TOKYO Japan's weather agency apologised on Monday for "crying wolf" when it urged some 1.5 million people to evacuate ahead of a possible major tsunami, only to find the waves that finally hit were far smaller than feared.
Experts defended the agency's decision to warn that waves of 3 metres (9 ft 10 in) or more might strike Japan's Pacific coast after a huge earthquake hit Chile, but acknowledged the risk of making residents blase about the danger next time.
"In the end, (the warning) was a bit excessive. I would like to apologise for the fact that the warning lasted so long," Jiji news agency quoted Japan Meteorological Agency official Yasuo Sekita as telling a news conference after all warnings and advisories had been lifted, some 25 hours after the first alert.
Tsunami warnings are common in Japan, one of the world's most earthquake-prone countries, but Sunday's alert was the first for a major tsunami in 17 years and only the fourth since 1952.
The alert came after the Pacific Tsunami Warning Center (PTWC) had issued a Pacific-wide warning that included Hawaii and stretched across the ocean from South America to the Pacific Rim.
"I don't question the wisdom of their warning. The key thing to remember is that they cannot underwarn. That is not an option," Dailin Wang, an oceanographer at the PTWC, told Reuters.
Predicting the height of a tsunami is a complex task that requires not only knowing the quake's magnitude but harder-to-grasp information about the impact on the sea floor and detailed data about the coastal areas that could be hit, Wang said.
Still, warnings of impending disaster that don't pan out could encourage people to ignore future alerts, he said.
"If we do that all the time, we cry wolf and lose credibility," Wang said. "We have to improve."
Japanese are already fairly immured to tsunami warnings, despite past tragedies, including one that killed 140 people 50 years ago after a massive quake struck Chile.
On Sunday, only about 6 percent of residents in areas warned of waves of 3 metres or more evacuated, a Yomiuri newspaper survey showed.
"Citizens were not sufficiently aware of the danger of tsunami," said Chief Cabinet Secretary Hirofumi Hirano.
"We don't know when a tsunami will occur again, so together with local authorities we must review this problem," he said.
(Editing by Chris Gallagher)