Experts puzzled by no tidal wave

Experts puzzled by no tidal wave

Jaymes Song, Associated Press/Ewa Beach, Hawaii

Tsunami experts could not understand why Monday's forceful
earthquake off Indonesia failed to produce massive waves similar
to those generated by the Dec. 26 quake that killed at least
174,000 people in the same region.

A magnitude 8.7 quake shook Indonesia's west coast, killing
hundreds of people and spreading panic that another devastating
tsunami was on the way.

There was no tsunami, but a small wave was detected by a tide
gauge on Cocos Island near Australia, about 2,400 kilometers
south of the epicenter, according to the Pacific Tsunami Warning
Center on Oahu (http://www.prh.noaa.gov/ptwc/).

"I'm baffled an earthquake this size didn't trigger a tsunami
near the epicenter," said Robert Cessaro, a geophysicist at the
center, which is operated by the National Oceanic and Atmospheric
Administration. It is responsible for monitoring seismic and
ocean conditions in the Pacific and alerting Pacific Rim nations
and U.S. agencies.

Center Director Charles McCreery said earthquakes of at least
8.0 magnitude usually generate major tsunamis.

"We expected some destructive tsunami with some distant
destructive effects. It was surprising," he said.

The latest event also demonstrated "there's a whole world of
uncertainty about trying to judge a tsunami based on the
earthquake data," he said.

The warning center initially estimated the Dec. 26 earthquake
to have a magnitude of 8.0, but it turned out to be larger, with
a magnitude of 9.0.

Monday's preliminary estimate was magnitude 8.5 but had no
destructive tsunami.

"The one we initially thought was bigger turns out to have no
effect," McCreery said. "The one we initially thought was smaller
had a huge effect. This is the challenge of tsunami warning."

The warning center, established in 1949, came under heavy
criticism following the December tsunami for not being more
aggressive about warning Asian nations and possibly saving
thousands of lives.

Earlier this month, a group of 58 European tsunami survivors
and relatives of victims sued NOAA and other agencies, alleging
the center did not do enough to warn people about the disaster.

"Although we certainly wish that somehow the event unfolded in
a way that we could've done more for the region, we really did
all we could under the circumstances," McCreery said.

Since then, several Indian Ocean nations have established
communications with the center and are now on its alert list. On
Monday, the facility was able to alert those nations.

The Indian Ocean has no warning center similar to the one in
Hawaii.