The quake's epicenter was 127 kilometers (79 miles) east of Petropavlovsk-Kamchatsky and it struck at 6:58 a.m. Friday local time, according to the USGS. It had a depth of 19.5 kms.
The Pacific Tsunami Warning System briefly issued a tsunami threat but later lifted it.
The initial quake was followed by a series of aftershocks of up to magnitude 5.8.
The remote Kamchatka region has been hit by a series of powerful earthquakes over the past two months, including ones of magnitude 8.8, and two of magnitude 7.4.