Tsunami Facts

Here are some facts about Tsunamis:

• Tsunami waves can be very long (as much as 60 miles, or 100 kilometers) and be as far as one hour apart. They are able to cross entire oceans without great loss of energy. The Indian Ocean tsunami traveled as much as 3,000 miles (nearly 5,000 kilometers) to Africa, arriving with sufficient force to kill people and destroy property.


• When the ocean is deep tsunamis can travel unnoticed on the surface at speeds up to 500 miles per hour (800 kilometers per hour), crossing the entire ocean in a day or less.


• The most damaging tsunami on record before 2004 was the one that killed an estimated 40,000 people in 1782 following an earthquake in the South China Sea.


• A tsunami may be less than a foot (30 centimeters) in height on the surface of the open ocean, which is why they are not noticed by sailors. But the powerful shock wave of energy travels rapidly through the ocean as fast as a commercial jet. Once a tsunami reaches shallow water near the coast it is slowed down. The top of the wave moves faster than the bottom, causing the sea to rise dramatically.

These, plus other tsunami facts can be found here.

The picture is of "Churning waters retreat from the battered coast of Kalutara, Sri Lanka, after the December 2004 tsunami drove the ocean more than half a mile (1 kilometer) inland."