Weathernews Inc. has started a new service that provides tsunami information online using radars that can detect the waves within 30 km of the coast and capture images of them as fast as 15 minutes before they reach shore.

The radars are located at nine sites along the coastlines of Aomori, Iwate, Miyagi, Fukushima and Ibaraki prefectures, which were devastated by last March's monster waves, Weathernews spokesman Hitoki Ito said Tuesday.

The radars are able to detect tsumani that are at least 3 meters high and update their progress across the Pacific Ocean every two seconds, right up until the moment they smash into coastal areas, Ito said. "The defining difference between our service and the Meteorological Agency's is that ours does not provide a forecast, but live tsunami coverage," Ito said. "We think our system supplements the agency's."

However, Weathernews is only legally permitted to issue live images of tsunami with information on their location via its service, which began March 1. Under the law, only the Meteorological Agency can broadcast the estimated time tsunami will hit the coast and their forecast size.

Weathernews' system monitors information from radars 24 hours a day, and when a tsunami is spotted it sends out an alert by email or other online communication direct to municipalities and corporate users. The service is only available to contracted municipalities and companies, and there are no plans to offer it to the general public, Ito said.

The radars are similar to those used by fishing boats to detect and track the movements of other vessels to avoid collisions. Ito said Weathernews specially modified them to detect changes on the surface of the ocean, adding the company hopes to expand the system nationwide.