsunamis

Underwater earthquakes: The most common trigger.

Volcanic eruptions: Explosions or collapses can displace water.

Landslides: Falling rock or sediment can push water suddenly.

Meteor impacts: Rare, but capable of generating huge waves.

How Tsunami Waves Move

Tsunami waves travel extremely fast—often over 700 km/h in deep water. They become taller and more dangerous as they reach shallow coastlines.

Effects of a Tsunami

They can flood coastlines, destroy buildings, erode land, and carry debris far inland. Even small tsunamis can be dangerous due to strong currents.

Tsunami Warning Signs

Strong shaking, sudden sea withdrawal, or loud roaring sounds can signal a tsunami. Many regions also rely on official early warning systems.

Why Tsunamis Are Dangerous

They strike quickly, carry enormous energy, and can travel far inland. The combination of speed and height makes them extremely destructive.

The Simple Takeaway

A tsunami is a huge ocean wave caused by sudden underwater movement. Fast and powerful, tsunamis reshape coastlines and require early warnings to save lives.