Quake swarm with magnitude 4.2 tremor rattles Bay Area, seismologists say

A magnitude 4.2 earthquake shook the San Ramon area on Monday, Feb. 2, according to the U.S. Geological Survey.

The 6-mile deep quake hit 2 miles from San Ramon at 7:01 a.m. Monday, the U.S. Geological Survey said on its website.

More than 4,000 people — some as far away as Livermore and Oakland — reported feeling the tremor to the agency.

“This was my first earthquake experience. 10/10 would not recommend,” Anand Nanduri wrote in an X post on Monday.

“O good morning to you earthquake,” another X user wrote.

“Another quake, wow,” X user Andy Sanchez wrote. ”This is concerning much, I’m nervous.”

The quake was preceded by a swarm of smaller quakes ranging from magnitude 2.5 to 3.9 beginning at 6:27 a.m.

San Ramon has been hit by swarms of hundreds of earthquakes since November.

What to know about earthquakes

Magnitude measures the energy released at the source of the earthquake, the U.S. Geological Survey says. It replaces the old Richter scale.

Earthquakes between magnitudes 2.5 and 5.4 are often felt but rarely cause much damage, according to Michigan Tech. Quakes below magnitude 2.5 are seldom felt by most people.

Earthquakes’ sudden, rapid shaking can cause fires, tsunamis, landslides or avalanches. They can happen anywhere, but they’re most common in Alaska, California, Hawaii, Oregon, Puerto Rico and Washington, according to the U.S. Department of Homeland Security.

How to stay safe during an earthquake

If an earthquake strikes, it’s best to protect yourself right away, the Department of Homeland Security said. Here are tips from experts:

• If you’re in a car: Pull over and stop. Set your parking brake.
• If you’re in bed: Turn face-down and cover your head with a pillow.
• If you’re outdoors: Stay away from buildings. Don’t go inside.
• If you’re inside: Stay and don’t run outdoors. Stay away from doorways.

The best way to protect yourself during an earthquake is to drop, cover and hold on, officials say.

“Wherever you are, drop down to your hands and knees and hold onto something sturdy,” officials say. “If you’re using a wheelchair or walker with a seat, make sure your wheels are locked and remain seated until the shaking stops.”

Be sure to cover your head and neck with your arms, and crawl under a sturdy table if possible. If no shelter is available, crawl to an interior wall away from windows.

Once under a table, officials say you should hold on with one hand and be ready to move with it.

“There can be serious hazards after an earthquake, such as damage to the building, leaking gas and water lines, or downed power lines,” officials say. “Expect aftershocks to follow the main shock of an earthquake. Be ready to Drop, Cover, and Hold On if you feel an aftershock.”

This story was originally published February 2, 2026 at 7:59 AM with the headline "Quake swarm with magnitude 4.2 tremor rattles Bay Area, seismologists say."