Developing a Global Tsunami Warning System
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JIM LEHRER: The difficult business of warning people about tsunamis before they strike. It’s a subject that’s been much discussed since the disaster of two weeks ago. Betty Ann Bowser, for our Science Unit, reports on how those systems could work.
BETTY ANN BOWSER: It was just before 3 p.m. at the tsunami warning center in Honolulu last Wednesday. An aftershock from the Sumatran earthquake was detected.
SCIENTIST: It would take about nine.
SCIENTIST: This is – it says five, nine, three stations –
SCIENTIST: That’s right.
BETTY ANN BOWSER: Scientists from the National Oceanic and Atmospheric Administration turned to their computers.
DR. CHARLES McCREERY, Director, Pacific Tsunami Warning Center: We’ve probably responded to 50 earthquakes of this size or bigger over the last week and a half.
And this will continue for a long time. We would start getting concerned about some kind of a — the possibility of a tsunami if the earthquake gets above about magnitude 7.
BETTY ANN BOWSER: The quake turned out to be a small one. But if it had been big, the scientists here would once again have been unable to tell if the quake had triggered a tsunami, because the Indian Ocean has no tsunami detection devices or warning system.
NOAA geophysicist Stuart Weinstein was on duty Christmas Day when he saw that there had been a major earthquake. Colleague Barry Hirshorn raced to the center to join him. Common sense told them there would be a tsunami. But with no measuring equipment in the Indian Ocean, they were unable to detect it. Even worse, they had no idea who to call and warn in the region.
STUART WEINSTEIN, Geophysicist, Pacific Tsunami Warning Center: I think the “holy cow” moment didn’t occur until we started getting the first preliminary reports over the wire services that, in fact, a damaging wave struck Phuket, Thailand and Sri Lanka.
BETTY ANN BOWSER: Were you frustrated?
STUART WEINSTEIN: Very frustrated. Frustrated and to a certain extent humiliated. It’s humiliating for me as a geophysicist working for a tsunami-warning program to learn first of a tsunami from a wire service than from a tide gauge. That — it doesn’t get any worse than that, quite frankly.
BETTY ANN BOWSER: Thousands of miles away at NOAA’s Pacific Marine Research Lab in Seattle, tsunami researcher Vasily Titov was also frustrated. It took him until 4 a.m. in the morning of the next day to run this computer model, because he didn’t have tsunami readings either.
VASILY TITOV, Researcher, NOAA: It already swept across the Indian Ocean and it was propagating toward the Atlantic at that time. So, yeah, if you think about it, by that time, thousands and thousands of people are already dying.
BETTY ANN BOWSER: Now, nearly two weeks later, with more data, Titov has expanded the model, and is the first scientist to show that the tsunami was a worldwide event and went way beyond the Indian Ocean basin.
VASILY TITOV: We are just starting to have the data. The data just started to come in from all over the world that’s showing that the tsunami actually propagated all across the ocean.
And in the Pacific, in the Atlantic Ocean there are tide gauges or sensors that picked up tsunami waves — small, but they were — they detected it.
BETTY ANN BOWSER: With such international implications for future tsunamis, and with the death toll now well over 150,000, the scientific community is coming together to call for a global tsunami warning system. It would be modeled after the only one that exists, NOAA’s Pacific tsunami warning system.
Over the past 55 years, it has detected killer tsunamis all the way from the northwest coast of the United States to Japan, and south to the west coast of South America. The Pacific Center was established after a tsunami hit the Hawaiian Islands in 1946, killing 159 people. Seismologist Dr. Charles McCreery is its director.
DR. CHARLES McCREERY: We have a destructive tsunami in the Pacific almost every year or every couple of years. And that’s why, really, the system had been developed for the Pacific.
In these other oceans it can be hundreds of years between these big destructive tele-tsunamis. And what we found out on Dec. 26, unfortunately, was that by not being prepared even for such a rare event, there was a high price to pay.
BETTY ANN BOWSER: All earthquakes do not trigger tsunamis; even big earthquakes on the ocean floor do not always cause tsunamis. But any time the center knows there’s been a major earthquake, they take it seriously. First, they look at seismic readings that come in from multiple stations.
BARRY HIRSHORN, Geophysicist, Pacific Tsunami Warning Center: We get signals from about 120 seismometers around the Pacific Basin. They’re measuring ground motion all the time in real-time and sending us the signals of the ground motion as it’s occurring, only 20, 30 seconds behind real-time.
We come in here, as quickly as possible we sit down at a terminal behind me here, and we… as soon as we have enough stations reporting, seismic stations, we locate the earthquake.
BETTY ANN BOWSER: Once they determine the size of the earthquake, they will then look at whether it will cause a tsunami. They first look at readings for more than 100 shore-based tide stations located around the Pacific Basin, near the shorelines.
The best equipment to detect if there is a tsunami are a series of deep-ocean monitors called “tsunameters,” developed by NOAA, that give readings from several locations around the Pacific Ocean Basin. Each tsunameter consists of an underwater platform and a buoy on the ocean’s surface. The platform contains equipment that measures changes in water pressure.
SPOKESPERSON: Let me show you this computer here.
BETTY ANN BOWSER: NOAA engineer Chris Meinig is one of the inventors of the system.
CHRIS MEINIG, Engineer, NOAA: This is the only system that can measure either the presence or absence, perhaps no wave. There’s many instances where you get an earthquake and no wave is generated, and that’s just as important to notice, to say, “hey, the population isn’t at risk, don’t sound the alarms, don’t clear the beaches of Waikiki, everything is okay.” But this is a physical measurement of the actual wave.
BETTY ANN BOWSER: This computer triggers an acoustic signal that is sent to the buoy, which sends that data to a satellite, which beams it back down to the tsunami center in Honolulu. If they determine a tsunami is likely, they issue a warning.
If big waves are headed toward the Hawaiian Islands, civil defense officials enter the picture. These sirens go off, alerting people to go to their TV sets and radios, where instructions for evacuation will be given. Along the beaches, tourists are moved into hotel buildings. Dr. Laura Kong is director of the International Tsunami Warning Center.
DR. LAURA KONG, Director, International Tsunami Information Center: Especially in Waikiki Beach we do have what’s called vertical evacuation, so that for any structure that’s more than six stories in height, any steel-reinforced structure, our official evacuation procedures, if there is no time, would be to go move people above the third floor.
BETTY ANN BOWSER: Even the phone books in Hawaii contain evacuation maps for every neighborhood along the coastline. The system worked well in 1952, and again in 1957, when tsunamis hit Hawaii.
DR. CHARLES McCREERY: In 1952, we had another big destructive tsunami. And because of the warning system there were no casualties.
We had no casualties again in 1957, a magnitude 9.1 earthquake. In 1960, the largest earthquake in recorded history, a magnitude 9.5 off the coast of Chile, produced a very big tsunami. We had a warning in Hawaii, but we did end up with 61 casualties here.
BETTY ANN BOWSER: The ultimate test of the Pacific warning system will come when a powerful earthquake takes place off the northwest coast of the United States.
FRANK GONZALEZ, Oceanographer, NOAA: How long did it take to reach the U.S. Coast, do you remember?
BETTY ANN BOWSER: Scientists like NOAA’s Frank Gonzales say it’s not a question of whether the earthquake will take place, but when. And the similarities between the earthquake zone off the northwest coast and Sumatra are frightening.
FRANK GONZALEZ: Each possesses what’s called a seismic subduction zone, in which an oceanic plate is forcing its way underneath a continental or land plate, and that forcing does not occur smoothly. The plate sticks – both of them stick because you’ve got rock on rock – and the pressure builds up for decades or centuries — and eventually it breaks, as it did off of Sumatra.
This coast will receive both a devastating shaking during the earthquake, which will destroy a lot of buildings, and so forth, and that will be followed by a very large, destructive tsunami.
BETTY ANN BOWSER: NOAA scientists are developing new technology that will not only improve the Pacific warning system, but could make a global tsunami warning system more affordable. Current cost estimates are in the billions. NOAA’s tsunameters cost $250,000 a piece to put into the ocean.
But when this new prototype is ready for mass production, it will be smaller and will cost one-half that amount. And scientist Vasily Titov says when there are more tsunameters in the oceans of the world, his computer model will be able to forecast tsunamis the same way the Weather Service does hurricanes.
VASILY TITOV: The way the tsunami warning system works now, it’s a, if you will, a reactive system. They see what happens and they react to that. They see a tsunami — I mean, earthquake happens, it may generate tsunamis, they react to that; they issue a tsunami watch.
It may be small, it may be large. That they don’t know for sure right now, and that’s what we’re trying to change.
BETTY ANN BOWSER: But even with more technology, scientists say no warning system will work unless communities have a comprehensive evacuation plan and educate their residents.
DR. LAURA KONG: It’s not only the technology for it, but it’s when a warning gets out, you want to make sure that governments and local agencies and emergency responders are able to act on that information instantly.
And so they have to be the ones to translate that message of a warning into an evacuation, and then get those people out of harm’s way.
DR. CHARLES McCREERY: When the sea withdrew, they went into those dangerous areas out onto the sea floor to… just out of curiosity. If they just had had that little bit of knowledge about the tsunamis to know that’s a natural warning sign and don’t go out there.
These are basic things that we teach in public education about tsunamis.
BETTY ANN BOWSER: Scientists from all over the world will meet next week in Japan to start laying the groundwork for a global tsunami warning system.