The quake struck at 1:15 p.m., according to the USGS. Its epicenter was located about 170 miles west of Bandon and 250 miles west-southwest of Salem, at a depth of 6 miles.
There were no immediate reports of injuries or damage.
The U.S. National Tsunami Warning Center said a tsunami was not expected.
A person who answered the phone at the front desk of the Best Western Inn at Face Rock, in Bandon, said the quake was not felt there.
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The USGS initially measured the quake's magnitude as 6.1 before it was downgraded to 6.0.