Quick facts about tsunami

(Courtesy from national geographic)

• 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.


• A tsunami is not a single wave but a series of waves, also known as a wave train. The first wave in a tsunami is not necessarily the most destructive. Tsunamis are not tidal waves


• Tsunami (pronounced soo-NAH-mee) is a Japanese word. Tsunamis are fairly common in Japan and many thousands of Japanese have been killed by them in recent centuries.


• 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. Scientists are able to calculate arrival times of tsunamis in different parts of the world based on their knowledge of when the event that generated them occurred, water depths, and distances.


• Tsunamis do not necessarily make their final approach to land as a series of giant breaking waves. They may be more like a very rapidly rising tide. This may be accompanied by much underwater turbulence, sucking people under and tossing heavy objects around. Entire beaches have been stripped away by tsunamis.


• Geological features such as reefs, bays, river entrances, and undersea formations may dissipate the energy of a tsunami. In some places a tsunami may cause the sea to rise vertically only a few inches or feet. In other places tsunamis have been known to surge vertically as high as 100 feet (30 meters). Most tsunamis cause the sea to rise no more than 10 feet (3 meters).


• A tsunami is a series of great sea waves caused by an underwater earthquake, landslide, or volcanic eruption. More rarely, a tsunami can be generated by a giant meteor impact with the ocean.


• The 2004 Indian Ocean tsunami could rank as the most devastating on record. News reports so far suggest that more than 40,000 people may have lost their lives, many of them washed out to sea. Some experts believe the final toll may be as high as 60,000 people dead.


• Many people were killed by the Indian Ocean tsunami because they went down to the beach to view the retreating ocean exposing the seafloor. Apparently they were unaware that this phenomenon precedes a killer wave. Experts believe that a receding ocean may give people as much as five minutes' warning to evacuate the area.


• Because tsunamis can approach the shore as fast as 100 miles per hour (160 kilometers per hour) it is often too late to get away if you see one. An approaching tsunami is not something to be admired unless you are safely on high ground.


• Remember that a tsunami is a series of waves and that the first wave may not be the most dangerous. The danger from a tsunami can last for several hours after the arrival of the first wave. A tsunami wave train may come as a series of surges that are five minutes to an hour apart. The cycle may be marked by a repeated retreat and advance of the ocean. Stay out of danger until you hear it is safe

**More info about tsunami from National Geographic

Quick Links
The Deadliest Tsunami in History. (with Video Clips-Updated)
Ways of helping Tsunami victims in Southern Asia.
What to do when tsunami happen?