EDITORIAL: Tsunami warnings

More than 40 hours after a catastrophic earthquake struck Chile, the Japan Meteorological Agency on Monday finally lifted all of its tsunami warnings.

The agency initially issued a major tsunami warning, predicting waves of up to 3 meters along the nation's northeast coast. But the highest wave actually recorded was 1.2 meters, and an agency official later apologized for "overestimating the danger" and "causing inconveniences by not lifting the warnings sooner."

The tsunami waves that traveled across the Pacific Ocean were triggered by an earthquake in a distant country where little information of the actual damage was initially available. Faced with the difficulty this situation posed for making any accurate tsunami prediction, the agency wavered on whether to issue its first major tsunami warning in 17 years.

The agency ultimately decided to go with a "worst case scenario."

The agency has issued warnings of waves exceeding 1 meter on eight occasions since the current tsunami warning system was introduced in 1999. However, with the sole exception of the tsunami caused by the Tokachi-oki earthquake of September 2003, those waves never reached the predicted levels. This became a subject of Diet debate.

The agency needs to improve the accuracy of its predictions by refining its technology for assessing the scale of earthquakes and the depth of their focuses. That said, however, we believe the agency was right to "err on the side of caution." The decision was quite understandable.

Our only concern is that this may have the effect of predisposing people to underestimate future tsunami warnings. In this sense, it is vital that the government and local administrative authorities find out how people processed and acted on the warnings this time.

On Sunday, nearly 1.5 million people were instructed or recommended to evacuate their homes. But even in the three Tohoku region prefectures where a major tsunami warning was issued, well under 10 percent of residents actually went to designated evacuation centers.

Some people may have voluntarily headed for higher ground or sought refuge on the upper floors of tall buildings. And since it was daytime on Sunday and the tsunami waves were not expected to hit for hours, many people likely decided to stay home with their families and follow the warning updates.

According to news reports, many residents who felt safe after the arrival of the first wave left the evacuation centers and went home. Vessels returned to ports after riding out the first tsunami wave offshore. Were these people not told that the second and third waves could be more destructive than the first?

And how did elderly and disabled people fare? Were their neighbors watching out for them to make sure they would be the first to reach safety? Or did local administrative entities do nothing beyond just issuing evacuation instructions and recommendations? All these questions need to be answered.

Experts predict that tsunami generated by the expected Tokai, Tonankai and Nankai earthquakes, whose epicenters will be in waters off the Japanese archipelago, will kill between 1,000 and several thousand people.

With each of these temblors, the proximity of the epicenter means the tsunami will hit sooner--within a few minutes to several tens of minutes. And the quakes could strike at night when people are asleep.

The fundamental rule of survival is to move away from the coast or the mouth of a river as soon as an earthquake shock has been felt, even before a tsunami warning is issued.

It was fortunate that no lives were lost in Japan this time, but we must not become complacent. There are many things to learn from this "major tsunami that did not come."

--The Asahi Shimbun, March 2