M3.4 Earthquake 19km E of Ridgecrest, CA — September 24, 2021
2021-09-24 19:28:15 UTC (2021-09-24) · approx. 11:28 AM UTC-8 local
Felt by 11 people across nearby locations.
On September 24, 2021 at 19:28 UTC, a magnitude 3.4 shallow crustal earthquake struck 19km E of Ridgecrest, CA, at a depth of 3.8 km and coordinates 35.6053°, -117.4695°. The earthquake was reported felt by 11 peopleacross nearby locations, with a maximum shaking intensity of Modified Mercalli Intensity (MMI) 3.9 (light). This earthquake was detected by 48 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 186, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 3.4 releases seismic energy equivalent to roughly 2.2 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 142 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
ShakeMap — predicted shaking intensity
Modeled ground-motion intensity contoured on the Modified Mercalli scale (MMI). Computed by the USGS from the moment-tensor solution and regional ground-motion prediction equations.
Source: U.S. Geological Survey ShakeMap. View interactive ShakeMap on USGS
Did You Feel It? — community-reported shaking
Aggregated felt-report intensity from 11 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
-117.4695°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 3.4 earthquake near Ridgecrest, CA?
The magnitude 3.4 earthquake that struck 19km E of Ridgecrest, CA on September 24, 2021 at 19:28 UTC had a depth of 3.8 km. It was felt by 11 people with maximum shaking intensity of MMI 3.9 (light). For context, this was a minor earthquake typically detected only by instruments.
Where did the earthquake occur?
The earthquake epicenter was located at 35.6053°, -117.4695°, which is 19km E of Ridgecrest, CA. View all earthquakes in California.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 3.4 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 3.4 event is significantly smaller than that historical record.
Actions
Authoritative source: USGS event page (event ID: ci39818327). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, September 24, 2021). M3.4 Earthquake 19km E of Ridgecrest, CA — September 24, 2021. Retrieved December 4, 2021 from https://www.earthquaketracker.org/earthquakes/event/ci39818327/