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Indian Ocean's Tsunami Early Warning System Taking Shape

Lori Valigra
for National Geographic News
December 23, 2005
 
One year after the Indian Ocean tsunami killed an estimated 300,000 people, progress has been made on setting up basic early warning systems in the region.

A full-blown regional system, however, may be years away, despite predictions that another huge wave could strike at any time.

When the tsunami struck on December 26, 2004, the Indian Ocean had no early warning system to speak of—at least nothing like the Pacific Ocean's array of tide gauges, seismometers, deep ocean sensors, high-tech buoys, and communication systems.

The Pacific system's seismometers happened to detect the Indian Ocean earthquake that created the tsunami.

"We had seismic signals," Charles McCreery said. "But we had no sea-level data to detect or measure the tsunami and no system for disseminating a warning." McCreery is the director of the U.S. government's Pacific Tsunami Warning Center (PTWC) in Ewa Beach, Hawaii.

The PTWC, along with the Japan Meteorological Agency, coordinates the Pacific tsunami-warning system.

The PTWC and the Japanese agency get data instantly from a hundred coastal tide gauges, more than a hundred seismographs (which monitor ground movement), and 11 DART (Deep-ocean Assessment and Reporting of Tsunamis) buoys. The buoys relay water-pressure data from "tsunameters" on the seafloor to monitoring centers.

No such system of sea-level gauges or buoys existed in the Indian Ocean last December.

Interim Solution

Immediately after the tsunami, scientists, politicians, and other citizens from 26 Indian Ocean countries—including Indonesia, India, Sri Lanka, and Australia—began to collaborate on an early warning system and procedures that could save lives.

Though the so-called Indian Ocean Tsunami Warning and Mitigation System will not be fully implemented for years, an interim system is in place.

The PTWC and Japan Meteorological Agency play a key role in the interim international warning system.

The two agencies supply advisories to national monitoring centers—many of them newly established—about huge earthquakes that might trigger tsunamis. The estimated lag time between a quake and its advisory is 10 to 20 minutes.

Almost all of the Indian Ocean countries are already set up to receive the advisories, said Laura Kong, director of the International Tsunami Information Centre (ITIC) in Honolulu, Hawaii. The center is part of UNESCO's Intergovernmental Oceanographic Commission (IOC).

The interim system still has no ability to quickly detect exactly where an Indian Ocean quake occurred and whether it sparked a tsunami. For that, more coastal tide gauges, deep ocean sensors, and other instruments are needed.

Tide gauges along affected coasts could measure whether a huge wave has hit a shore and thereby allow authorities to warn localities likely to be hit later.

Toward a Permanent System

Despite the limited capabilities of the interim system, Kong hails the progress made since the 2004 tsunami, citing educational efforts.

"In the past year we've come from zero awareness of what a tsunami is to knowledge by almost all people on the coast of the Indian Ocean," Kong said.

There is still a long way to go before instruments and local disaster plans for a permanent warning system are fully in place. But Kong and others took heart from the recent IOC meeting in Hyderabad, India.

Speaking from Hyderabad, Walter Mooney said, "The countries seem to be moving quickly and cooperating." Mooney is a seismologist at the U.S. Geological Survey's Earthquake Hazards Team in Menlo Park, California.

Simple steps already have been taken. Most countries have educated coastal residents to watch for a tsunami's physical signs (such as the rapidly receding tide that can precede a monster wave) and how to react (seek higher ground, for example).

Mooney said the Indian Ocean warning system will rely mostly on seismic monitoring and coastal tide gauges.

Fifteen tide gauges that send data in real time are already in place around the Indian Ocean, with a total of 26 expected to be operational by mid-June 2006.

The gauges can detect a tsunami as it hits—too late for the immediate area but a possible lifesaver for areas farther away from the epicenter. For example a tsunami detected by a tide gauge in western Sumatra might warn Malaysia or Thailand that a wall of water could be coming their way within an hour.

"People understand that early warnings save lives," Kong said.

Currently scientists have identified about 70 nationally administered seismometers around the Indian Ocean to be part of a core network.

About half of the seismometers already provide data in real time, so they can transmit earthquake tremors via the Internet, phone lines, or satellites. The other half will eventually be upgraded to real-time status.

Eventually 20 or more DART-type buoys may be deployed, but that likely will take several years, and they are not an absolute requirement for a tsunami warning system, Mooney says.

In the meantime some countries are moving ahead faster on their own.

Malaysia has put the equivalent of five million U.S. dollars into upgrading its automatic earthquake location and alert system with text messaging. The country also has an experimental offshore deep-ocean buoy and sensor system.

And Indonesia, considered a hot spot for future large quakes and tsunamis, has benefited from a 45-million-euro (53.3-million-U.S.-dollar) contribution from Germany to help build its local tsunami warning system.

Two German DART-type buoys are being tested near Indonesia. Ten of the buoys are eventually to be installed off Indonesia between Banda Aceh and Bali over the next three years, along with seismometers and coastal tide gauges.

Kong estimates that the buoys cost up to U.S. $300,000 to deploy and $50,000 a year to maintain. By contrast, a good tide station can cost less than $50,000 to establish and only a few thousand dollars in annual maintenance—an important consideration for developing countries.

More Tsunamis Ahead

Scientists expect another deadly tsunami to happen again in the Indian Ocean or even off the U.S. Pacific Northwest coast, which has characteristics similar to the area where last year's disaster was centered.

The only question is when: It could be tomorrow or in a few hundred years.

"In the Indian Ocean area everyone has stepped up their procedures in governments to better monitor potential tsunamis," Kong said.

"They're increasing their preparedness and education to make sure that when they do receive a warning, they have emergency response plans."

Kong said several nations have conducted practice drills. The western U.S. already is reasonably prepared, said Stéphan Grilli, chair of the department of ocean engineering at the University of Rhode Island in Narragansett.

Grilli is working at the forefront of the newest wave in tsunami research: computer modeling and simulations. He was part of a team of 25 scientists who in May took a boatload of instruments to study the deep sea where the Asian quake and tsunami originated.

Their goal was not only to try to discover what had happened but also to use that information to predict what might happen in the future from as many scenarios as possible.

Grilli is enthusiastic about the potential of computer models to help communities plan for disaster.

"If we get the water pressure [available from DART-type buoys], we can estimate the height, and the depth of the wave gives us the speed," he said.

"So with modeling we could be able to tell that, if 80 percent of a city is hit by a 30-foot [9-meter] wave, there could be other places for people to escape."

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