Tsunami prediction technology proves its worth

Underwater sensors fed accurate projections of recent tsunami; above ground, social media got the word out

What a difference six years can make for applied technologies. Just ask Vasily Titov, senior tsunami modeler at the National Oceanic and Atmospheric Administration’s (NOAA) Pacific Marine Environmental Laboratory in Seattle.

When a magnitude 9.1 temblor struck Sumatra, Indonesia, in 2004 and created a 100-foot tsunami that killed more than 200,000 people, researchers were largely in the dark and there was little warning that the wall of water was racing for the vulnerable shores. When the magnitude 8.8 quake struck Chile on this Feb. 27, on the other hand, Titov’s team was providing detailed and accurate reports in hours about what potentially affected communities should expect.

The difference? A worldwide network of tsunami-detection devices.

In 2008, NOAA deployed the final two of the 39 deep-ocean Assessment and Reporting of Tsunami (DART) detection buoys that make up the U.S. tsunami detection system. When the 2004 earthquake struck Sumatra, only six of the buoys were in place and only half of those were actually working, Titov said, and none of the working ones were in the Indian Ocean.

Related: 2004 tsunami spurred development of NOAA warning system

Today, the entire tsunami-detection network – including devices provided by other countries – includes 50 buoys around the world and is in mostly good working order.

During the Indian Ocean tsunami, Titov said, “it was mostly frustration.” His group had to manually plug in data primarily derived from tide gauges, which are  “confusing and so difficult to interpret,” he said. The team was unable to deliver a report until eight hours after the disaster had already happened.

Tide gauges can be affected by underwater geography near the shore and don’t give an accurate picture of the strength and direction of tsunamis.

DART buoys, on the other hand, are placed in deep water. A sensor is dropped from the buoy to the ocean floor and by measuring water pressure it can detect movement of a tsunami wave only a centimeter in height.

As it happened, when the earthquake struck Chile, the closest buoy – one managed by Chile – was out of commission. So Titov’s team had to wait for the wave to reach the first buoy in the U.S. array, which took approximately three hours. Once it did, the team was able to make forecasts almost instantly. “The forecast played out pretty well – very well, in fact – for all locations, including Hawaii,” he said.

There is still significant work to do on the system, Titov said. When a tsunami approaches the shore, its characteristics – and the amount of damage it can do – depend to a large extent on the underwater geography. Accordingly, forecasters need to profile shorelines to make accurate predictions. So far, NOAA has created 43 out of a planned 75 local profiles. And once researchers have finished with creating the profiles, they’ll need to begin updating them. That’s because underwater geography changes over time, due to such factors as construction at ports and changes in rivers that empty into the ocean.

Titov would also like to see a second set of buoys deployed further out to sea. “Right now we have just this one line of defense,” Titov said. “It would be a good idea to have a second line, not as extensive as the first.” If a second line of buoys is placed further from shore, it would not only provide redundancy, but give researchers an easier time of sorting out the measurements of earthquake waves transmitted through the ground from measurements of tsunami waves transmitted through water.

New technologies also played a significant role in getting the word out to potentially affected communities.

The U.S. Pacific Fleet relied primarily on social networking technologies – most notably, Twitter and Facebook – to keep local media and Navy families informed about the potential effect of the approaching tsunami.

“We immediately first went out with a post on Twitter and Facebook,” said Capt. Jeff Breslau, public affairs officer with the U.S. Pacific Fleet in Honolulu. “What we found is that there was no need to do a press release.” Local media cited the Navy’s Twitter reports, and the Pacific Fleet’s Facebook page experienced a surge in activity, as local residents checked the site for updated tsunami news.

“Over the past 18 months I’ve viewed social media as the centerpiece on how we can communicate with the public and the media,” Breslau said. “But for all that I never envisioned that I just would not do a press release.”

About the Author

Patrick Marshall is a freelance technology writer for GCN.


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