4.2 Magnitude Earthquake Triggers Swarm Felt Across the Bay Area

A swarm of earthquakes struck near San Ramon early Monday morning, led by a magnitude 4.2 quake that was felt across the Bay Area, according to the U.S. Geological Survey (USGS).

Following the magnitude 4.2 earthquake, multiple aftershocks were recorded in the region, including at least five earthquakes of magnitude 3.0 or higher, according to the USGS.

The magnitude 4.2 earthquake was recorded at 7:01 a.m. on February 2, with an epicenter located about 4 kilometers southeast of San Ramon. The quake had a depth of 9.6 kilometers, and shaking was felt across the Bay Area, with 4,983 people submitting reports through the USGS “Did You Feel It?” system.

Notable quake, preliminary info: M 4.2 – 4 km ESE of San Ramon, CA https://t.co/dmazcOAcid

— USGS Earthquakes (@USGS_Quakes) February 2, 2026

Communities close to the epicenter felt the tremors of the quake, including Hayward, where Level III shaking was recorded, and Oakland and San Francisco, where Level II shaking was reported.

The earthquake reached a maximum intensity of Level IV near San Ramon, where it was felt by many people but caused no significant damage, according to the USGS.

At this level of shaking, hanging pictures may swing, and light objects can move slightly, according to the USGS.

Two additional earthquakes of magnitude 3.8 were recorded south-southeast of San Ramon on February 2, including one shortly before the magnitude 4.2 event at around 6:27 a.m., and another at 7:27 a.m.

Notable quake, preliminary info: M 3.9 – 4 km SE of San Ramon, CA https://t.co/dB9adLJpHj

— USGS Earthquakes (@USGS_Quakes) February 2, 2026

In addition, several smaller earthquakes ranging between magnitudes 1.3 and 1.8 were recorded on February 2 and 3.

Following the main earthquake, a series of aftershocks occurred in the area in what seismologists describe as an earthquake swarm, where many earthquakes happen close together in time and location.

The USGS released an aftershock forecast on February 3, outlining probabilities for continued seismic activity through February 10.

According to the forecast, there is a 68% chance of magnitude 3.0 or higher aftershocks occurring over the next week, with most scenarios estimating zero to five such events. The probability of magnitude 4.0 or higher aftershocks is 12%, and a magnitude 5.0 or larger earthquake is estimated at 1%.

While these probabilities remain low, USGS cautioned that swarm behavior is complex and more difficult to forecast than standard aftershock sequences. Forecasts may change as new data becomes available, particularly during the first few days after the initial quake.

As aftershocks continue, officials are urging residents to remain prepared and alert. Standard earthquake safety guidance remains in effect. 

People are advised to Drop, Cover, and Hold On during shaking and to stay aware of their surroundings as seismic activity in the area gradually decreases over time.