A magnitude 4.6 earthquake struck Northern California early Thursday morning, jolting residents awake across a wide area, including parts of the San Francisco Bay Area.

The tremor occurred at approximately 1:40 a.m. local time and was centered just 1.6 kilometers from Boulder Creek, in the Santa Cruz Mountains, according to the U.S. Geological Survey.

The shaking was felt across a 161-kilometer stretch, with reports coming in from multiple cities, including San Francisco and as far north as Petaluma.

Residents Awakened by Sudden Jolt

Many residents reported being abruptly awakened during the night, describing a short but noticeable shaking that lasted a few seconds.

In several cases, people said they first received emergency alerts on their phones before feeling the ground move beneath them. Moments later, beds, windows, and household items began to shake.

The quake’s epicenter, near Boulder Creek, is located in a mountainous region known for frequent seismic activity.

No Immediate Damage Reported

Despite the widespread shaking, there have been no immediate reports of serious damage or injuries.

Authorities continue to monitor the situation, but initial assessments suggest the earthquake caused minimal impact beyond the brief disruption and concern among residents.

Region Known for Frequent Seismic Activity

Northern California, particularly the Bay Area, is no stranger to earthquakes.

In February, a series of smaller quakes rattled the region, including a magnitude 4.2 event south of San Ramon. That sequence included more than a dozen smaller tremors in what experts describe as an “earthquake swarm.”

Seismologists note that such swarms—clusters of minor earthquakes occurring over a short period—have been recorded in the region for decades.

Ongoing Monitoring by Experts

Experts emphasize that while this latest quake was moderate in size, it serves as a reminder of the constant seismic risk in California.

The complex network of fault lines beneath the region means that earthquakes can occur at any time, often without warning.

Authorities encourage residents to remain prepared and to review earthquake safety procedures, including securing heavy objects and knowing safe shelter areas inside homes.