M3.3 Earthquake 9 km SSE of Colstrip, Montana — December 29, 2021
2021-12-29 20:21:20 UTC (2021-12-29) · approx. 1:21 PM UTC-7 local
On December 29, 2021 at 20:21 UTC, a magnitude 3.3 shallow crustal earthquake struck 9 km SSE of Colstrip, Montana, at a depth of 0.0 km and coordinates 45.7967°, -106.5974°.
Physical scale: An earthquake of magnitude 3.3 releases seismic energy equivalent to roughly 1.3 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 114 m — a useful intuition for the size of the slip patch on the fault.
Earthquake Details
-106.5974°E
Technical Information
Common Questions
How strong was the magnitude 3.3 earthquake near Colstrip, Montana?
The magnitude 3.3 earthquake that struck 9 km SSE of Colstrip, Montana on December 29, 2021 at 20:21 UTC had a depth of 0.0 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 3.3 earthquakes can continue for several days and gradually diminish over time.
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Understanding This Data
Magnitude 3.3 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: us7000g7s1). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, December 29, 2021). M3.3 Earthquake 9 km SSE of Colstrip, Montana — December 29, 2021. Retrieved March 5, 2022 from https://www.earthquaketracker.org/earthquakes/event/us7000g7s1/