M2.4 Earthquake 4 km SE of San Ramon, CA — December 21, 2025
2025-12-21 22:36:09 UTC (2025-12-21) · approx. 2:36 PM UTC-8 local
On December 21, 2025 at 22:36 UTC, a magnitude 2.4 shallow crustal earthquake struck 4 km SE of San Ramon, CA, at a depth of 8.7 km and coordinates 37.7502°, -121.9455°.
Physical scale: An earthquake of magnitude 2.4 releases seismic energy equivalent to roughly 54.1 kg of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 26 m — a useful intuition for the size of the slip patch on the fault.
Did You Feel It? — community-reported shaking
Aggregated felt-report intensity from 1 citizen response 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
-121.9455°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 2.4 earthquake near San Ramon, CA?
The magnitude 2.4 earthquake that struck 4 km SE of San Ramon, CA on December 21, 2025 at 22:36 UTC had a depth of 8.7 km. For context, this was a minor earthquake typically detected only by instruments.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 2.4 earthquakes can continue for several days and gradually diminish over time.
What should I do after an earthquake?
If you were in the affected area: check yourself and others for injuries, inspect your home for damage, and be prepared for aftershocks. For detailed guidance, see our earthquake safety guide and emergency planning resources.
Actions
Understanding This Data
Magnitude 2.4 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: nc75284391). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2025, December 21, 2025). M2.4 Earthquake 4 km SE of San Ramon, CA — December 21, 2025. Retrieved May 23, 2026 from https://www.earthquaketracker.org/earthquakes/event/nc75284391/