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 The destructive effects of tsunamis on islands and coastal areas directly result from three factors: (1) inundation (flooding and floating debris); (2) wave impact on structures, ships, and port facilities, and (3) erosion of foundations leading to collapse of bridges, seawalls, and buildings.                Indirect factors of tsunami casualties come from (1) fires initiated in buildings, ships, oil tanks, and gas stations; (2) environmental pollution caused by sewage, oil, and dangerous chemicals; and (3) outbreak of epidemic diseases. All these lead to tragic loss of life, damage to property, and destruction of ports, towns, and villages.

All along the margin of the Pacific Ocean, there are subduction zones where the denser oceanic plate descends under the lighter continental plate. This has created the Ring of Fire--a circum-Pacific belt of numerous volcanic eruptions and earthquakes. Almost 80 percent of tsunamis in the world take place in the Pacific Ocean. However, there are subduction zones in the Indian Ocean and in the Caribbean Sea too; these regions are prone to earthquakes and tsunamis as well. Destructive tsunamis are usually generated by undersea earthquakes with magnitudes exceeding 7 on the Richter scale.

 Currently scientists cannot predict exactly when an earthquake will occur. However, we know where earthquakes mostly take place on Earth. In addition, the time lapse between the occurrence of an undersea earthquake and the tsunami waves hitting land gives a window of opportunity to evacuate people from hazard zones.

Since 1997, a new type of tsunami warning device has been developed that consists of a pressure sensor placed on the ocean floor, and a surface "buoy" that transmits the pressure readings to a U.S. weather satellite named GEOS. This modern system is called DART (Deep-ocean Assessment and Reporting of Tsunamis).

 While international and national programs are crucial to mitigate tsunami hazards, communities and individuals living in coastal areas or on islands prone to tsunamis can equally play an important role. Some useful tips are:                -- Learn tsunami facts and recognize tsunami warning signs;                -- Be familiar with your environment and community;                -- Participate in activities related to tsunami preparations and emergency plans in your family, school, workplace, religious congregation, etc.                -- If there is a large earthquake, get the latest information from a radio or TV;                -- If you are near the ocean and the ground shakes, evacuate at once;                -- When there is a tsunami warning, never go to the beach to watch the tsunami;                -- Remember the highest ground or the farthest place from the beach is the safest when a tsunami strikes.