Earthquake San Ramon: Small pre-dawn tremors jolt the East Bay, no damage reported

A string of small earthquakes rippled beneath San Ramon before dawn on Monday, December 8, briefly waking some residents but causing no reported damage or injuries. Initial readings indicate at least two measurable tremors between roughly 2:00 a.m. and 3:15 a.m. Pacific Time, including events around magnitude 2.1–2.2 and another close to magnitude 2.9. The quakes were shallow and centered a couple of miles southeast of San Ramon, a spot that frequently hosts minor seismic flurries.

Latest on the San Ramon earthquake activity

Early readings show a tight cluster of weak-to-light earthquakes:

• Approx. 2:11 a.m. PT: A small quake around M2.1 with a shallow focus near 2 miles SE of San Ramon (about 5 miles deep).

• Around 3:00 a.m. PT: Another minor event close to M2.2 from a similar location and depth.

• Shortly after 3:00 a.m. PT: A slightly stronger tremor near M2.9, felt by more residents in San Ramon, Danville, Dublin, and Pleasanton.

Magnitude estimates can vary slightly in the first hour as analysts refine seismic data. The consistent thread this morning: short, sharp shakes typical of the area’s micro-quakes, with shaking levels too low to generate structural damage.

Where the earthquake hit in San Ramon

The epicentral area lies southeast of central San Ramon, near the I-680 corridor and foothill neighborhoods that sit above strands of the Calaveras Fault, a major branch of the San Andreas system. This fault creeps slowly in places and occasionally releases clusters of small quakes. Because these events were shallow (on the order of several miles deep), some residents reported a quick jolt or a single thump that rattled windows or light fixtures.

What residents felt—and what it means

Most reports describe a brief jolt or light rattle lasting just a second or two. For events in the M2–M3 range, felt shaking depends heavily on how close you are to the epicenter, the depth of the rupture, and local soil conditions. Harder bedrock areas may feel a crisp tap; softer, alluvial ground can amplify motion slightly. In practical terms, these quakes serve as reminders of the region’s active geology rather than as harbingers of immediate larger shocks.

Seismologists note that San Ramon has experienced swarms in the past—dozens of tiny quakes over days to weeks—without leading to damaging events. While a small fraction of swarms precede larger earthquakes, the most common outcome is that activity tapers without escalation. As of this morning, the pattern fits a routine micro-quake sequence.

Earthquake San Ramon: safety steps to take today

Even when shaking is minor, it’s smart to use moments like this to tighten your readiness:

• Secure and store: Strap tall furniture; keep heavy items off high shelves.

• Refresh kits: One gallon of water per person per day (three days), non-perishable food, flashlight, batteries, first-aid supplies, medications.

• Plan communications: Choose an out-of-area contact; text rather than call after a quake.

• Drill the basics: If shaking starts, Drop, Cover, and Hold On until it stops.

• Check gas/electric: Only turn off gas if you smell it or hear a leak; know where your shutoff valves and breakers are.

Why San Ramon gets these small earthquakes

San Ramon sits near the Calaveras Fault, which accommodates a slice of the Bay Area’s plate motion. Parts of this fault exhibit aseismic creep—steady movement without large quakes—interrupted by clusters of small events as stress redistributes. The shallow depth and repeating epicentral locations observed this morning are consistent with that behavior. Nearby faults, including the Hayward-Rodgers Creek system, also shape the region’s seismic character, but today’s tremors align with the Calaveras trend that periodically nudges the Tri-Valley and I-680 corridor.

What to watch next

• Aftershocks: Minor follow-ups are possible, usually smaller than the largest event so far. Most would be in the micro to low-2 range and not widely felt.

• Data updates: Magnitudes and locations may be fine-tuned as additional sensors report in; small revisions are normal.

• Preparedness window: Use the calm between events to review family plans and workplace protocols.

If you felt the earthquake in San Ramon, submitting a brief “felt report” helps refine intensity maps and improves future response modeling. For now, the early-morning sequence appears low-impact, with shaking levels in line with typical East Bay micro-quakes. Daily routines can continue as normal, with a little extra attention to preparedness—wise practice in one of North America’s most closely monitored seismic corridors.