Researchers find way to predict areas likely to be swamped by tsunami

A team of researchers has developed a way to map areas likely be swamped by towering tsunami based on data obtained during 10 minutes after a huge earthquake strikes.

Currently, it takes more than 30 minutes to chart areas that will be affected.

But with a high-performance computer, the time can be shortened, which could save countless lives as people evacuate swiftly before a tsunami reaches their homes and offices.

The method was established by Yuichiro Tanioka, a professor of seismology and tsunami at Hokkaido University, and other researchers.

"It will be easier for people to grasp the scope of tsunami if we provide a prediction of not just how high tsunami can reach but also areas on the map that will be inundated," Tanioka said. "Our idea is to devise a method that will be helpful to evacuation."

Experts say assessments of a massive earthquake tend to underrate scale because of a reliance on immediate data. A case in point is the Great East Japan Earthquake last year, which the Japan Meteorological Agency initially registered as having a magnitude of 7.9. This was later revised to magnitude 9.0, making it the most powerful earthquake on record to hit Japan.

Using records of that event, Tanioka's team estimated the seismic center and the scope using "W phase" algorithm, a way of gauging magnitude more quickly and accurately from seismic waves.

It then computed a tsunami’s run-up height by figuring out the approximate length and width of a fault and amount of slip to show areas that would likely be affected.

When the team reviewed the initial prediction of tsunami hitting Minami-Sanriku, Miyagi Prefecture, it found the height of tsunami forecast based on data observed over five minutes after the quake struck had been underestimated.

But the prediction made on data obtained during 10 minutes after the quake correlated with the height of tsunami and areas affected.