A 7.9 magnitude earthquake about 200km (130 miles) south-east of Tonga has triggered a tsunami in the South Pacific, but no damage is reported.
The quake hit at 0618 local time (1818 GMT) at a depth of 10km (6.2 miles).
The tremor, which residents from Fiji to New Zealand reported feeling, was followed two hours later by an after-shock of 5.3 magnitude.
A regional tsunami warning was issued, but withdrawn just over an hour and a half later.
'Got off lightly'
A resident of the Tongan capital Nuku'alofa said there was no sign of significant damage or of a tsunami after the shallow quake.
Caroline Holden, a seismologist with New Zealand's Institute of Geological and Nuclear Sciences, said this was surprising.
"Quite remarkable, given the magnitude of it. We might have gotten off lightly," the national police commander, Chris Kelly, said.
An undersea volcano has also been erupting off the coast of Tongatapu
"The house really moved, the trees were swaying and the ground was rippling," he said.
People in low lying areas of Fiji fled for higher ground, officials said, and schools and government offices were closed.
New Zealand seismologist Craig Miller said "a long, low rolling motion" from the quake was reported by residents on the east coast of New Zealand's North Island - more than 3,000 km (1,875 miles) from the quake's epicentre.
Tonga resident Pesi Fonua told the Associated Press the quake had lasted for "something like 20 seconds" but he had seen no damage.
Police spokesman Niua Kama told the agency residents did not appear to take the warning seriously.
"People are out on the roads, laughing at the warning," he said.
They were not moving back from the coast despite tsunami warnings, the spokesman added.
Several earthquakes have been felt in Tonga recently and an undersea volcano has been erupting off the coast of the main island Tongatapu, although it was not considered to be a threat to people in the area.
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