This is SCIENCE IN THE NEWS in VOA Special English. I'm Bob Doughty.
I'm Shirley Griffith. Our subject this
week is tsunamis -- the sea waves often caused by earthquakes.
Our broadcast today begins a few years ago on a beautiful
day in Thailand.
schoolgirl, Tilly Smith, was spending the day at Maikhao Beach in Phuket. Then Tilly saw that the water seemed to have
disappeared from the beach. When she
looked out to sea, the surface of the water looked strange.
ten-year-old girl warned her parents. They warned others. People moved
away from the water, saving themselves from almost sure drowning. Tilly had recognized the signs of a tsunami. She had studied tsunamis at school.
young girl had witnessed a part of the historic tsunami of December twenty-sixth,
two thousand four. In Thailand, some waves
were as high as many buildings. The walls
of water also struck a number of other nations, and killed more than two
hundred thirty thousand people.
incident produced a major effect on many countries. It has also led to actions to protect against
people say tsunamis are tidal waves. But
tides are the ebb and flow of saltwater against the coast. Tsunamis are not normal tides. Instead, extreme events cause unnatural actions
to form tsunamis. Scientists blame strong
earthquakes for eighty to ninety percent of tsunamis. Other causes are landslides and underwater or
nuclear explosions at sea. Still another
is the crash of large asteroids, minor planets that fall to earth.
tsunami is not just one wave, but a series of waves. Some of the waves can be huge.
Some scientists say the earthquake that caused
the great tsunami of two thousand four measured nine points in intensity. Others say it was nine point three. Whatever the force, it was among the
strongest earthquakes many people could remember. The earthquake created a tsunami that killed
people in eleven countries.
The earthquake of December twenty-sixth took place just east
of the Sunda Trench. The trench is an
extremely deep hole on the floor of the Indian Ocean. It stretches about two thousand six hundred
kilometers along the island of Sumatra. A
tsunami formed near the place where the earthquake began and traveled outward
in all directions.
water reached the northern edge of Sumatra about twenty minutes after the earthquake.
In Aceh Province alone, up to one
hundred seventy thousand unsuspecting people died in a short time. Pictures taken from the air after the tsunami
also showed a shocking loss of land.
all over the world reacted to the killer tsunami. They gave large amounts of money to help the
victims. But they also made plans to
protect against other terrible waves.
built or improved existing walls and floodgates to block the waves. And they worked to create or improve tsunami
warning systems. Such a system contains
sensing equipment that notes danger. The
system also operates the processes for spreading warnings to threatened
Some countries, like Japan, already had good
warning systems. Earthquakes often
strike Japan. Some earthquakes cause
tsunamis. Japan has suffered hundreds of
tsunami waves over the years. For
example, the Great Tsunami in nineteen thirty three killed more than three
thousand people. But some tsunami waves
were small, and looked just like normal waves.
The United Nations agency UNESCO created the
Intergovernmental Oceanic Commission, or I.O.C., in nineteen sixty. This organization has tsunami warning systems
in many places. It supervised creation of
a system for nations on the edges of the Indian Ocean after the great earthquake
and tsunami of two thousand four.
Twenty-five stations watch for possible
earthquake activity. The stations
provide information to many national tsunami information centers and several deep
ocean sensors. The I.O.C. says its
efforts are the beginning of a worldwide tsunami-warning program.
disasters in the Indian Ocean made Indonesia decide it must have a warning
system of its own. In two thousand five,
almost one thousand people were killed in an earthquake near the island of Nias. But the earthquake did not create a tsunami. Still another tsunami took place after an
earthquake near Java in two thousand six. That tsunami was not nearly as severe as the one in two thousand four. But it still killed hundreds of people.
year, a tsunami warning system began operating especially for Indonesia. The system probably will be completed by two
new system is called the German-Indonesian Tsunami Early Warning System, or GITEWS. It has been busy recording earthquakes that
could produce huge waves. On February
eleventh, GITEWS reported a seven point three earthquake in Indonesia's Talaud
Islands near Sulawesi. But no tsunami
is a joint project of Indonesia and the German government. Germany's national research center for
geosciences organized the project. Germany,
Indonesia and other partners helped make it financially possible.
Helmholtz Association of German Research Centres described new methods and technologies
in the new warning system. The group
says less time passes for an earthquake shock wave to reach a measuring
instrument than in the past. But it is
difficult to read and judge a wave when it is near.
deal with that problem, the designers developed a special computer software
program. They say the program can show
the source, placement and size of several strong earthquakes within two
example of new methods in GITEWS involves how a tsunami behaves. A tsunami travels hundreds of kilometers per
hour in deep water. But it slows down in
water that is not deep. In coastal areas
it can swell, or enlarge, to waves of up to thirty meters high.
To save lives, a tsunami must be
recognized as such before it can reach land. GITEWS provides nine new measuring stations in the Indian Ocean. That means Indonesia is not the only nation
to receive the information. The system
also can help other countries.
and mechanical systems are also responsible for getting the news of huge waves
to threatened areas. Local officials are
responsible for broadcasting warnings as fast as they can, by any method they
Indian Ocean tsunami of two thousand four was among the worst that ever
happened. But the Pacific Ocean area has
experienced more of the deadly waves.
Experts estimate sixty percent of tsunamis take place there. The Pacific Tsunami Warning Center watches
for earthquake activity that could cause tsunamis.
National Weather Service is an agency of the National Oceanic and Atmospheric
Administration, or NOAA. Its experts
serve as part of the Pacific Tsunami Warning System. They also keep watch on the American state of
Hawaii from an operations center near Honolulu.
suffered major tsunamis during the twentieth century. In nineteen sixty, the Great Chilean
Earthquake caused waves that took many lives. That tsunami almost completely destroyed the city of Hilo.
month, eighteen South Pacific countries sent representatives to a tsunami
meeting in Samoa. Many expert observers
also attended. Those taking part
discussed the results of an exercise throughout the Pacific area last October. The exercise tested warning and emergency communications
and national and local readiness.
National Weather Service center in Palmer, Alaska supervises a warning station for
the United States mainland and Canada.
January of two thousand seven, Canada increased its protection. It opened the Canadian Atlantic Tsunami Warning
System. The system was designed to especially
protect the nation's Atlantic Ocean coast and the Gulf of Saint Lawrence. Canada's national government, five easternmost
provinces and NOAA cooperated in the project.
This SCIENCE IN THE NEWS
was written by Jerilyn Watson. Brianna Blake was our producer. I'm Shirley Griffith.
And I'm Bob Doughty. Join us again next week for more news about science in Special English
on the Voice of America.