Tsunami

A tsunami is a series of very long ocean waves caused by the sudden displacement of a large volume of water, most often by an undersea earthquake, but also by volcanic eruptions or landslides.

How tsunamis form

When the sea floor shifts abruptly, it pushes the water above it, sending waves outward in all directions. In deep water the waves travel fast but are low; as they reach shallow coasts they slow down and grow into towering walls of water.

Effects

Tsunamis can cause severe destruction along coastlines. The 2004 Indian Ocean tsunami killed over 200,000 people across several countries.

Warning systems

Many coastal nations now operate tsunami warning systems using seismic sensors and ocean buoys.

Frequently asked questions

What causes a tsunami?

Usually an undersea earthquake that suddenly displaces ocean water.

Are tsunamis the same as tidal waves?

No; tsunamis are caused by geological events, not tides.