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On Dec 26, 2004, a huge earthquake took place off
the northwest coast of the Indonesian island of Sumatra,
under the Indian Ocean. The earthquake, 9.0 in
magnitude, was the most powerful one to shake the earth
in 40 years. As a result of this massive earthquake,
huge waves formed in the ocean. These waves rushed
across the ocean in all directions, towards the coastal
areas bordering it. They traveled at speeds of up to
480 kilometers per hour. Within 75 minutes, they had hit
places as far as 600 km away, such as the coast of
Africa; and were even detected on the East Coast of the
United States. Eleven countries were affected by these
giant waves. Hardest hit were Indonesia (particularly
the province of Aceh), Sri Lanka, India, Thailand, and
the Maldives. More than 300,000 people died from the
disaster, half a million were injured, thousands still
remain missing, and millions were left homeless.
Billions of dollars worth of property was lost due to
this natural disaster. Entire cities were destroyed:
public and private buildings, airports, roads and
bridges were swept away by the water; farmland was
flooded, livestock killed and forests were mowed down.
Even the fish in the seas and rivers were destroyed due
to the pollution of the water. People who were not
drowned by the waters faced starvation as supplies could
not be rushed to them in time. There was also the danger
of diseases spreading rapidly, as the water supplies
were contaminated. In some countries, the land was
completely uninhabitable. In the Maldives, for example,
the waves left 14 of the archipelago's islands
uninhabitable, requiring its inhabitants to be
permanently evacuated, and another 79 islands without
safe drinking water. Scientists have a special name
for these destructive waves. They call them by the
Japanese name tsunami. Represented by two
characters, the top character, "tsu," means "harbor",
while the bottom character, "nami," means "wave." In the
past, tsunamis were sometimes referred to as
"tidal waves" by the general public. However, the term
"tidal wave" is misleading because tsunamis are
unrelated tot he tides. Tides result from the
gravitational influences of the moon, sun, and planets,
whereas tsunamis are caused by disturbances that take
place on the ocean floor. These disturbances would
include underwater volcanic eruptions, landslides, or
even a meteor landing on the ocean and crashing on to
the ocean floor, or, most common, an underwater
earthquake. The disturbance on the ocean floor
produces a shock wave that travels through the water,
just as a loud sound travels through the air. At the
same time, it also may cause the ocean floor to shift
and slide. It is the shifting and sliding motion an the
shock wave that creates the ocean waves. As soon as the
earthquake occurs, the waves of water begin to travel in
all directions from the area of disturbance. The waves
build up in size and speed as they move towards the
shore. As the waves approach the shallow waters along
the coast, they grow to an even greater height. They can
be as high as 100 feet. However, oddly, when a tsunami
approaches land, the first sin is a swell or rise that
looks very much like an ordinary wave. then the sea
level falls for a number of minutes, as if it were very
low tide. A big area of the ocean floor near the coast
may be exposed. Then, the great walls of water come
crashing in ! |
