M3.2 Earthquake near Eastern Montana — July 21, 2023
2023-07-21 19:57:19 UTC (2023-07-21) · approx. 12:57 PM UTC-7 local
Felt by 34 people across nearby locations.
On July 21, 2023 at 19:57 UTC, a magnitude 3.2 shallow crustal earthquake struck near Eastern Montana, at a depth of 5.0 km and coordinates 45.5009°, -108.8538°. This earthquake was detected by 70 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 170, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 3.2 releases seismic energy equivalent to roughly 951 kg of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 97 m — a useful intuition for the size of the slip patch on the fault.
The epicenter is located in Montana, a region characterized by the Intermountain Seismic Belt, a diffuse zone of crustal deformation between the stable craton and the Basin and Range. View all earthquakes in Montana.
Learn more: Magnitude scale · Aftershock sequences
Did You Feel It? — community-reported shaking
Aggregated felt-report intensity from 34 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
-108.8538°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 3.2 earthquake near Eastern Montana?
The magnitude 3.2 earthquake that struck near Eastern Montana on July 21, 2023 at 19:57 UTC had a depth of 5.0 km. For context, this was a minor earthquake typically detected only by instruments.
Where did the earthquake occur?
The earthquake epicenter was located at 45.5009°, -108.8538°, which is near Eastern Montana. View all earthquakes in Montana.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 3.2 earthquakes can continue for several days and gradually diminish over time.
Has Montana had earthquakes this big before?
The largest recorded earthquake in Montana was the M7.3 Hebgen Lake earthquake of August 17, 1959. Today's magnitude 3.2 event is significantly smaller than that historical record.
Authoritative source: USGS event page (event ID: us7000khhb). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, July 21, 2023). M3.2 Earthquake near Eastern Montana — July 21, 2023. Retrieved September 28, 2023 from https://www.earthquaketracker.org/earthquakes/event/us7000khhb/