The first quake, which hit at 2.07 pm (0107 GMT) was centred 85 km south-east of Hihifo, Tonga, and 377 km from American Samoa, which was hard hit by tsunamis triggered by a magnitude-8.0 earthquake on Tuesday.
The epicentre of the second quake, which occurred 48 minutes later, was located 190 km west-south-west of Apia, the capital of the island state of Samoa which was also devastated by Tuesday's quake.
Both quakes were at a shallow depth of 10 km but there were no immediate reports that they had set off a tsunami in the region.
Residents remain afraid of further disasters in the two Samoan states and Tonga, where the combined death toll from the earlier quake reached at least 155.
(Published 02 October 2009, 05:56 IST)
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