Tonga Hit By Strong Earthquake, Volcanic Eruptions

The U.S. Geological Survey says the 7.7 magnitude quake struck at 6:17 am local time on Friday, about 135 miles southeast of the Tongan capital, Nuku'alofa.

The U.S. Pacific Tsunami Warning Centre says sea-level readings indicate a tsunami was generated that may have been destructive along coasts near the earthquake epicenter, located 21 miles beneath the sea floor.

Tongans living along the coast moved inland after the alert but have now returned to their homes. No one was injured in earthquake and local officials say there was little damage.

Undersea volcano shoots a column of gas and ash into the air above the Tongan islands. March 18, 2009. (Photo credit unknown)

Tonga is an archipelago of 170 islands about halfway between Australia and Tahiti. It is part of the Pacific ring of fire, an arc of earthquake and volcanic zones.

This earthquake region is dominated by the convergence of the Pacific and Australia plates in the Earth's crust, the USGS explains. The Pacific plate is slidiing slowly westward beneath the Australia plate at the Tonga trench, producing one of the most active earthquake regions in the world. There are 36 undersea volcanoes clustered in the area.

Tongan government geologists intend to investigate the extent of the underwater eruption and the impact it will have on the environment as soon as a dispute over which government agency will pay the diesel fuel bill for a Tongan Navy patrol boat, Radio Australia reports.

Undersea volcanic eruptions have been sending clouds of smoke, steam and ash into the air over the Tongan islands since Monday that are visible in the capital city, which has been shaken by a series of smaller earthquakes.

On Wednesday, a volcano produced a spectacular eruption about six miles from the southwest coast of the main island of Tongatapu, shooting columns of volcanic material thousands of feet into the sky.

Residents have not been endangered by the atmospheric pollution due to the prevailing trade winds that are blowing the volcanic gas and steam away from the island.

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