Earthquake scientists always talk about "the big one," the ultimate temblor expected some day along the Wasatch Fault. But even Utah's worst seismic nightmare — a 7.5 magnitude earthquake — would be nothing compared to the underwater earthquake that devastated coastal regions in Asia on Sunday.

It would take about 180 simultaneous 7.5 magnitude earthquakes to equal Sunday's 9.0 level quake, says Walter Arabasz, director of the University of Utah's seismograph stations.

"We strain our imaginations to comprehend what this means in terms of energy released," says Arabasz, who offers this analogy: It would take 2 million 23-kiloton bombs like the one detonated by the United States in 1946 on Bikini Atoll to release the same energy as a magnitude 9.0 earthquake.

Earthquake faults along the rim of the Pacific Ocean basin and around parts of the Indian Ocean are much longer than those in the Wasatch range, Arabasz says, and therefore can accumulate and release much more energy. Utah will likely never experience a quake worse than magnitude 7.5, according to Arabasz.

Currently, seismic scientists "just don't have earthquake prediction in our tool kit," Arabasz says. "In hindsight we realize that some earthquakes were preceded by small foreshocks," but not all foreshocks result in earthquakes.

Because it can take at least a couple of hours for an underwater earthquake such as Sunday's in Indonesia to reach distant shores like those in Sri Lanka, it would have been possible to warn those residents — that is, if there had been a tsunami warning system in place for the Indian Ocean, Arabasz says. "This is standard practice in the Pacific Ocean basin following the 1964 great Alaskan earthquake."

Geologist Kerry Sieh of the California Institute of Technology said Sunday's quake was so strong, it probably jolted the planet's rotation. "It causes the planet to wobble a little bit, but it's not going to turn Earth upside down," Sieh said.

By Monday, according to the International Tsunami Warning Center in Hawaii, some energy from Sunday's waves sifted into the Pacific Basin.

At Manzanillo, Mexico, waves rose more than 8 feet. Minor fluctuations were reported in New Zealand and Chile, where waves rose between 1 and 2 feet. In the United States, Hawaii reported almost no wave changes, while San Diego saw waves rise less than a foot.

"It's been a multi-ocean tsunami," said Stuart Weinstein, a geophysicist with the Pacific TsunamiWarning Center on Oahu. "It's probably the first multi-ocean tsunami since Krakatoa."