Weather 101: Tsunami

On Boxing Day 2004 (December 26), a catastrophic earthquake and tsunami struck the Indian Ocean and caused massive destruction to 14 countries.

Hat Rai Lay Beach in southern Thailand as water moves out right before the tsunami hits. Image: AFP/Getty Images

275,000 people lost their lives and the damage is estimated to total around U.S. $9.9 billion. With a speed over 300 miles per hour, the wall of water destroyed 141,000 houses and reached heights up to 100 feet.

What Is A Tsunami?

A tsunami, also known as a tidal wave or harbor wave or seismic wave, is caused by a sudden shift in the seafloor in the ocean by an earthquake, landslide, or volcanic activity.

In the case of the 2004 Indian Ocean Tsunami, an earthquake along a fault line caused the seafloor to shift suddenly. Ocean water was forced up vertically to the surface and spread out in all directions.