HOOPA VALLEY INDIAN RESERVATION, Calif. - A moderate earthquake struck Northern California's coast Monday afternoon, rattling nerves around the Oregon border but yielding no immediate reports of major injuries or damage.

The magnitude-5.6 quake struck at 1:07 p.m. about 18 miles (30 kilometres) east of Trinidad, in an unincorporated part of Humboldt County, the U.S. Geological Survey said. The epicenter was a rural area near the small community of Weitchpec on the Hoopa Valley Indian Reservation, about 240 miles (350 kilometres) north of San Francisco and about 60 miles (96 kilometres) south of the Oregon border.

The temblor was widely felt within a 100-mile (160-kilometre) radius, but the National Oceanic and Atmospheric Administration said it wasn't large enough to generate a tsunami.

The Humboldt County Sheriff's Department and Eureka Police Department sent deputies and officers to check on residents, but dispatchers said there were no immediate reports of emergencies. Things also seemed fine on the Hoopa reservation, according to Byron Nelson Jr., the tribe's vice chairman.

"It was just a mild shaking. It wasn't a sharp jerk," said Sgt. Gene McManus of the Del Norte County Sheriff's Department, a neighbouring agency that also saw no immediate problems.

Children's building blocks tumbled at Weitchpec Elementary School, but the staff and students took the shaking in stride.

Kate Lowry, the school's sole teacher, told The Associated Press in a phone interview that she, her aide and the 19 children followed their earthquake drill procedure and filed out of the building.

"We were still moving as we were walking across," Lowry said. "Once we got down in the field, it had stopped."

At nearby Pearson's Grocery Store, Karen Pearson watched cans fall off the shelves as a man yelled for people to get out.

"It was very scary because you have no control of these things," Pearson said. "Hopefully it's over."