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SeismoAtlas

M2.3 earthquake 4 km WNW of Orinda, California, United States

A magnitude 2.3 earthquake struck 4 km WNW of Orinda, California, United States at 10:41 local time (17:41 UTC) on 26 Sept 2026, at a depth of 4 km, according to USGS. The solution is preliminary and may be revised.

2 reports to USGS “Did You Feel It?”

Data: USGS · updated 2026-09-27 02:04 UTC · automatic solution

Magnitude
2.3micro
duration magnitude (md)
Depth
3.9 km
Status
Automatic
Origin time
2026-09-26 17:41:27 UTC
Local: 26 Sept 2026, 10:41:27 (America/Los Angeles)
Epicentre
37.889° N, 122.224° W

Circles show this event and others within 30 km from 7 days before to 30 days after. Lines: plate boundaries and GEM active faults. Open on the live map

Nearby places

Distance and estimated shaking at nearby places
PlaceDistanceEst. shaking
OrindaCalifornia, United States · pop. 19,2794 kmIIIWeak
BerkeleyCalifornia, United States · pop. 120,9725 kmIIIWeak
El CerritoCalifornia, United States · pop. 23,5498 kmIIWeak
LafayetteCalifornia, United States · pop. 25,8439 kmIIWeak
OaklandCalifornia, United States · pop. 419,26711 kmIIWeak
San FranciscoCalifornia, United States · pop. 827,52622 kmINot felt
San JoseCalifornia, United States · pop. 997,36868 kmINot felt
StocktonCalifornia, United States · pop. 305,65882 kmINot felt

Shaking is an estimate from the intensity prediction equation of Allen, Wald & Worden (2012), not an observation. Local ground and buildings can change it by a level or more. Likely felt out to about 7 km.

Every agency's solution

Agencies locate earthquakes with their own stations and methods, so their numbers differ. We match reports of the same event by time, distance and magnitude and show them side by side. The headline uses USGS · NC.

AgencyMagnitudeDepthEpicentreTime offsetStatus
USGS · NCheadlineNorthern California Seismic System via U.S. Geological Survey2.3 md3.9 km37.89° N, 122.22° W–Automatic

How big was it?

Usually not felt. Recorded by nearby seismometers; thousands occur worldwide every day.

It released roughly the energy of 49 kg of TNT. Magnitude is logarithmic: each whole step means about 32 times more energy and 10 times larger waves on a seismogram. Depth matters too: at 4 km this was a shallow earthquake, which is felt more strongly at the surface than a deeper one of the same size.

M2.3 releases about 36× the energy of M1.3, and its waves are about 11× taller on a seismogram. Energy: 49 kg of TNT vs 1 kg of TNT.

Each square is the energy of one M1.3. Energy from log₁₀E = 1.5M + 4.8.

Aftershocks and nearby activity

20 later earthquakes within 30 km; the largest was M2.4 25 days ago. 4 in the 7 days before. Aftershock rates usually fall off roughly in proportion to 1/time.

Aftershocks

Mainshock M2.3

20 later earthquakes nearby. Aftershock rates typically fall off roughly as 1/time (Omori's law).

Aftershocks
Time after mainshock (hours)MagnitudeDepth (km)
17.121.68
52.411.78
118.812.09
203.370.94
212.091.77
217.451.69
386.031.46
409.021.40
419.081.27
419.161.715
523.051.69
534.731.87
535.611.16
536.091.46
536.451.68
536.562.47
536.901.79
557.812.47
707.091.315
709.141.03
  1. 2.4Near San Ramon, California, United States10-19 02:15
  2. 2.44 km SE of San Ramon, California, United States10-19 23:29
  3. 2.03 km ESE of San Pablo, California, United States10-01 16:29
  4. 1.8Near San Ramon, California, United States10-19 00:24
  5. 1.7Near Pleasant Hill, California, United States10-14 04:51
  6. 1.7Near San Ramon, California, United States10-19 02:35
  7. 1.74 km NW of Orinda, California, United States10-05 13:46
  8. 1.7Near San Ramon, California, United States09-28 22:06
  9. 1.6Near Alamo, California, United States10-18 12:44
  10. 1.6Near San Ramon, California, United States09-27 10:48
  11. 1.6Near San Ramon, California, United States10-19 02:08
  12. 1.66 km SW of Clayton, California, United States10-05 19:08
  13. 1.43 km NNE of San Leandro, California, United States10-12 19:43
  14. 1.47 km ENE of San Rafael, California, United States10-13 18:42
  15. 1.4Near San Ramon, California, United States10-19 01:46
  16. 1.35 km SSW of Pittsburg, California, United States10-26 04:46
  17. 1.2Near Alamo, California, United States10-14 04:46
  18. 1.1Near San Ramon, California, United States10-19 01:17
  19. 1.06 km SSW of Moraga, California, United States10-26 06:49
  20. 0.9Near Berkeley, California, United States10-05 05:03

Did you feel it?

Reports from people help show where shaking was strong. They are anonymous and shown here in aggregate.

Reports close 14 days after an earthquake.

Reports on SeismoAtlas

No reports yet.

USGS “Did You Feel It?” has 2 reports: add yours at USGS.

Event id nc75442482. First recorded here 28 Sept 2026, 17:32:09 UTC. Solutions: USGS · NC (usgs:nc75442482). Cite as: SeismoAtlas, “M2.3 earthquake 4 km WNW of Orinda, California, United States”, https://seismoatlas.com/earthquake/nc75442482-m2-3-earthquake-4-km-wnw-of-orinda-california-united-states, data from USGS.

JSON: /api/v1/events/nc75442482. SeismoAtlas is not an official warning service.