[Marinir] [SPIEGELnet] A TSUNAMI REPEAT
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December 23, 2005
A TSUNAMI REPEAT
Researchers Warn of More Quakes in Southeast Asia
By Axel Bojanowski
The Dec. 26 earthquake and tsunami triggered a massive research effort to
better understand the geology of the region. What researchers found is
daunting. The fault line which produced the tsunami, remains under extreme
tension. Another severe earthquake could come at any time.
The death toll on Dec. 26, 2004 was horrifying. Some 230,000 people around
the Indian Ocean basin died as a result of the devastating tsunami that hit
the coasts of Indonesia, Thailand, Sri Lanka and India among other
countries. Soon afterwards, governments and organizations across the region
and around the world pledged to create a tsunami early warning system. But
what they can't do is prevent further, violent quakes in the region. And
such quakes, say a number of research teams investigating independently of
each other, are likely to come sooner rather than later.
Sonar images of the ocean floor off Indonesia -- taken by the Leibniz
Institute of Marine Sciences at the University of Kiel -- have given
researchers cause for disquiet. The images, created by Wilhelm Weinrebe and
his team of scientists, take a closer look at the sea floor near Sumatra,
some 5,000 meters (16,400 feet) down. The Australian Plate dives beneath the
continental shelf here, creating incredible tension as the two rock masses
rub against one another. And recently, according to the researchers from
Kiel, the pressure hasn't dissipated one bit; they found no evidence
whatsoever of any large tremors in the recent past. In other words, a
violent earthquake deep below the ocean is overdue.
SONAR IMAGES: WATCHING AN EARTHQUAKE BREWING
Click on a picture to launch the image gallery (6 Photos).
The Kiel team aren't the only ones concerned. Geologist Kerry Sieh from the
California Institute of Technology is likewise worried about a repeat of the
tsunami catastrophe. In recent months, he has examined kilometers of coral
reefs off the coast of Indonesia. His conclusions? He discovered that the
Dec. 26 earthquake -- and the large quake on March 28, 2005 -- ripped open
the border between the two continental plates like a zipper. But only a
quarter of the border's length was affected. South of the two earthquakes'
epicenters, there hasn't been a powerful quake for centuries.
In other words, says Sieh, the bedrock is strained to the breaking point.
And the two recent quakes served to increase the pressure even further -- by
the equivalent of 50 years worth of plate movement. The "earthquake clock"
thus took a great leap forward -- toward another devastating quake according
to Sieh. He says it won't be much longer.
Unparalleled research campaign
Last year's violent tsunami unleashed death and destruction on a massive
scale, but it also unleashed an almost unparalleled research campaign. At a
moments notice, research ships like the German ship "Sonne" or the American
ship "Performer" -- ships that are normally booked out for years at a
time -- were suddenly freed up for projects in the region. For months,
researchers criss-crossed the ocean near the quake's epicenter examining the
ocean floor far below.
SATELLITE IMAGES: THE DESTRUCTION OF THE TSUNAMI
Click on a picture to launch the image gallery (6 Photos).
In minute detail, they were able to reconstruct exactly what happened below
the earth off the coast of Sumatra on that fateful Sunday. Two thick plates
of rock, each dozens of kilometers thick, rub against each other there --
and often they stick, creating enormous tension. Earthquakes are, for the
two plates, the geo-tectonic equivalent of a sneeze and release the built up
pressure. On Dec. 26, 2004 at 1:58 a.m. Central European Time, the South
Asian Plate couldn't withstand the tension any longer: an edge of the plate
broke off and the rest of the plate jerked upwards. With a magnitude of 9.3,
it was the strongest earthquake anywhere in the world in the last 40 years.
>From the northern tip of Sumatra, a 1,300 kilometer long rip in the Earth's
surface suddenly appeared. The 160-kilometer-deep gash raced northwards at a
speed of 2.5 kilometers per second, and the ocean floor instantly raised 15
meters. The thrust created the monster tsunami -- a wave which caused
terrible damage even thousands of kilometers away.
The tremors shook the entire globe. Like a rug being shaken out, Sri Lanka
rose and fell fully nine centimeters. A number of islands were shifted
dozens of centimeters -- the entire Indian subcontinent moved east by two
centimeters. Weeks after the quake, the entire Earth was still vibrating.
Best alarm system in the world.
The new research, which seems to indicate that the catastrophe could soon
repeat itself, has added renewed urgency to the creation of a tsunami early
warning system in the Indian Ocean. The system is to be constructed by a
German team, though earthquake research in Germany was hardly a major area
of research before last year. Now, though, a number of institutes are
involved in the project and have been funded by the German government to the
tune of ?45 million.
Japan and the United States, both experienced with tsunamis and tsunami
research, were also interested in developing the early warning system for
the Indian Ocean. When they were not awarded the project, they became
reluctant to share their expertise and data with the Germans. In any case,
US researchers found the plan to develop a modern early warning system
within just three years to be unrealistic. Undeterred, the German group, led
by Jörn Lauterjung from the National Research Centre for Geosciences located
in Potsdam, said they planned to build the best alarm system in the world.
But nobody quite knew how it was to be done.
But that changed. In countless meetings, described by participants as
"chaotic and creative," the concept took shape. Faster than anticipated,
they found qualified engineering firms to build the necessary equipment.
The basis of the warning system is a network of Richter scales, or
earthquake measuring devices. They're important, because most tsunamis are
caused by quakes on the ocean floor. The more seismometers placed in a
region, the faster and more accurate the readings for locating a quake --
and in a tsunami-warning system, every second counts.
The Indian Ocean tsunami early warning system.
The Indian Ocean is still too crudely outfitted with seismographs to give
accurate, on-time warnings, which is the reason 40 machines with uplinks to
satellites will be installed in the region. Within 2 minutes the strength of
a sea-floor quake can be measured, Lauterjung promises. The first
seismographs are already being installed.
Predicting future tsunamis
One important element of the warning system is a network of buoys that sense
dangerous fluctuations in the ocean surface. Two German test-buoys dance on
the waves already, about 160 kilometers from the Sumatran coast.
Clearly impressed by the progress of the Germans, the US experts gave in.
Last August they released their data and agreed to cooperate. Ships from
both nations explored the bottom of the Indian Ocean and fed the maps in
computer models intended to predict the course of future tsunamis. It was an
ambitious enterprise, and the Americans have puzzled for nine years on
similar programs for their Pacific Coast -- so far without breakthrough
>From the intensive research after the tsunami catastrophe, other coasts
emerged as endangered. The Atlantic and the Mediterranean also needed better
protection. If political conflicts made work in the Indian Ocean nations
difficult, cooperation was easier along the Atlantic and Mediterranean
coasts. They'll have cooperative alarm systems ready by the end of 2007.
If another massive earthquake and tsunami hit Asia, though, even the best
warning system wouldn't save everybody in the affected region. The city of
Padang, with its almost 1 million residents, for example, lies just north of
the earthquake zone. Following a large quake under the ocean, a tsunami
could reach the city -- some of which lies below sea level -- within
When the Dec. 26 tsunami struck the Indonesian town of Banda Aceh, it flowed
up to eight kilometers inland and killed tens of thousands of residents.
Padang has three times as many people as Banda Aceh and fully half of them
live fewer than five kilometers from the coastline. Were a major tsunami to
hit the city, the American geologist Sieh fears, the death toll could end up
much higher than the 169,000 who lost their lives in the Banda Aceh region
late last year.
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