EUREKA, Calif.: A powerful offshore earthquake that struck near the Northern California coast left a hodgepodge of debris for communities to sort through Sunday but spared residents any serious injury.

The 6.5 magnitude temblor hit at about 4:27 p.m. PST Saturday and was centered in the Pacific about 22 miles west of Ferndale. It was felt in towns more than 300 miles south into central California and as far north as central Oregon, the US Geological Survey said. Ferndale is about 240 miles north of San Francisco.

Dozens of people suffered minor injuries and thousands lost power.

More than a dozen aftershocks, some with magnitudes as powerful as 4.5, rumbled for several hours after the initial quake, which had a depth of nearly 10 miles.

Authorities on Saturday said no major injuries were reported. But several people received minor cuts and scrapes from broken glass at the Bayshore Mall in Eureka, and an elderly person fell and broke a hip, authorities said.

"We're mostly getting reports of bumps, bruises and hits on the head," said Laurie Watson Stone, a spokeswoman for St. Joseph Hospital, a 146-bed hospital in Eureka.

Pacific Gas & Electric Co. spokesman J.D. Guidi said power outages were widespread across most of Humboldt County, affecting about 25,000 customers. Nearly 10,000 remained without power some five hours after the quake, and some could remain without power through Sunday, said PG&E spokeswoman Janna Morris.

Eureka city spokesman Gary Bird said because the earthquake hit shortly before dark, only the city's old town received thorough surveys for damage. Authorities there found fallen bricks and parapets that had fallen off old structures, causing damage to adjacent buildings, he said.

"There are some frayed nerves, but I think we've come through this pretty well for the magnitude of earthquake we've had," Bird said.

California is one of the world's most seismically active regions. More than 300 faults crisscross the state, which sits atop two of Earth's major tectonic plates, the Pacific and North American plates. About 10,000 quakes each year rattle Southern California alone, although most of them are too small to be felt.