Magnitude 4.6 Earthquake Near San Jose Shakes Fresno Residents Awake

More than 25,000 Californians filed felt reports with the U.S. Geological Survey before sunrise Thursday after a magnitude 4.6 earthquake near Boulder Creek jolted residents awake at 1:41 a.m., with shaking reaching as far south as King City and as far east as Fresno, roughly 130 miles from the epicenter.

The quake was centered less than a mile outside Boulder Creek in the Santa Cruz Mountains, about 27 miles southwest of San Jose, and is believed to have originated on or near the San Andreas Fault. It was initially recorded at 4.9 before USGS downgraded it to 4.6 by 3 a.m. No damage was reported anywhere along the shaking corridor and no tsunami warning was issued.

Fresno's distance from the epicenter did not spare the city entirely. The Central Valley's alluvial soils, deep layers of sediment deposited over millennia by the San Joaquin River and its tributaries, can amplify seismic waves from distant earthquakes, which is why residents more than two hours from Boulder Creek still felt the movement.

The USGS is projecting a 56% probability of at least one magnitude 3 or higher aftershock within the next seven days, with up to nine such events possible. The agency notes its forecast is most volatile in the first 72 hours after a mainshock and that magnitude 3 tremors are strong enough to be felt by people near the source. Fresno households that felt the pre-dawn shake should expect the possibility of smaller follow-on tremors through at least mid-April.

For anyone unsettled enough to do a walkthrough before work, look for fresh cracks in drywall, shifted door frames, or movement in brick chimneys, particularly in older homes built before California's modern seismic codes. In garages and utility closets, check that water heaters are strapped to wall studs; approved double-strap kits run about $30 at hardware stores throughout the Central Valley and are among the most cost-effective retrofits available to renters and homeowners alike. Tall furniture, bookshelves, and freestanding cabinets should be anchored with L-brackets if they are not already.

For early warnings on future earthquakes, the state's ShakeAlert system delivers alerts through the free MyShake app, developed by UC Berkeley. The app pushes a notification seconds before shaking arrives, which is often enough time to drop and take cover. Wireless Emergency Alerts are also sent automatically to cellphones in affected areas with no app required.

Fresno County residents looking to build or refresh a household emergency kit can find guidance at FresnoCountyCA.gov/Resources/Fresno-County-Emergency. The City of Fresno's Emergency Preparedness Office maintains its own resource at Fresno.gov/citymanager/emergency-preparedness-office. A baseline Central Valley kit covers three days: one gallon of water per person per day, shelf-stable food, a flashlight with spare batteries, a battery-powered emergency radio, and a basic first-aid kit.

The next countywide drill is the Great California ShakeOut on October 15, 2026, at 10:15 a.m. Schools, workplaces, and households in Fresno County can register at ShakeOut.org to practice drop, cover, and hold on before the fault gives less notice than it did Thursday.