An earthquake struck the San Francisco Bay Area early Thursday morning, April 2, 2026, waking up residents across a wide swath of Northern California.
The quake hit at 1:41 a.m. local time and was initially reported as a 4.9 magnitude by the United States Geological Survey before being downgraded to 4.6 by around 3 a.m. as seismologists reviewed the data.
No major damage has been reported. No injuries have been reported. Items fell off shelves at a drug store in Boulder Creek, near the epicenter, but emergency responders found nothing structurally significant.
Where It Struck And How Deep
The epicenter was located approximately one kilometer east-southeast of Boulder Creek, an unincorporated community in the Santa Cruz Mountains in Santa Cruz County.
Boulder Creek sits roughly 30 minutes north of the city of Santa Cruz and about an hour south of San Francisco.
The USGS recorded the depth at approximately 6.2 miles, a relatively shallow quake.
Shallow earthquakes are felt more intensely over a wider area than deeper ones because the seismic energy has less distance to travel before reaching the surface.
NBC Bay Area reported the quake is believed to have originated on or near the San Andreas Fault, which runs through the Santa Cruz Mountains in this area.
The San Andreas is the primary fault boundary between the Pacific Plate and the North American Plate and has been responsible for some of the most destructive earthquakes in California history, including the 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake, whose epicenter was also in the Santa Cruz Mountains.
How Many People Felt The Earthquake?
The shaking traveled an impressive distance for a quake of this size. According to USGS Did You Feel It reports and media accounts, residents reported feeling the earthquake as far north as Sacramento and Petaluma, as far south as King City, and there were some reports from Fresno.
Over 24,000 people had filed Did You Feel It reports as of early Thursday morning.
In the immediate Bay Area, ABC7 viewers reported feeling it in Richmond, Mountain View, Hayward, Pacheco, Oakland, and San Francisco. In the South Bay, residents in San Jose, Los Gatos, and Santa Clara felt it.
The Berkeley Scanner reported residents in Burlingame, San Ramon, Fremont, Milpitas, Walnut Creek, Pleasant Hill, San Leandro, Dublin, and Berkeley felt weak to light shaking.
One of the more notable details to emerge from social media in the minutes after the quake was how many people reported their phones warning them before the shaking started, a function of California’s ShakeAlert early warning system, which the USGS confirmed was activated for this event.
ShakeAlert And The UC Berkeley Warning
ShakeAlert is an earthquake early warning system operated by the USGS that detects the initial, faster-moving seismic waves from an earthquake and sends alerts to phones and devices in the affected area seconds before the slower, more destructive shaking arrives.
The window is small, often just a few seconds, but enough to drop to the floor, move away from windows, or brace for impact.
UC Berkeley sent its own alert to campus subscribers at 1:41 a.m. through its MyShake-powered WarnMe system, “An earthquake of initial magnitude 5.1 was detected at or near Boulder Creek, CA, with expected shaking in Berkeley. Please drop, cover, and hold on if you feel shaking.”
Shortly before 2:20 a.m., UC Berkeley issued an all-clear, “There has been minimal impact on campus, and no damage has been reported. Aftershocks are possible.”
The initial Berkeley alert used a preliminary magnitude of 5.1, the magnitude estimates fluctuated in the first hour as more seismograph data was processed, ranging from 5.1 down to 4.9 and ultimately settling at 4.6.
What Have First Responders Found?
CAL FIRE CZU, the unit that covers Santa Cruz and San Mateo counties, enacted its standard earthquake procedure after the quake and inspected all buildings in its jurisdiction.
In a post on X shortly after 2 a.m., it reported, “No damage has been detected.” No other emergency agencies in the broader Bay Area reported structural damage, utility outages, or injuries as of early Thursday morning.
The only physical evidence of note came from Boulder Creek itself, where items reportedly fell off shelves at a local drug store.
No other reports of property damage emerged from the area closest to the epicenter.
What Can We Expect Next?
The USGS published an aftershock forecast shortly after the quake. According to the forecast, there is a 60 percent chance of a magnitude 3.0 or higher aftershock occurring within the next seven days, and a 14 percent chance of a magnitude 4.0 or higher quake in the same window.
The agency noted that up to nine magnitude 3.0 or higher aftershocks are possible, and that the number will decrease over time, though a larger aftershock can temporarily increase activity.
“There will likely be smaller aftershocks within the next week,” the USGS said. “Magnitude 3 and higher aftershocks are large enough to be felt nearby. The number of aftershocks will decrease over time, but a large aftershock can temporarily increase the number of aftershocks.”
Residents near the Boulder Creek epicenter are advised to inspect their properties in daylight for cracked drywall, compromised masonry, or minor structural movement.
Homeowners with chimneys in particular should check for brick damage before using a fireplace.
Bay Area Earthquake Context
The Santa Cruz Mountains have a well-documented history of seismic activity. The 1989 Loma Prieta earthquake, which struck at magnitude 6.9 during Game 3 of the World Series and killed 63 people, was centered in the same mountain range, near the community of Aptos approximately 10 miles south of Thursday’s epicenter.
That quake caused the collapse of a section of the Bay Bridge, the double-deck Cypress Street Viaduct in Oakland, and widespread damage in San Francisco’s Marina District.
Thursday’s earthquake at 4.6 magnitude falls well below the threshold for that kind of destruction.
A 4.6 is strong enough to wake people up, rattle dishes, and knock lightweight objects off shelves, which is exactly what happened, but modern California construction standards, significantly upgraded after Loma Prieta, are designed to withstand substantially larger events without structural failure in most residential and commercial buildings.
The ShakeAlert system that activated overnight is the culmination of decades of scientific work following Loma Prieta. California, Oregon, and Washington all use the system.
Its performance during Thursday’s quake, sending alerts to residents seconds before shaking arrived, reflects exactly the kind of preparedness infrastructure that Bay Area emergency planners have built since 1989.
Residents who felt the quake can file their own report at the USGS Did You Feel It portal at earthquake.usgs.gov.
