QuakeIndex

Earthquake · reviewed by a seismologist

M 3.8mw

Earthquake near San Ramon, CA

No earthquake was likely felt in San Ramon in the 24 hours to 4:30 am PST (12:30 UTC). The last one was M 2.1, 6 km (4 mi) NNE, at 7:18 am PDT on 31 October 2026, estimated intensity II (weak) in town; 1 felt report to USGS. Every earthquake near San Ramon

This page: a magnitude 3.8 earthquake was recorded 5 km (3 mi) south-southeast of San Ramon, CA, at 7:49 pm PST on 19 December 2025 (03:49 UTC), 9.6 km deep. 1,040 people have reported feeling it to USGS.

USGS: 5 km SSE of San Ramon, CA

in San Ramon, CA · 41 km (26 mi) E of San Francisco, CA

7:49 pm PST, Dec 19, 2025 · · 9.6 km deep · released about 6.8 tons of TNT

Every earthquake near San Ramon Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Alameda County 11 kmContra Costa County 20 kmSan Mateo County 52 kmSolano County 58 kmSanta Clara County 62 kmSan Joaquin County 64 kmMarin County 78 kmSanta Cruz County 81 kmStanislaus County 86 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
7:49 pm PST on 19 December 2025 ()
Where
5 km (3 mi) south-southeast of San Ramon, CA · earthquakes near San Ramon
Magnitude
M 3.8 (mw)
Depth
9.6 km below the surface
Felt
1,040 reports · strongest reported intensity V
Measured shaking
intensity IV (ShakeMap)
Nearest
Alameda County, 11 km SSE
Nearest mapped fault
Calaveras fault, 2 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 325 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 80 km (50 mi) from the epicentre. In San Ramon, 5 km away, the estimate is intensity IV (light). Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.

Likely felt in: San Ramon 5 km, intensity IV · Dublin 5 km, intensity IV · Danville 10 km, intensity III · Pleasanton 11 km, intensity III · Castro Valley 13 km, intensity III · Alamo 14 km, intensity III · Hayward 14 km, intensity III · Union City 17 km, intensity III. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 6.8 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.8 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 25,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 1,100× the energy of this one
  3. Magna, Utah 2020 M 5.7 790× the energy of this one
  4. This earthquake M 3.8 about 6.8 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 14× more

Energy from the Gutenberg–Richter relation (log10E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.

For this area

The largest earthquake within 50 km since 2016 was M 4.5 on 2019-10-15 — about 11 times the energy of this one.

Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.8 The 1980 Livermore, California Earthquake · 20 km ENE of this epicentre
  2. 5.7 15 km NE of East Foothills, California · 38 km SE of this epicentre
  3. 5.5 6 km NNE of East Foothills, California · 38 km SSE of this epicentre
  4. 5.4 9 km NE of Livermore, California · 22 km E of this epicentre
  5. 5.3 The 1957 San Francisco, California Earthquake · 47 km W of this epicentre

Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.

Where

Epicentre 37.7428, -121.9538. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Alameda County, CA 11 km (7 mi) SSE earthquakes near Alameda County
Contra Costa County, CA 20 km (12 mi) N earthquakes near Contra Costa County
San Mateo County, CA 52 km (32 mi) SW earthquakes near San Mateo County
Solano County, CA 58 km (36 mi) N earthquakes near Solano County
Santa Clara County, CA 62 km (39 mi) SSE earthquakes near Santa Clara County
San Joaquin County, CA 64 km (39 mi) ENE earthquakes near San Joaquin County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

60 earthquakes have been recorded within 50 km since this one.

  1. 1.6 5 km SE of San Ramon, CA
  2. 1.7 5 km SE of San Ramon, CA
  3. 1.9 3 km SE of Pacifica, CA
  4. 1.9 3 km ESE of San Ramon, CA
  5. 1.7 4 km ESE of San Ramon, CA
  6. 1.8 5 km S of Blackhawk, CA
  7. 1.7 4 km SE of San Ramon, CA
  8. 1.9 5 km SE of San Ramon, CA
  9. 2.1 5 km SE of San Ramon, CA
  10. 2.5 5 km SE of San Ramon, CA
  11. 2.2 4 km SE of San Ramon, CA
  12. 2.5 4 km ESE of San Ramon, CA
  13. 1.6 5 km SE of San Ramon, CA
  14. 1.9 5 km ESE of Walnut Creek, CA
  15. 1.7 4 km SE of Portola Valley, CA

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of . QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.