ENVIRONMENT
08/21/2011 07:16 pm ET Updated Dec 06, 2017

Japan Tsunami First To Be Observed By Radar, Could Lead To New Early Warning Systems

There is new hope for early warning systems in the wake of Japan's March 11th tsunami.

For the first time, a tsunami has been detected by radar -- the devastating wave was observed by high-frequency radars in California and Japan as it raced towards their coasts, according to Professor John Largier, an oceanographer at the University of California, Davis and an author of the paper describing the work, published in the journal Remote Sensing.

"The tsunami was detected by the radars between 10 and 45 minutes prior to its arrival at neighboring tide gauges," Largier says in the paper.

For the last 10 years, high-frequency radars have been used to study ocean currents by Largier and his colleagues.

Regarding the west coast of the U.S., Largier told CNN, "We have the hardware set up. We have the system operational. It's a software challenge that we show we can achieve."

"Such a detection system could provide a 15-minute warning for a tsunami approaching northern California and an early warning of an hour for southern California, where the shallow continental shelf along the coast is bigger," he said.

Largier said using radars to detect tsunamis could be useful where there are wide areas of shallow seas, such as the east coast of the U.S. or Southeast Asia, ScienceDaily reported. He told CNN that an hour's warning could be provided with an early detection system off the U.S. East Coast and a warning of several hours for Southeast Asia.

The scientists found the radar picked up the changes in currents as the wave traveled, rather than the actual tsunami wave, which is a small height while out at sea.

They were able to see the tsunami once it entered shallower coastal waters over the continental shelf, when the wave slows down, increases in height and decreases in wavelength, ScienceDaily reported.

On August 8th, head of the Japan Meteorological Agency Akira Nagai, admitted that the mistaken three meter height forecast of the more than 10 meter high March tsunami "led to a slow evacuation," Nature reported.

At the press conference, Nagai presented a revised early-warning system, which warned of "the possibility of a huge tsunami" for an earthquake with a magnitude eight and above, rather than the wave's actual height.

According to Nature, the system used on March 11th measured seismic signals during the first minute of an earthquake. However, this tended to underestimate the quake, and therefore the tsunami, for earthquakes lasting more than a minute.

The agency will start discussions of an overhaul of the system in September, according to the press conference.

Earlier this month, scientists discovered a link between icebergs being created in Antarctica to the March tsunami.

---