Japan Earthquake Sends Pacific Tsunami Warning Data Network into Action

By Wayne Rash  |  Posted 2011-03-11

Japan Earthquake Sends Pacific Tsunami Warning Data Network into Action

Out in the open ocean across the Pacific there are devices called DART, or Deep Ocean Assessment and Reporting of Tsunamis, buoys. If you saw one, it wouldn't look like much, just a round device painted orange and white with a short mast bearing a wind gauge and a couple of satellite antennas.  

On the side is painted the word "Tsunami." Yet, despite their unassuming looks, these buoys are the critical reporting terminals for a worldwide data network linked to computers in Hawaii and elsewhere. This is the visible evidence of the Pacific Tsunami Warning Center. 

When the massive earthquake struck Japan on March 11, it triggered shock waves that became a Pacific-wide tsunami. The DART buoys dutifully reported the passing of the wave, and that allowed the National Weather Service staff at the Pacific Tsunami Warning Center to accurately predict the arrival time of the waves that would strike Hawaii and the U.S. West Coast in a matter of hours. 

The DART buoys are the visible half of a two-part system. Resting on the ocean floor below them are pressure sensors that transmit acoustic data to the buoy on the surface, which then combines it with its own observations of weather and wave action before instantly transmitting that data to a GOES (Geostationary Operational Environmental Satellite) satellite. Then the satellite forwards the information to the tsunami-warning center.  

Each of these buoys, located mostly around the highly seismically active Pacific Rim (also known as the "Ring of Fire"), reports the signs of a tsunami as it passes. Once this data is gathered and processed at the tsunami-warning centers in Hawaii and elsewhere, it delivers a nearly instantaneous, real-time picture of the speed, direction and severity of a tsunami. 

As the waves arrive, they trigger a device called a tide station. These perform a similar function to the DART buoys, but they are attached to piers and other coastal structures, and measure the actual severity of the tsunamis as they arrive from the open ocean. Again, these devices send their observations to the Pacific Tsunami Warning Center. When a 36-foot-high wave came ashore at speeds estimated at 600 miles per hour in Japan, this information was reported, and used by the center to estimate the seriousness of the threat as it struck other land in the Pacific. 

Although the Pacific Tsunami Warning Center occupies an unassuming building in Ewa Beach, it is run by NOAA (the National Oceanic and Atmospheric Administration) and its impact is global. The PTWC is also the headquarters for the new tsunami-monitoring efforts in the Indian Ocean and in the Caribbean, which were put into place after the deadly 2004 tsunami triggered by an earthquake in the Indian Ocean off the west coast of Sumatra, Indonesia, that killed about 230,000 people in the region. 

Warnings are Futile if People Don't Respond


At the time, the PTWC was the only agency to detect that tragic event, but its warnings to governments surrounding the Indian Ocean went mostly ignored, with deadly results. Now, a warning system is in place, and for the moment, it's all run by the U.S. National Weather Service on behalf of the United Nations. 

The only other visible sign of this global data network is something you see only if you know what to look for. Back in the late 1990s, when I first started working with the University of Hawaii's Advanced Network Computing Lab to test enterprise-class products for the long-departed CommunicationsWeek, where I was the reviews editor, I happened to be driving along the north shore of O'ahu when I spotted some tall masts topped with sirens. I asked my friend and colleague Brian Chee who created the lab what those might be. "They're the tsunami-warning sirens," he told me.  

On March 11, those sirens began sounding hourly, warning residents of low-lying areas throughout Hawaii to seek higher ground. The sirens were triggered as the last stage of the tsunami-warning data network. You might consider that these are the human interface of this vast global network that starts with reports of earthquakes and continues with measurements of ocean waves by a string of sensors spanning thousands of miles of open ocean. 

Unfortunately, those sirens aren't everywhere in vulnerable areas. However the data network operated by the Pacific Tsunami Warning Center is nearly everywhere, and it has the ability to provide timely warnings, which, if heeded, can save the lives of hundreds of thousands of people. But, sadly, if they're ignored as they were in 2004, those same numbers can be lost. In the United States where warnings are usually taken seriously, the March 11, 2011, earthquake in Japan and the subsequent tsunami were taken seriously, and people were evacuated. 

But a global data network can do only so much. As critical as this infrastructure is, it only works when it's used. The good news is that most governments in the Pacific and in the Indian Ocean now take the threat seriously, they have plans in place to evacuate residents in affected areas, and they probably won't be struck by the unimaginable loss of life that happened in 2004. 

But there's another tsunami warning area that gets little attention. It monitors the North Atlantic, the Mediterranean and the seas connected to them. The Atlantic Ocean is also capable of generating tsunamis as the Atlantic Ocean spreads along the mid-Atlantic ridge. Imagine a 36-foot-high tsunami coming ashore in Manhattan, and then ask yourself where the warning system is and where you'd go to evacuate.


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