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M1.6 earthquake 10 km ENE of Blackhawk, California, United States

A magnitude 1.6 earthquake struck 10 km ENE of Blackhawk, California, United States at 11:18 local time (18:18 UTC) on 21 Oct 2026, at a depth of 7 km, according to USGS. The solution is preliminary and may be revised.

Data: USGS · updated 2026-10-21 18:19 UTC · automatic solution

Magnitude
1.6micro
duration magnitude (md)
Depth
6.7 km
Status
Automatic
Origin time
2026-10-21 18:18:00 UTC
Local: 21 Oct 2026, 11:18:00 (America/Los Angeles)
Epicentre
37.843° N, 121.797° 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
BlackhawkCalifornia, United States · pop. 9,35410 kmINot felt
BrentwoodCalifornia, United States · pop. 58,96813 kmINot felt
San RamonCalifornia, United States · pop. 76,13417 kmINot felt
AntiochCalifornia, United States · pop. 110,54218 kmINot felt
DanvilleCalifornia, United States · pop. 44,40018 kmINot felt
OaklandCalifornia, United States · pop. 419,26742 kmINot felt
StocktonCalifornia, United States · pop. 305,65846 kmINot felt
San FranciscoCalifornia, United States · pop. 827,52655 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.

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 Survey1.6 md6.7 km37.84° N, 121.80° W–Automatic

How big was it?

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

It released roughly the energy of 4 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 7 km this was a shallow earthquake, which is felt more strongly at the surface than a deeper one of the same size.

M1.6 releases about 7.4× the energy of M1.0, and its waves are about 3.8× taller on a seismogram. Energy: 4 kg of TNT vs 477 g of TNT.

Each square is the energy of one M1.0. Energy from log₁₀E = 1.5M + 4.8.

Aftershocks and nearby activity

19 later earthquakes within 30 km; the largest was M2.5 10 days ago. 10 in the 7 days before. Aftershock rates usually fall off roughly in proportion to 1/time.

Aftershocks

Mainshock M1.6

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

Aftershocks
Time after mainshock (hours)MagnitudeDepth (km)
106.481.315
135.141.110
141.572.11
211.651.41
232.201.615
232.961.415
233.231.615
236.012.115
236.041.317
236.721.310
257.012.116
279.092.513
288.241.910
304.411.27
337.791.89
387.511.20
425.802.111
474.961.110
521.521.20
  1. 2.5Near Pleasant Hill, California, United States11-02 09:23
  2. 2.14 km ENE of Danville, California, United States10-31 14:18
  3. 2.1Near Pleasant Hill, California, United States11-08 12:05
  4. 2.1Near Concord, California, United States11-01 11:18
  5. 2.112 km SE of Livermore, California, United States10-27 15:52
  6. 1.94 km SW of Dublin, California, United States11-02 18:32
  7. 1.8Near Pleasant Hill, California, United States11-04 20:05
  8. 1.64 km ENE of Danville, California, United States10-31 10:30
  9. 1.64 km ENE of Danville, California, United States10-31 11:31
  10. 1.44 km ENE of Danville, California, United States10-31 11:15
  11. 1.412 km SE of Livermore, California, United States10-30 13:57
  12. 1.35 km SSW of Pittsburg, California, United States10-26 04:46
  13. 1.34 km WNW of Blackhawk, California, United States10-31 14:20
  14. 1.34 km W of Blackhawk, California, United States10-31 15:01
  15. 1.2Near Clayton, California, United States11-06 21:48
  16. 1.2Near Danville, California, United States11-03 10:42
  17. 1.212 km SE of Livermore, California, United States11-12 11:49
  18. 1.1Near Alamo, California, United States10-27 09:26
  19. 1.1Near Pleasant Hill, California, United States11-10 13:15

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.

Event id nc75452966. First recorded here 21 Oct 2026, 18:20:58 UTC. Solutions: USGS · NC (usgs:nc75452966). Cite as: SeismoAtlas, “M1.6 earthquake 10 km ENE of Blackhawk, California, United States”, https://seismoatlas.com/earthquake/nc75452966-m1-6-earthquake-10-km-ene-of-blackhawk-california-united-states, data from USGS.

JSON: /api/v1/events/nc75452966. SeismoAtlas is not an official warning service.