M3.1 Earthquake 9 km ENE of Blackhawk, CA — September 12, 2026
2026-09-12 07:25:55 UTC (2026-09-12) · approx. 11:25 PM UTC-8 local
Felt by 257 people across surrounding communities.
On September 12, 2026 at 07:25 UTC, a magnitude 3.1 shallow crustal earthquake struck 9 km ENE of Blackhawk, CA, at a depth of 15.9 km and coordinates 37.8628°, -121.8208°. This earthquake was detected by 193 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 237, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 3.1 releases seismic energy equivalent to roughly 722 kg of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 86 m — a useful intuition for the size of the slip patch on the fault.
The epicenter is located in California, a region characterized by the San Andreas transform fault system, where the Pacific and North American plates slide past each other at roughly 46 mm per year. The nearest mapped fault system is the San Andreas Fault. View all earthquakes in California.
Learn more: San Andreas Fault · Magnitude scale · Aftershock sequences
Did You Feel It? — community-reported shaking
Aggregated felt-report intensity from 257 citizen responses to the USGS Did You Feel It? system. Each colored zone represents the average MMI from reports in that area.
Source: U.S. Geological Survey Did You Feel It?. View on USGS · submit your own report
Earthquake Details
-121.8208°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 3.1 earthquake near Blackhawk, CA?
The magnitude 3.1 earthquake that struck 9 km ENE of Blackhawk, CA on September 12, 2026 at 07:25 UTC had a depth of 15.9 km. For context, this was a minor earthquake typically detected only by instruments.
Where did the earthquake occur?
The earthquake epicenter was located at 37.8628°, -121.8208°, which is 9 km ENE of Blackhawk, CA. View all earthquakes in California.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 3.1 earthquakes can continue for several days and gradually diminish over time.
Has California had earthquakes this big before?
The largest recorded earthquake in California was the M7.9 Fort Tejon earthquake of January 9, 1857. Today's magnitude 3.1 event is significantly smaller than that historical record.
Actions
Authoritative source: USGS event page (event ID: nc75434122). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2026, September 12, 2026). M3.1 Earthquake 9 km ENE of Blackhawk, CA — September 12, 2026. Retrieved October 6, 2026 from https://www.earthquaketracker.org/earthquakes/event/nc75434122/