Strong Earthquakes Hit Papua New Guinea, Tonga
Sydney Morning Herald
There were no immediate fears of tsunamis being generated by either of Sunday's quakes, which were both deep below the Earth's surface, the Pacific Tsunami Warning Center in Hawaii said.
Tonga, a nation of about 169 islands and 115,000 people, was hit by a quake measuring 6.7 in magnitude at 4.36pm local time, US and Australian seismologists said.
It came 10 minutes after a quake with a magnitude of 6.2 off the remote and sparsely populated New Britain island in the east of Papua New Guinea, one of the most seismically active regions in the world.
"I think this is pretty typical," Geoscience Australia seismologist Spiro Spiliopoulous said of the two quakes.
"Statistically it's probably a little unusual to get two quakes of this size occurring within half an hour of each other but I'm not getting any reports of damage," he told Reuters.
The Tonga quake was located about 145 kilometres north-east of the capital Nuku'alofa and was most likely related to a larger quake measuring 7.9 in magnitude which hit without causing major damage on May 3.
"It's part of the aftershock sequence of the big event a few weeks ago," Spiliopoulous said.
The May 3 quake generated a small tsunami of about half a metre but caused panic across the Pacific, with memories still fresh of the huge December 2004 tsunami that left 230,000 people dead or missing across large parts of Asia.
It caused evacuations in New Zealand and Fiji and was followed by a 6.0 aftershock the next day.
On May 16-17, Pacific Basin countries staged Exercise Pacific Wave 2006, a tsunami warning drill that revealed mixed results including an overloaded telephone network in Thailand and a faulty fax machine in Malaysia.
Spiliopoulous said the latest quake had been centred too far away from the Tongan capital to cause major damage.
One woman in Nuku'alofa, who asked not to be identified, said the quake had been felt but it had not been big enough to cause any major concern.
The Tonga islands are an archipelago east of Australia, south-east of Fiji and north-east of New Zealand.
The Pacific Tsunami Warning Center initially registered the PNG quake with a magnitude of 6.7. It was estimated at a depth of 39 kilometres, while the Tonga quake was put 50 kilometres below the surface.
Papua New Guinea lies on "the Ring of Fire", a zone of volcanic activity that accounts for 75 per cent of the world's active and dormant volcanoes.