M2.5 Earthquake 4km SW of Humboldt Hill, CA — April 18, 2023
2023-04-18 21:27:56 UTC (2023-04-18) · approx. 1:27 PM UTC-8 local
On April 18, 2023 at 21:27 UTC, a magnitude 2.5 shallow crustal earthquake struck 4km SW of Humboldt Hill, CA, at a depth of 17.8 km and coordinates 40.7005°, -124.2178°.
Physical scale: An earthquake of magnitude 2.5 releases seismic energy equivalent to roughly 97.4 kg of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 34 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 4 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
-124.2178°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 2.5 earthquake near Humboldt Hill, CA?
The magnitude 2.5 earthquake that struck 4km SW of Humboldt Hill, CA on April 18, 2023 at 21:27 UTC had a depth of 17.8 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 2.5 earthquakes can continue for several days and gradually diminish over time.
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Understanding This Data
Magnitude 2.5 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: nc73875220). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, April 18, 2023). M2.5 Earthquake 4km SW of Humboldt Hill, CA — April 18, 2023. Retrieved July 3, 2023 from https://www.earthquaketracker.org/earthquakes/event/nc73875220/