13 Apr ‘It’s in the Back of My Mind’: San Ramon Teens React to Earthquake Swarm

A 4.0-magnitude earthquake struck three miles southeast of San Ramon on Dec. 20, 2025, following 3.8- and 4.0-magnitude quakes in the area the previous night, according to the U.S. Geological Survey. San Ramon is experiencing a monthslong earthquake swarm. (Google Maps via Bay City News)

Editor’s note: The author of this article is a high school student in San Ramon.

By Anushka Devananthan

San Ramon has experienced several earthquakes in recent months, including a magnitude 4.2 quake Feb. 2 that left residents shaken.

While many of the recent earthquakes had been minor, the Feb. 2 earthquake was noticeably stronger. The initial jolt felt sharper and lasted several seconds longer than expected. Frames hung on the wall started to slip sideways, while books threatened to fall off shelves. Even after it felt like the shakes stopped, another one appeared a few hours later, leaving residents on edge. As the tremors continued, even small movements like shifting a table would cause people to quickly search if yet another earthquake had recently occurred.

Located along the Calaveras fault, an active branch of the San Andreas fault that led to the massive 1906 San Francisco earthquake, San Ramon and surrounding areas are particularly vulnerable to any seismic activity. Since November, that activity has been heightened, with more than 150 quakes of at least a 2.0 magnitude jarring the town.

Geologists describe what is happening to San Ramon as an “earthquake swarm.”

“In the case of a swarm, there is no identifiable main shock,” said Dr. Angie Lux, a seismologist at the UC Berkeley Seismology Lab. “It just keeps going, ebbing and flowing with no real pattern to what’s happening.”

In contrast, she said, a regular earthquake results in a singular main event with aftershocks in decreasing magnitude.

According to Lux, these swarms occur in a “very complex faulting environment,” where multiple smaller faults handle stress and strain. When the earth’s tectonic plates constantly push and pull, it can create subduction zones where plates are pulled down from the motion of one another. The stress generated from the plate movement emerges as faults, cracks in the ground.

Researchers like Lux have observed that underground fluids moving along these small faults may influence where earthquakes occur, which matches the recent seismic patterns. Additionally, earthquakes themselves can lead to the development of smaller faults.

For many San Ramon residents, the recent earthquakes have become harder to ignore. The question of whether another earthquake of at least 4.0 magnitude could strike continues to arise.

Inika Arya, a sophomore at Dougherty Valley High School, said she was home alone during the Feb. 2 quake.

“My parents weren’t home, and I was upstairs when I experienced the earthquake,” she said. “It wasn’t a big deal for me, but my mom and my dad were very concerned.”

Many students and families have noticed the uptick in earthquakes over the past few months. Some reported objects falling off shelves or being startled while at home.

Inika said that although she had grown accustomed to the earthquakes in the past few months, it still was a moment of concern whenever it happened.

“It made me nervous when doing my work because there was always the concern that another one could happen at any time,” she said.

“Part of me is a little worried just because you never really know how big the next one could be,” said Tanishi Rawal, a junior at Dougherty Valley High School. “I wouldn’t say it’s a constant fear, but it’s definitely in the back of my mind more than before.”

Although researchers are unable to predict when swarms may start or stop, Lux said this particular swarm has been “very energetic,” especially compared to previously active swarms. And it is very possible to have another magnitude 4 earthquake.

“We can’t say why it started, we can’t say when it’s going to stop, we can’t say when it’s going to go again,” Lux said. “It again just has to do with the stress buildup fluid movement. That’s pretty much all we can say at this point.”

To bring awareness to these earthquakes, Lux works on the ShakeAlert earthquake early warning system. Rather than predicting an earthquake, the system detects if an earthquake has already happened and estimates the magnitude and location. It then issues alerts to the public in multiple ways including via cell phone and broadcast. She emphasized the goal is to “warn people further out that they may experience seismic waves” and in response “drop, cover, and hold on to protect yourself from falling objects” when you get that alert.

While these frequent tremors can disrupt daily life,. Lux believes that these swarms can act as a reminder for everyone to prepare themselves for the “next big earthquake.”

“While we don’t necessarily expect a big earthquake right where the swarms are, the Calaveras fault is capable of a large earthquake, and it could potentially start in that area,” Lux said. “Residents should make sure their earthquake kit is put together and that they have all their important documents ready.”

For residents living along the Calaveras fault, earthquakes have become almost a part of daily life. While researchers are unable to determine the likelihood of these swarms ending, students and families face growing concern with the rapid swarms and possibility of a larger earthquake. Until then, residents can prepare themselves through taking preventive measures and staying aware of alerts.

“It’s stressful because I get reminded of how devastating they can be,” Inika said. “I don’t think a big earthquake like that has ever happened in San Ramon, so hopefully that trend continues.”