The United States plans to expand its tsunami warning system capabilities
by deploying new technology to detect and monitor such waves in
the Pacific, Caribbean and Atlantic basins.
The
government has pledged $37.5 million over the next two years for
the project, which includes the production and deployment of 31
new DART buoys, (Deep-Ocean Assessment and Reporting of Tsunamis)
manufactured by Science Applications International Corporation.
There are currently six DART buoys in operation in the Pacific
Ocean, with three in the Gulf of Alaska, two off the coast of Oregon
and one in the deep waters of Oahu, Hawaii. The National Oceanic
and Atmospheric Agency jointly operates another buoy in the southern
Pacific with Chile.
“The DART technology is the only technology in the world
that we know works,” said Laura Kong, director of the International
Tsunami Information Center, based in Honolulu, Hawaii.
According to Kong, two other countries—Germany and India—have
developed DART-like technologies. But these technologies have not
been scientifically documented. In August, Germany unveiled an instrument
that it plans to deploy for the first time off the western coast
of Sumatra, Indonesia. India has yet to deploy its technology.
The U.S. DART system measures waves in the open ocean. It links
two components: a sensitive pressure sensor, called a tsunameter,
that sits at the bottom of the ocean, and a buoy that transmits
pressure data to the country’s two warning centers.
“It’s the only direct measurement of a tsunami wave,”
said Christian Meinig, director of engineering at NOAA’s Pacific
Marine Environmental Laboratory. He helped to develop, design and
build the original DART technology at PMEL.
This month, SAIC begins work on the new system, known as DART 2,
according to Chuck Fralick, operations manager at the company.
DART 2 has a two-way communications link, said Meinig. The original
DART system could only transmit data, he said. With the new system,
someone at the warning center can initiate communication with the
buoy. For instance, if there was a seismic event, you could tell
the buoy to go into a high state of recording, he said.
DART 2 also incorporates new technology to double the life span
of the electronic systems. Before, the buoy systems lasted one year,
its deep ocean sensors for two. Now the systems can last two years
and four years, respectively, said Fralick.
The current DART buoys transmit information via NOAA’s high-power,
40-watt Geostationary Operational Environmental Satellite (GOES).
The new system will transmit using an Iridium commercial satellite.
Far below the surface of the ocean, the tsunameters can detect
small changes in pressure, such as a wave smaller than 1 centimeter
high, passing over.
“They have a resolution of a quarter millimeter,” said
Meinig.
Tsunameters sit upon the seafloor, 2,000 to 6,000 meters beneath
the ocean’s surface, held in place by a 720-pound anchor.
The package includes a bottom pressure recorder, a computer and
a transducer. Nearby, a moored 2.5-meter disk buoy carries an acoustic
modem to communicate with the tsunameter. The buoy sends information
via satellite to the National Data Buoy Center, the Richard H. Hagemeyer
Pacific Tsunami Warning Center in Ewa Beach, Hawaii, and the West
Coast/Alaska Tsunami Warning Center in Palmer, Alaska.
“I truly believe these things can measure any significant
tsunami wave in the ocean,” said Fralick.
The original six DART buoys were placed in late 1990s, said Meinig.
But they didn’t become fully operational until late 2003.
Shortly after, one of the buoys detected a tsunami of only a few
inches created by an earthquake near the Aleutian Islands in Alaska.
That information helped the Pacific Tsunami Warning Center to decide
there was no reason to issue a warning for Hawaii.
“That saved millions of dollars,” said Delores Clark,
spokesperson for NOAA, because it prevented the need for evacuating
millions of Hawaiians unnecessarily.
The DART technology came about because of a galvanizing event,
said Meinig. In 1992, a 7.2 earthquake in California generated a
tsunami that killed no one. But it raised concerns that a bigger
earthquake could produce life-threatening tsunamis along the west
coast. Congress asked NOAA to assess tsunami awareness and preparedness
of the west coast. The agency approached scientists at the Pacific
Marine Environmental Laboratory to design a system to detect tsunamis
in the Pacific. The scientists created DART, then transitioned it
to SAIC, which now owns the technology, said Fralick.
Five tsunami warning systems exist around the globe. They are located
in the United States, Japan, Russia, French Polynesia and Chile.
The Pacific Tsunami Warning Center was created in 1949 following
a 1946 tsunami that devastated a town in Hawaii, said Clark. The
center in Alaska was set up in 1965 following an earthquake that
measured more than 9 on the Richter scale, she said.
These warning centers monitor the pressure sensor data recorded
by the DART buoys and transmit tsunami bulletins when appropriate.
States affected by the bulletins then alert local authorities who
then evacuate coastal areas.
“It’s up to the county and local communities to determine
how they’re going to notify the public. Some have sirens;
some have other methods,” said Wilson. He said a senate bill
in the Oregon state legislature has proposed a uniform siren signal
to be coordinated among the local authorities along the state’s
coastline.