A 6.2 magnitude quake shakes Northern California on Monday

A 6.2 magnitude earthquake struck offshore in the Cape Mendocino area of Northern California, followed by aftershocks that rattled nerves and caused items to fall from shelves, authorities said Monday.

No major damage or injuries were reported.

The quake struck at a depth of 5.6 miles in the Pacific Ocean about 24 miles west of the tiny community of Petrolia along the rocky wilderness of California’s Lost Coast region in Humboldt County, the United States Geological Survey and the Humboldt County Sheriff’s Department said.

The quake did not trigger a tsunami warning because of the nature of the fault system from which it came, seismologist Lucy Jones posted on Twitter.

No injuries were immediately reported after the quake struck at 12:10 p.m. local time, Humboldt County Sheriff’s Department spokeswoman Samantha Karges said in an email. No evacuations have been ordered in the sparsely populated region.

Workers and crews were deployed to check for damage to roadways, and two roads were closed due to rock slides caused by the shaking, Karges said. In the southern part of the county, numerous aftershocks were recorded along the coast, her department said on Twitter.

A scientist in San Francisco felt the shaking about 200 miles (320 km) away, the California Geological Survey posted on Twitter.

“Moderate to strong shaking was recorded by the seismic network along the coast,” a posting on the agency’s Twitter feed said. “The earthquake was felt in San Francisco by this CGS geologist!”

In 1992, the same region was rattled by a series of earthquakes that damaged more than 1,100 homes and businesses, the Los Angeles Times reported later that year.

The largest of the 1992 quakes measured 7.2, about 10 times the magnitude of Monday’s quake.

Early warning system worked

California's early earthquake warning system worked for those who are signed up for alerts to their mobile devices. Honsal said he received the alert about 10-15 seconds before feeling the earth shake.

The state's Office of Emergency Services is "actively monitoring" and "coordinating closely with local partners in the region to protect communities from any secondary impacts," the agency tweeted.

Humboldt County is sparsely populated, with about 135,000 residents spread over about 4,000 square miles. The area is near the California/Oregon border, about 270 miles north of San Francisco.