PMEL / NOAA
A false-color virtual globe, centered on the Pacific Ocean, shows the propagation of tsunami waves from their seismic source off the coast of Japan on March 11, 2011. Black, purple and red denote the highest waves.
By Alan Boyle
Last year's earthquake and tsunami was a catastrophe for Japan ? but a problem averted for Hawaii and the U.S. West Coast, partly due to luck and partly due to the success of long-range tsunami tracking. Now researchers are working to bring that success closer to home.
If a similar ocean wave were to target the U.S. coastline in the future ? and seismologists say that's only a matter of time ? the emergency response should be much improved, thanks to the lessons learned from last March's super-tsunami.
"Definitely there are a lot of lessons learned from a big event like that," Vasily Titov, director of the National Oceanic and Atmospheric Administration's Center for Tsunami Research, told me this week.
Titov and his colleagues, who are based at the Pacific Marine Environmental Laboratory in Seattle, have focused for years on building better computer models to predict how tsunami waves will spread out from an undersea seismic shock like the one that rocked Japan. Tsunami trackers came in for a good deal of criticism after the 2004 Indian Ocean earthquake and tsunami, which killed an estimated 230,000 people in 12 nations. Since then, government agencies have worked together to fill in the gaps in an oceanwide network of deep-sea and surface-buoy sensors ? and the upgrades paid off big time last year.
Readings from a network of more than 50 buoys ? including the federal governnment's Deep-ocean Assessment and Reporting of Tsunamis system, or DART ?tracked wave heights after a magnitude-9.0 shift in the ocean floor set off a giant wall of water. The waves rose as much as 6 feet in open ocean. "Ten years ago, people would say, 'Oh, it's not possible to have a tsunami that high,'" Titov said. "That was the event that I was hoping not to see in my life."
The computer model correctly predicted the level of flooding that Hawaii would face, seven hours after the earthquake. That provided enough time for a proper evacuation. "Deaths were avoided in Hawaii ? I'm pretty confident about that," Titov said.
The model also showed that there'd be only minor impact on the West Coast, due to the fact that the tsunami wave arrived at low tide. "If the West Coast had high tide during tsunami, it would have been much different," Titov said. "There would have been flooding all over the place."
NOAA's Eddie Bernard narrates a video showing how the Honshu tsunami propagated outward from its center off the coast of Japan on March 11, 2011.
The next wave?
Titov happens to be headquartered in a region that could become ground zero for a future Japan-style tsunami. Studies have indicated that the Cascadia subduction zone, off the coast of Washington state, Oregon and British Columbia, is capable of generating the same kind of ocean wave. In fact, it's thought that such a shock took place off the West Coast more than 300 years ago, setting off a tsunami wave that reached all the way to Japan.
Concerns about the next big wave, wherever it may come, is driving international efforts to track tsunami phenomena closer to the source. Last year's quake and tsunami killed nearly 16,000 people, with many of those deaths coming along the coast. If Japanese authorities had had a quicker assessment of the tsunami threat, they might have launched more intensive evacuation efforts in the first half-hour after the earthquake was detected. Thousands more lives might have been saved.
"That has become the main challenge," Titov told me. "What can be done for this type of event?"
To get a better grip on the local effects of a tsunami, a different kind of monitoring system is needed ? a system that has scores of interconnected sea-floor stations, situated close to the source of a potential tsunami shift. The stations would have to be equipped with seismometers and pressure gauges, and send real-time data via satellite links for sophisticated analysis.
Titov and his colleagues think they have come up with a solution to the challenge. "The system we developed worked better than expected," he said. "Detectors can be placed much closer to the source."
Now Japan is making plans to deploy a new $400 million network of 154 sensor stations straddling the Japan Trench, which was the source of last year's seismic shock. That network is due to be put into place in the 2014-2015 time frame. Meanwhile, NOAA is planning to move some of its DART buoys closer to the Cascadia subduction zone and other seismic hot spots.
Simulations suggest that the sensor system and upgraded analysis software can deliver an accurate assessment of local flooding in 30 minutes or less. That might still require authorities to go ahead with pre-emptive evacuations in some areas, even if the initial tsunami alert turns out to be a false alarm. "While the timing is challenging, the situation is manageable," Titov said.
Maintaining the network
At the same time, the existing network of tsunami-tracking buoys needs to be maintained. One of the problems that came to light after the 2004 tsunami was that some of the buoys in the DART network were prone to failure. One critic complained that the tsunami monitoring system was like "a fire alarm that cannot ring."
"The problem is that even that strong array is budgetarily difficult to maintain," Titov said. "That has become the main challenge. We're trying to figure out how to maintain it."
Titov said he found it hard to believe that it's already been a year since that horrible day?? March 11, 2011, which is known as "3-11" in Japan. "My heart goes out to all the Japanese," he said. "A lot of our colleagues are from Japan. This has become very personal."
That personal perspective sharpens Titov's desire to develop faster, better ways to predict the paths of the giant waves to come.
"The fact that it's been a year already makes me a little nervous," he told me. "I want to move fast with this research so we're ready for the next tsunami."
More about the Japan quake anniversary:
For more about the future of tsunami forecasting, check out Richard Monastersky's report in the journal Nature.
Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.
Source: http://cosmiclog.msnbc.msn.com/_news/2012/03/08/10613522-the-next-wave-in-tsunami-science
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