M1.3 earthquake 4 km W of Blackhawk, California, United States
A magnitude 1.3 earthquake struck 4 km W of Blackhawk, California, United States at 08:01 local time (15:01 UTC) on 31 Oct 2026, at a depth of 10 km, according to USGS. The solution is preliminary and may be revised.
Data: USGS · updated 2026-10-31 15:02 UTC · automatic solution
- Magnitude
- 1.3micro
duration magnitude (md) - Depth
- 10.5 km
- Status
- Automatic
- Origin time
- 2026-10-31 15:01:12 UTC
- Local: 31 Oct 2026, 08:01:12 (America/Los Angeles)
- Epicentre
- 37.819° N, 121.950° 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
| Place | Distance | Est. shaking |
|---|---|---|
| BlackhawkCalifornia, United States · pop. 9,354 | 4 km | INot felt |
| DanvilleCalifornia, United States · pop. 44,400 | 4 km | INot felt |
| San RamonCalifornia, United States · pop. 76,134 | 5 km | INot felt |
| DublinCalifornia, United States · pop. 57,721 | 13 km | INot felt |
| Walnut CreekCalifornia, United States · pop. 68,910 | 14 km | INot felt |
| OaklandCalifornia, United States · pop. 419,267 | 28 km | INot felt |
| San FranciscoCalifornia, United States · pop. 827,526 | 42 km | INot felt |
| San JoseCalifornia, United States · pop. 997,368 | 54 km | INot 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.
| Agency | Magnitude | Depth | Epicentre | Time offset | Status |
|---|---|---|---|---|---|
| USGS · NCheadlineNorthern California Seismic System via U.S. Geological Survey | 1.3 md | 10.5 km | 37.82° N, 121.95° W | – | Automatic |
How big was it?
Usually not felt. Recorded by nearby seismometers; thousands occur worldwide every day.
It released roughly the energy of 1 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 10 km this was a shallow earthquake, which is felt more strongly at the surface than a deeper one of the same size.
M1.3 releases about 2.5× the energy of M1.0, and its waves are about 1.8× taller on a seismogram. Energy: 1 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
11 later earthquakes within 30 km; the largest was M2.6 10 days ago. 8 in the 7 days before. Aftershock rates usually fall off roughly in proportion to 1/time.
Mainshock M1.3
11 later earthquakes nearby. Aftershock rates typically fall off roughly as 1/time (Omori's law).
| Time after mainshock (hours) | Magnitude | Depth (km) |
|---|---|---|
| 20.29 | 2.1 | 16 |
| 35.37 | 2.6 | 10 |
| 35.50 | 1.6 | 10 |
| 42.37 | 2.5 | 13 |
| 51.52 | 1.9 | 10 |
| 67.69 | 1.2 | 7 |
| 101.07 | 1.8 | 9 |
| 150.79 | 1.2 | 0 |
| 189.08 | 2.1 | 11 |
| 238.24 | 1.1 | 10 |
| 268.78 | 1.4 | 10 |
- 2.6Near Berkeley, California, United States11-02 02:23
- 2.5Near Pleasant Hill, California, United States11-02 09:23
- 2.1Near Pleasant Hill, California, United States11-08 12:05
- 2.1Near Concord, California, United States11-01 11:18
- 1.94 km SW of Dublin, California, United States11-02 18:32
- 1.8Near Pleasant Hill, California, United States11-04 20:05
- 1.6Near Berkeley, California, United States11-02 02:31
- 1.4Near Berkeley, California, United States11-11 19:48
- 1.2Near Clayton, California, United States11-06 21:48
- 1.2Near Danville, California, United States11-03 10:42
- 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 on SeismoAtlas
No reports yet.
Event id nc75460317. First recorded here 31 Oct 2026, 15:03:05 UTC. Solutions: USGS · NC (usgs:nc75460317). Cite as: SeismoAtlas, “M1.3 earthquake 4 km W of Blackhawk, California, United States”, https://seismoatlas.com/earthquake/nc75460317-m1-3-earthquake-4-km-w-of-blackhawk-california-united-states, data from USGS.
JSON: /api/v1/events/nc75460317. SeismoAtlas is not an official warning service.