Japan has expertise in tsunami alerts

When residents of the northern Japanese Island of Hokkaido were jolted awake by a pre-dawn magnitude 7.1 earthquake in November they only had to jump out of bed and flick on the TV to get an almost instant tsunami warning.

The 10 cm (4 inch) high wave that lapped the shores about half an hour later was a far cry from the towering walls of water that crashed onto Indian Ocean coastal areas on December 26, killing nearly 1,60,000 people and leaving millions homeless.

But the expertise that makes such alerts possible could help create a warning system in the Indian Ocean similar to one set up in the Pacific after a 1960 quake in Chile triggered a tsunami that hit the Japanese coast and killed more than 100 people.

"We have leading technology in creating a database which analyses earthquakes and estimates tsunami," said Akira Nagai, deputy director of Japan Meteorological Agency's earthquake and tsunami observation division.

"We're happy for them to have all the knowledge we have," Nagai said at a monitoring centre in Tokyo, where large wall monitors display seismic activity and computers instantly map the focus and intensity of quakes and predict whether a tsunami is likely to hit Japan's shores.

Japan's Tsunami warning system has been upgraded several times since its inception in 1952, including after a 7.8 magnitude quake in 1993 almost instantly triggered a 30-metre high wave before a warning could be given. About 190 of the 230 people killed in the quake were victims of the surging sea.

The tsunami warning service, which has six regional centres, now aims to issue alerts within three minutes after a quake.

Signals from 180 seismic stations across Japan and about 80 water-borne sensors are monitored 24 hours a day by a computerised Earthquake and Tsunami Observation System (ETOS).

To get warnings out quickly, the JMA and media have developed a system to superimpose alerts on TV screens as soon as they are issued. There is even a proposal for a system that would automatically turn on TVs in the event of an evacuation order.

In addition, warnings are sent to local officials via a satellite system that acts as a backup to land-based communications. Local officials activate sirens and loudspeaker systems as well as decide if an evacuation advisory is needed.

Costly System

Japan also has built countless concrete breakwaters and floodgates to protect ports and coastal areas around the country, although experts say they may not be enough to prevent tsunami-caused disasters, and could even worsen the damage by keeping the water from receding.

The warning system comes with a hefty price tag - about $20 million annually to keep it running.

That the word tsunami itself is Japanese - meaning, "harbour wave" - reflects the quake-prone country's long and sometimes tragic experience with the phenomenon.

In 1896, a magnitude 8.5 Sanriku earthquake and tsunami left more than 22,000 dead in northeastern Japan. Another 8.1 temblor hit the same region in 1933, killing 3,064.

About 17 per cent of all tsunamis between 1900 and 2001 were generated in or near Japan, more than any other area, according to the Pacific Tsunami Warning Centre in Hawaii.

Forecasting tsunami is only part of the battle, however.

Most of the impoverished areas hit by the Indian Ocean tsunami lack the communications infrastructure needed to get warnings to local officials and residents quickly.

Equally important is making people in an area where tsunamis are uncommon of the need to evacuate. Even in Japan, some people wander down to the shore after a warning to have a look and many ignore warnings because often no big tsunami strikes.

"The countries that were hit this time were hit hard simply because they didn't have much experience," the JMA's Nagai said.

"I'd like to stress that it is important to educate people what to do when a warning is issued."