BOULDER CREEK, Calif. (AP) — An earthquake of magnitude 4.6 in Northern California awakened residents with a jolt early Thursday, with many saying they felt their homes shake for a few seconds in a 100-mile (161-kilometer) stretch, including San Francisco.

The earthquake was centered a mile (1.6 kilometers) from Boulder Creek in the Santa Cruz Mountains, the U.S. Geological Survey reported. It happened at about 1:40 a.m.

There were no immediate reports of serious damage.

Boulder Creek, which has about 5,000 people, is about 65 miles (105 kilometers) southeast of San Francisco. Residents as far north as Petaluma, about 40 miles (64 kilometers) north of San Francisco, also said they felt it.

More than 25,000 impact reports have been filed with the survey.

“There are on the order of 50 earthquakes a day in California. These magnitude earthquakes don’t happen very frequently, but they happen frequently enough that there are these reminders that we do live in earthquake country,” Robert de Groot, a physical scientist with the U.S. Geological Survey Earthquake Science Center, told KGO-TV.

Some residents said they were first awakened by earthquake alerts on their phone, then felt their beds and windows shake. Some items were knocked off store shelves in Boulder Creek.

In February, a series of small earthquakes rattled the San Francisco Bay Area. The most powerful quake was a magnitude 4.2 that struck south of San Ramon, according to the USGS.

At least a dozen other smaller quakes struck in the same area.

The area east of San Francisco has experienced earthquake swarms — when multiple small magnitude earthquakes strike over a short period of time — for decades, according to seismology experts.