MENTAWAI ISLANDS, Indonesia — Costly warning systems installed across Asia since the deadly 2004 tsunami did nothing to save villagers on these remote Indonesian islands who saw homes and loved ones swept away by a giant wave this week.
Such systems can be effective for people living hours away from where a tsunami is forged but are often unable to help those most at risk. Officials say a 10-foot wave struck the Mentawai Islands on Monday just minutes after a massive earthquake offshore, killing more than 400 and destroying hundreds of homes.
There are questions about whether Indonesia’s system was working properly. Even if it was, a tsunami generated by an earthquake so close to shore can reach land long before there is a chance to raise an effective alert, experts say.
The Mentawai Islands do not have sirens to warn of tsunamis, said Prih Harjadi of Indonesia’s Meteorology, Climatology and Geophysics Agency. The area is also not covered by a system of buoys that measure shifts in sea level.
Indonesia has land-based seismometers that picked up Monday’s quake and sent a computer-generated tsunami warning to local earthquake-monitoring agencies in just under five minutes. But even if there had been more time, the alert went only to agencies, not to the general population.
Renato Solidum, director of the state-run Philippine Institute of Volcanology and Seismology, said seaside communities needed to learn to read natural signs — such as earthquakes and unnaturally receding seas — and immediately move away from the coast even before alarms go off.
Scientists insist the warning systems are necessary. The 2004 tsunami, also triggered by a quake off Indonesia, proved that distance from a quake’s epicenter offers little protection.
Half of the nearly 230,000 dead were on the Indonesian island of Sumatra, but powerful waves also moved at jetliner speeds across the Indian Ocean, slamming into coasts of countries thousands of miles away.
