A tsunami is a series of sea waves caused by underwater earthquakes, landslides or volcanoes. Tsunami can travel at speeds up to 450 miles perhour and waves range in height from a harmless few inches to 100 feet. Its 100-foot waves killed more than 36,000 people on the coasts of Java and Sumatra. Hours later, it reached Hawaii, where it killed 159 people. About 200 people died.
Tsunami can occur anywhere, but are most common in the Pacific Ocean.
Use of the Japanese name for waves reflect the fact that Japan has been the most affected country, with more than 100,000 deaths recorded in about 250 tsunamis over the centuries.