The quake struck at 10:06 a.m. local time and was centered just over 4 miles southeast of Naalehu, at a depth of 6 miles, the USGS said.
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Some shaking could be felt in Honolulu on the island of Oahu which is about 200 miles to the north.
Whether anyone was seriously injured or any major structural damage occurred was not immediately clear.
The Pacific Tsunami Warning Center said no tsunami was expected.
"Many areas may have experienced strong shaking," from the earthquake that occurred shortly after 10 a.m. local time, the Hawaii Emergency Management Agency posted on X. It also reiterated that there was no threat of a tsunami.
Big Island Mayor Mitch Roth was in Honolulu at a cardiologist appointment. "All of a sudden I felt like I was getting dizzy," he said, thinking at first that it was the procedure and then realizing it was an earthquake. He immediately got on the phone with his emergency management officials.
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"We'll probably start hearing about damage in the next hour to an hour," Roth said, pointing out that it was "a good sized earthquake" and that from what he's heard, there is no tsunami threat.
Roth said he was headed to the Honolulu airport to try to get an earlier flight back to the Big Island.
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Julia Neal, the owner of Pahala Plantation Cottages, said a mirror and brass lamp fell down during some forceful shaking. "We have a lot of the old wooden plantations homes and so they were rattling pretty loudly."
The quake's magnitude was initially measured at 6.3 before being downgraded, according to the USGS.
The Associated Press contributed to this report.