Waiting and Waiting For the Next Killer Wave

A tsunami alarm for the Indian Ocean may be worth the cost, but can it retain public support over the long haul?

4 min read

The tsunami that killed 230 000 people in 11 countries was foreseen by Thailand's chief meteorologist, but no one listened. Now his country has put him in charge of tsunami awareness. The United Nations working group on disaster reduction advocated building a tsunami early-warning system in the Indian Ocean, but nothing happened. Now the United Nations wants to put one together in a year.

There's nothing like disaster to concentrate the mind. Then again, there's nothing like metronomic, decades-long boredom to lull it back to complacency. Judging from the seismic history of the Indian Ocean, a warning system would surely pay, but the payoff would be seen only after a lifetime. Meanwhile, can the poor countries of the region, resolving early this year to put such a system in place, maintain the willpower to keep on paying for it?

Going down: This sensor will sit on the Pacific Ocean's floor, detect variations in water pressure, and relay the data to tsunami warning centers. Such sensors will soon be put in the Indian Ocean.

"The cost would be about US $20 million a year, or $2 billion for 100 years, which sounds like a bargain," says Albin J. Gasiewski, president of the IEEE Geoscience and Remote Sensing Society. "For this one event, the world community has already ponied up that amount in relief; if you could cut loss of life in half, you'd pay for this system with one event in a hundred years."

Yet the world has little experience managing risk over the long haul, admits Gasiewski, who also heads microwave systems development at the National Oceanic and Atmospheric Administration's laboratory in Boulder, Colo. He notes that all long-term U.S. plans�notably those to protect national security�evolved over decades, in response to a string of threats. It took many scares over the course of half a century to coax the nations of the Pacific Ocean to build their tsunami warning network. But tsunamis are 2 percent as likely in the Indian Ocean, and the nations there will find it harder to maintain their resolve.

"It will be like in those Maytag commercials, where the repairman waits and waits for someone to call," says Michael Glanz, senior scientist at the National Center for Atmospheric Research, also in Boulder. "Every country, even the United States, moans and groans about the money for tsunami warning systems."

The Pacific warning system ties together two elements: a surveillance network of seismic sensors, tide gauges, and satellites�and detailed maps of the ocean floor. Together they enable scientists to predict how hard a given tsunami will hit a given target's shores. Neither the monitoring nor the mapping has gone very far in the Indian Ocean.

It would be relatively easy, however, to exploit one idea that was applied only recently in the Pacific: the deep-sea sensor. Each one can detect a rise of as little as 3 centimeters in the kilometers-high column of water above it. The sensor sends the information as acoustic chirps to a buoy on the surface, which then relays it via satellite to tsunami warning centers.

Working together, the sensors look for a tsunami's signature�a wave speed of around 430 knots, a wave front up to thousands of kilometers long, and an amplitude, in the open ocean, of a meter or less. The chirps normally come at long intervals, to stretch battery life up to four years; when tsunamis threaten, the chirp rate rises.

In November 2003, just a month after the sensors went into full operation, they correctly predicted that a tsunami threatening Hawaii would hit its coast with just a half-meter-high wave. The prediction is credited with saving the state a coastal evacuation that would have cost an estimated $68 million�not bad for a system that then numbered six sensor-buoy links, each costing $250 000.

In January, the Bush administration said it would put 26 more sensors in the Pacific, the Caribbean, and other waters near U.S. shores.

Perhaps half a dozen of them could cover the Indian Ocean. "You'd need about 50 more to blanket the earth," says Chris Meinig, head of the engineering group that designed the sensors at the Pacific Marine Environmental Laboratory, in Seattle. "You might even deploy one quickly, from an airplane, to avoid panics due to earthquakes and aftershocks."

The most tantalizing development is satellite surveillance. The recent tsunami was the first ever to be detected from on high (albeit days after the fact), by radar altimetry from satellites jointly operated by the space agencies of the United States and France. "They couldn't do it in real time, and the satellites aren't over the ocean continuously," Meinig notes. "But it's certainly technology that's going to be looked at."

This can-do program makes sense for rich countries, which have the organizational resources to exploit every minute of extra warning time. In Hawaii and Japan, for instance, disaster management professionals work out ways to warn and evacuate populations; signs along the shore and in the front pages of telephone books repeat the mantra of tsunami readiness; children are trained, and evacuation drills continually test the system's efficacy. But the countries that were just devastated largely lack these capabilities and so cannot make such effective use of the warning time a high-tech system might provide.

There may be a way out. International agencies could fashion a system that would give tsunami watchdogs more to watch for, preventing boredom on their part and stinginess on the part of their governments. "We could make the buoys work on multihazard problems," says Meinig. "They could measure the top few hundred meters of water for salinity and so forth, to help meteorologists predict monsoons and cyclones. In the Pacific, we can predict El Niño�we predicted the mudslides California is getting months ago."

Alarm bells that rang every few years would be kept shiny and new for the next great tsunami, even if it strikes after everyone now alive is dead.

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