The U.S. Geological Survey and Japan's Meteorological Agency estimated the temblor just off the Kamchatka Peninsula to be about 7.7 magnitude. Russia's north Pacific coast is on a major tectonic plate and frequently is hit by earthquakes and volcanic eruptions.
The quake hit at around 12:30 p.m. Friday (2330 GMT Thursday) in the Koryak region, nearly 4,350 miles east of Moscow and some 625 miles north of the largest city in the area, Petropavlovsk-Kamchatsky, said Oleg Kotosanov, a duty officer with the regional emergency department.
It was followed by a series of smaller temblors, including one with a magnitude of 6.1 that was registered five hours later, the USGS said.
Still, the damage appeared to be minimal.
"It is either a wall cracked, or part of the roof, or a porch collapsed," Koryak emergency official Alexander Shchayev told The Associated Press.
While there have already been three major tremors and a number of smaller ones, he noted, "there have not been any reports of the loss of life."
Fourteen villages, with more than 11,800 residents altogether, were affected, said Yulia Stadnikova, spokeswoman for the federal Emergency Situations Ministry. Thirty-one people were injured, including seven who were hospitalized, she said.
Damaged buildings included a school, two nursery schools and residential buildings, another ministry spokesman said. The ITAR-Tass news agency said many residents of the region, where temperatures were minus 18 Celsius, were afraid to return to their homes and had made bonfires to warm themselves and to cook.