The warnings are few. The signs are sudden. The tide goes in the reverse. A thunderous roar fills the air. And then it strikes. And when it is over, nothing is left. A tsunami. The word in Japanese means
‘harbour wave’. Japan has been hit by many tsunamis
in its history as a result of its location. It lies across the edges of
four tectonic plates, where most earthquakes, the principal
cause of tsunamis are born. When two tectonic plates push together
the resulting earthquake sends an enormous burst of energy
up through the ocean, displacing enormous quantities of water. A series of waves expands
in all directions. In deep water these waves travel fast,
up to five hundred miles an hour, but only reach a height of a few feet. A passing ship might not even notice. But as the waves enter shallow waters, friction with the ocean floor
lowers the wave speed and raises their height, until at landfall
they can engulf a ten-story building. Unlike ordinary waves a tsunami wave
doesn’t crest and break. Instead, it advances like a wall of water
that crashes over the coastline and everything in its wake
reaching even as far as a mile inland. More damage is caused
when the wave recedes dragging everything in
it back underwater. And most tsunamis have
multiple waves, each arriving anywhere from ten to sixty
minutes after the first strike, just when survivors think
the danger is over. The deadliest tsunami ever recorded
occurred in December 2004. An earthquake off the coast of Indonesia triggered a tsunami that
surged across the Indian Ocean and reached as far as the coast of Africa. Whole sections of cities were destroyed. More than 200.000 people died. Most had no way of being warned. Five thousand miles away the Pacific
Tsunami Warning Center in Honolulu is on call twenty-four
hours a day to prevent a similar tragedy from happening
in the United States. Scientists monitor tremors and quakes
from around the globe If a quake big enough to cause
a tsunami occurs, it is their job to alert the coastlines
in the tsunami’s path. The advice is simple:
‘Move to higher ground, wait for news that the
tsunami has passed and be ready to deal with
the ruins left in its wake.’

Leave a Reply

Your email address will not be published. Required fields are marked *