QuakeIndex

Earthquake · reviewed by a seismologist

M 2.5md

Earthquake near Alamo, CA

No earthquake was likely felt in Alamo in the 24 hours to 2:31 pm PST (22:31 UTC). The last one was M 2.1, 11 km (7 mi) NNW, at 4:05 am PST on 8 November 2026, estimated intensity II (weak) in town; 3 felt reports to USGS. Every earthquake near Alamo

This page: a magnitude 2.5 earthquake was recorded 4 km (3 mi) west-southwest of Alamo, CA, at 4:45 am PDT on 12 March 2025 (11:45 UTC), 6.0 km deep. 39 people have reported feeling it to USGS.

USGS: 4 km W of Alamo, CA

15 km (9 mi) ENE of Oakland, CA · 8 km (5 mi) SSW of Walnut Creek, CA

4:45 am PDT, Mar 12, 2025 · · 6.0 km deep · released about 150 lb of TNT

Every earthquake near Alamo Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 14 kmAlameda County 26 kmSolano County 49 kmSan Mateo County 54 kmMarin County 63 kmSan Joaquin County 71 kmSanta Clara County 77 kmNapa County 77 kmSan Francisco County 85 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
4:45 am PDT on 12 March 2025 ()
Where
4 km (3 mi) west-southwest of Alamo, CA · earthquakes near Alamo
Magnitude
M 2.5 (md)
Depth
6.0 km below the surface
Felt
39 reports · strongest reported intensity IV
Nearest
Contra Costa County, 14 km NE
Nearest mapped fault
Calaveras fault, 4 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 544 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 21 km (13 mi) from the epicentre. In Alamo, 4 km away, the estimate is intensity III (weak). 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: Alamo 4 km, intensity III · Lafayette 6 km, intensity III · Danville 7 km, intensity III · Walnut Creek 8 km, intensity III · Orinda 10 km, intensity II · San Ramon 11 km, intensity II · Pleasant Hill 12 km, intensity II · San Leandro 14 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 150 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 100,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 72,000× the energy of this one
  3. Around the size people start to feel M 3.0 6.5× the energy of this one
  4. This earthquake M 2.5 about 150 lb of TNT

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 1,000 times the energy of this one.

Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.9 The 1906 San Francisco, California Earthquake · 43 km WSW of this epicentre
  2. 6.0 The 2014 South Napa, California Earthquake · 47 km NNW of this epicentre
  3. 5.8 The 1980 Livermore, California Earthquake · 27 km E of this epicentre
  4. 5.4 9 km NE of Livermore, California · 34 km ESE of this epicentre
  5. 5.3 The 1957 San Francisco, California Earthquake · 40 km WSW 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 37.8392, -122.0773. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Contra Costa County, CA 14 km (9 mi) NE earthquakes near Contra Costa County
Alameda County, CA 26 km (16 mi) SE earthquakes near Alameda County
Solano County, CA 49 km (31 mi) NNE earthquakes near Solano County
San Mateo County, CA 54 km (33 mi) SSW earthquakes near San Mateo County
Marin County, CA 63 km (39 mi) WNW earthquakes near Marin County
San Joaquin County, CA 71 km (44 mi) E 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 SW of Alamo, CA
  2. 2.1 5 km ENE of Vallejo, CA
  3. 1.6 9 km NE of Milpitas, CA
  4. 2.1 1 km ESE of Union City, CA
  5. 1.8 2 km ESE of Union City, CA
  6. 2.8 1 km ESE of Union City, CA
  7. 1.7 5 km NNW of Orinda, CA
  8. 1.6 2 km SW of Clayton, CA
  9. 1.7 5 km E of Vallejo, CA
  10. 2.1 1 km NNW of San Pablo, CA
  11. 2.4 1 km NNW of San Pablo, CA
  12. 1.5 1 km of San Pablo, CA
  13. 1.6 8 km NNE of Livermore, CA
  14. 1.8 9 km NNE of Livermore, CA
  15. 1.5 9 km NNE of Livermore, 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.