Updated 1:27 p.m. ET
A strong earthquake struck the Tonga region of the South Pacific early this morning at 4:26 local time, according to the U.S. Geological Survey.
The most recent bulletin put the quake's magnitude at 7.8. It had ranged as high as 8.1 in earlier reports.
The Pacific Tsunami Warning Center issued a warning for Fiji and New Zealand, but initial reports indicate that no tsunami was generated by the quake.
Not all earthquakes on the seafloor cause tsunamis. To make a wave, a fault must rupture in a way that causes the seafloor to lift up and act as a paddle. This event originated some 20 miles below the seafloor and did not appear to be the type that would create a significant tsunami, scientists said.
The 7.8-rating is still preliminary and could be revised later in the day.
The Kingdom of Tonga is an archipelago nation located in the South Pacific Ocean, about a third of the way between New Zealand and Hawaii, east of Fiji. Tonga sits atop one of the most earthquake-prone regions in the world, where the Pacific Plate and Australia-India plate come together.
A magnitude 7.6 earthquake struck the region on March 9, 1994.
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