Series of minor earthquakes shakes California over past week

California experienced a string of separate, relatively minor earthquakes over the past week, rattling different regions of the state without causing reported damage or injuries.

Ontario, San Bernardino County

The first struck around 5:37 a.m. on September 2 near Ontario, according to ABC7. The U.S. Geological Survey (USGS) measured it at magnitude 3.4, at a depth of nearly 4 miles. Residents in Fontana and Chino said they were woken by the shaking. No damage or injuries were reported.

Santa Rosa area, Northern California

On September 3, shortly after 10:30 a.m., another quake struck near Larkfield-Wikiup, north of Santa Rosa. The USGS initially reported the magnitude as 3.5 before revising it down to 3.3, as both The Press Democrat and Patch reported. The quake originated about 4.6 miles below the surface. Shaking was felt across a wide area — from Santa Rosa, Rohnert Park and Cotati to as far as Hayward and Petaluma, more than 20 miles from the epicenter. Several schools, including Santa Rosa High School, were evacuated as a precaution, though no early dismissals were ordered and buildings were found safe. No damage was reported. The quake occurred near the Rodgers Creek Fault, part of the Hayward-Rodgers Creek fault system capable of producing major earthquakes — magnitude 5.6 and 5.7 quakes hit the area in 1969, causing significant damage, and 4.3-4.4 magnitude quakes damaged homes there in 2022. Sonoma County emergency management spokesperson Karen Hancock said the quake was too small to trigger USGS's ShakeAlert or UC Berkeley's MyShake early-warning systems, which generally activate for magnitude 4.5 or greater events.

Compton, Los Angeles County

Just after midnight on September 6, at 12:13 a.m., a preliminary magnitude 3.2 quake struck near Compton, about 6.1 miles north of Long Beach, the Orange County Register reported. It occurred at a depth of about 8 miles. Residents in Los Angeles, La Habra, Seal Beach, Bell and La Mirada reported feeling it, with more than 620 people submitting USGS felt reports describing weak shaking. It was the second quake to hit the broader area recently — a magnitude 3.4 quake had struck near Ontario just days earlier, on September 2.

None of the events resulted in confirmed structural damage or casualties. The quakes coincided with National Preparedness Month in the U.S., prompting local officials to urge residents to review their emergency plans.