TSUNAMI -The Killer Waves

satelliete view of tsunami

Tsunami waves, which hit India for the first time on 26th December 2004 wreaking havoc across the southern coastline, are a known phenomenon in the pacific ocean region,which stretches from chile in Latin America to Japan in East Asia.

The waves are usually triggered by seismic distrubances-costal earthquakes, volcanic eruptions or undersea landslides-that jolt the ocean floor. Tremors under the sea displace ground surface, sending the water rapidly outward in concentric circles from epicenter. The result is a deep wave, stretching from the sea's surface to the floor that travels horiantally at speeds up to 500 miles per hour and reaches heights of 50 to 100 feet.

The waves travel faster in deep water,rising further as they approach shore.In open sea,tsunamis are only about a meter high,but when they reach a shoreline they can be taller as a home and weigh millions of tonnes.Though the bottom of the wave is slowed down by the sharp elevation of the ocean floor near the coast, its top part keeps moving at the original speed. As a result, vast quality of water piles up and finally crashing over the shore with the amazing force, thus causing the massive destruction.

The first sign of an approaching tsunami is the sea tide receding from the shore, which leaves the large part of the sea floor exposed. The ocean water then flows towards the shore faster than before, resulting in high waves. This phenomenon is repeated several times before tsunami itself hits the land.

The tsunamis can travel long distance without losing the original power.Neither islands nor reefs diminish their speed or power. Usually the waves do not dissipiate until they strike a continental landmass, and some waves travel back and forth across the ocean for a week.

Japan is one of the two Asian countries - the other being Indonesia - to be frequently hit by Tsunami waves. In fact the word tsunami is derived from the japanese language to describe very long, low seismic sea waves.

Fortunately, the tsunamis of a serious nature are known to occur only once in a decade in the region. But when they occur, they leave a trail of destruction, causing heavy damage to the life and property. One of the most destructive tsunami was in July 1998 that struck Papua New Guinea's north coast an the one generated off the coast of Chile in 1960 caused havoc over large distances. Hundreds of people die when a huge wave travelling at a speed of 750 km per hour smashed japan in 1960, following a series of quakes in Chile on the other side of the Pacific Ocean.