Underwater quake, volcano off Tonga

NUKU'ALOFA, Tonga, March 19 (UPI) -- A major underwater earthquake struck in the Pacific Friday, 132 miles off the island nation of Tonga.

An underwater eruption was in progress closer to Tonga, The Times of London reported. Scientists had not determined if the two were related.

The U.S. Geological Survey reported the tremor had a magnitude of 7.9 on the Richter scale, just short of a rare great quake. The Pacific Tsunami Warning Center issued a warning for Tonga, Fiji, American Samoa and some other mid-Pacific islands and said Hawaii could experience minor changes in sea level and alterations in ocean currents, CNN reported.

"There's a tsunami in the water, but it's not gonna do much," said Robert Cessaro, a scientist with the center.

The underwater eruption has been sending up plumes of smoke and ash for several days, the Times said Thursday. Before Friday's quake, there had been other smaller tremors.

The volcano appears to be 6 miles to 7 miles off the main island, Tongatapu, with the eruption visible from the capital, Nuku'alofa. Australian scientists were en route to Tonga.

The eruption had not posed any risk to Tonga residents, local officials said, although that could change.

"Underwater volcanoes can be violent, and have a strong climatic effect," said Simon Turne of Macquarie University in Sydney.