Getting word out a challenge in tsunami warnings
System for Indian Ocean would require reaching remote areas
By Michael Coren
(CNN) -- The tsunamis that struck after an earthquake under the Indian Ocean took the world by surprise, but the killer waves could have been tracked almost from their birth if warning systems were in place, according to scientists.
The proper equipment -- buoys, seismic stations and satellites -- may have bought enough time to evacuate some coastlines.
Such a network may become a reality in the wake of the December 26 disaster that killed more than 155,000 people.
"What's envisioned for the Indian Ocean is a new tsunami warning system," said Harold Mofjeld, senior scientist with the National Oceanic and Atmospheric Administration's tsunami research program in Seattle, Washington.
"They need warning centers, computer modeling, people educated in evaluating information and infrastructure to allow the information to get to people on the beach."
However, the greatest challenge in protecting people from tsunamis may be getting the word out. No one has devised an effective way to warn millions of people in areas like Southeast Asia -- many without modern communications -- to abandon their homes and cities at a moment's notice.
"I think it would be a massive undertaking to actually have a full-fledged tsunami warning system that would really be effective in many of these places," said Jan Egeland, a U.N. emergency relief coordinator.
"The problem with tsunamis is that it takes hours -- or minutes -- for this wall of water to come, and there's just very, very little time."
The science of predicting tsunamis does not guarantee protection from them. Since the massive waves may travel at speeds exceeding 500 mph over deep water, there is scant time for scientists to interpret data from tidal gauges, seismographs and buoys. The need for prompt warnings leaves little margin for error.
"The basic criteria is to get a warning out ... within 10 and 20 minutes," Mofjeld said.
In the past, this urgency has led to false alarms, which dilutes the effectiveness of subsequent warnings. In fact, NOAA reported that 75 percent of all tsunami warnings since 1948 have been false.
Pacific system a likely model
Nevertheless, a tsunami early warning network proposed by India may be ready for operation within two years.
The network of buoys and seismic stations likely will be modeled off the Tsunami Warning System that has been deployed in the Pacific Ocean for decades.
Such a system was backed at an international summit Thursday in Jakarta, Indonesia, aimed at helping nations rebuild after last month's massive waves struck beaches from South Asia to East Africa.
Since tsunamis battered the coastlines of the United States and Japan in the 1960s, an international effort to establish the Tsunami Warning System was formalized in 1965. Hundreds of seismic stations, coastal tide gauges and deep-water buoys were built and now detect Pacific tsunamis affecting the network's 26 member nations.
The DART program, or Deep-ocean Assessment and Reporting of Tsunamis, deployed six buoys in the Pacific from Alaska to the equator. These sensors are anchored in deep water -- five in the North Pacific and one in the South Pacific -- to sense the killer waves.
Each buoy consists of two parts: a pressure sensor anchored to the sea floor and a surface transmitter. The pressure sensor can measure a rise in sea level just a centimeter above normal, indicative of a passing tsunami wave. This data then is transmitted acoustically to a surface buoy and relayed by satellite to warning stations in Hawaii and the Pacific Northwest.
Costal tide gauges also detect local changes in sea level. Scientists must use diverse resources such as ocean buoys, earthquake readings and, increasingly, computer modeling, to issue warnings and evacuation orders.
The problem with tsunamis is that it takes hours -- or minutes -- for this wall of water to come, and there's just very, very little time.
-- Jan Egeland, a U.N. emergency relief coordinator
Yet even in the most active region, the Pacific Ocean, only about six major tsunamis sweep across the entire ocean each century, according to NOAA records.
Since tsunamis are less common in the Indian Ocean, far away from the volcanic "Ring of Fire" tracing the coasts of Japan and the shores of Alaska and South America, there was little concern until the recent disaster.
The cost of ignoring the threat of tsunamis, in the Indian Ocean and perhaps even in the Atlantic Ocean and Caribbean Sea, where no monitoring systems exist, may now be too great.
Network would be expensive
A tsunami warning system for the Indian Ocean will not be cheap.
Each buoy costs about $250,000. The price of maintaining and deploying the whole system would cost far more.
Advances in computer modeling and satellite telemetry mean nations protected by the Indian Ocean system may get more value for their money over previous warning systems. A new generation of sensors and monitoring tools is being developed, promising better accuracy and more timely forecasts.
"The warning systems are in their infancy. We're getting better and better at informing the public," said retired Air Force Brig. Gen. D.L. Johnson, director of the National Weather Service.
Scientists at the Pacific Marine Environmental Laboratory in Seattle are working on an integrated network of earthquake monitors, two-way communicating ocean buoys and computer models that pull together information for instant predictions.
"We're developing a prototype system that will interface tsunami computer simulations with buoy observations and earthquake information to make a forecast at the beach," Mofjeld said. "That will be a step forward."