Jan. 22 (UPI) -- A 7.9-magnitude earthquake struck the South Pacific's Solomon Islands and Papua New Guinea on Sunday but no injuries were reported.
The quake, which had a depth of over 84 miles, was centered on Bougainville Island, an island of approximately 175,000 people, which is geographically part of the Solomon Islands chain but is not part of island's government, the U.S. Geological Survey states.
The quake, which was 25 miles northwest of Panguna, hit at 4:30 a.m.
Two hours later, the Pacific Tsunami Warning Center canceled tsunami threats for Papua New Guinea and the Solomon Islands.
The earthquake was downgraded from 8 by USGS.
Two smaller quakes -- measuring 5.6 and 4.6 -- struck nearby shortly afterward, USGS said.
USGS computer models estimate that some 570,000 people on nearby islands may have felt the earthquake, including 234,000 people who may have experienced "very strong" to "severe" shaking.
"Overall, the population in this region resides in structures that are vulnerable to earthquake shaking, though some resistant structures exist," the USGS said. "Overall, the population in this region resides in structures that are vulnerable to earthquake shaking, though some resistant structures exist."
No casualties were reported but damage was in parts of central Bougainville and the major town of Arawa, Aloysius Laukai, -- manager of New Dawn FM Bougainville radio station -- said in an email to 9News in Australia. The provincial capital of Buka was blacked out.
The Autonomous Region of Bougainville was previously known as the North Solomons Province.
The Solomon Islands are part of Pacific Ring of Fire.
On Dec. 8, a 7.7-magnitude earthquake struck 42 miles southwest of Kirakiraoff in the Solomon Islands.
Solomon Islands, about 2,000 miles from Australia, is a sovereign country of six major islands and more than 900 smaller islands in Oceania. The islands' population was estimated at 523,000 in a 2009 report by the United Nations.
Queen Elizabeth II is the British monarchy head of state. The Solomon Islands earned independence from Britain in 1978.