The India-Australia and Eurasia plates that hold the Earth's surface are lodged on top of each other deep under the ocean near the Indonesian island.

"As the India-Australia plate was digging under deeper and deeper and causing too much strain, the plates slipped -- on a large scale," said Yoshinobu Tsuji, assistant professor at the Earthquake Research Institute of the state-run Tokyo University.

The result on Sunday was an earthquake of 9.0 on the Richter scale -- one of the most powerful in history.

The deep-sea destruction throws a huge amount of water to the surface. The waves at first can appear minor, but build up a deadly velocity as they race hundreds of kilometers (miles) across the ocean.

When the tsunami waves finally reach land, the shallow water causes their speed to slow -- but their size to grow gigantic.

More than 16,000 people have been confirmed dead as the tsunamis swept away everything in their path in eight countries, many full of beach resorts packed with holiday-season tourists.

Yoshimitsu Okada of the state-run National Research Institute for Earth Science and Disaster Prevention said the raw power of Sunday's quake must have been 500 times as great as the Kobe quake 10 years ago that measured 7.3 on the Richter scale and killed more than 6,000 in Japan.

The Kobe earthquake's 10-year anniversary will be marked next month with an international conference on disaster management.

Japan has improved its disaster response time since the Kobe quake. It has long had in place a rapid alert system for tsunami waves whenever a temblor strikes.

But the infrastructure in place for the Pacific does not exist for the Indian Ocean, a less prosperous region which experiences fewer tsunamis.

Tsuji noted that the waves that India and Sri Lanka had taken two hours to reach their shorts, but no warnings were issued.

"People were hit by tsunamis all of sudden without having warnings," Tsuji told a private television network.

Another expert from Tokyo University, Keiji Doi, said the awareness of people in the Indian Ocean about tsunamis "was not high."

"Indonesia has experienced tsunamis many times," Doi said. "If the nation had known about the danger of tsunamis, however, it did not have any system to convey the fears to other countries along the Indian Ocean."

Japan's national Tohoku University has transferred the country's advanced tsunami prediction technology to 15 other countries but they are all in the Pacific region, the Yomiuri Shimbun said.

"Without any tsunami warning center, people in places who did not feel the tremor were probably unable to know tsunamis were coming over," the daily quoted Tohoku University professor Fumihiko Imamura as saying.

But even with its technology, Japan could also learn from the disaster, newspapers said.

"Wariness for tsunamis cannot be said to be high enough even in Japan," the Tokyo Shimbun said, noting that some people had ignored the threat of waves to check on ships and other facilities at sea after recent major quakes.

"We must renew our preparations by recognizing the disaster this time was not what happened only in the distant Indian Ocean but something that can happen in Japan," the newspaper said.

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