M3.1 Earthquake in the Unimak Island region, Alaska — September 20, 2023
2023-09-20 22:03:26 UTC (2023-09-20) · approx. 11:03 AM UTC-11 local
On September 20, 2023 at 22:03 UTC, a magnitude 3.1 shallow crustal earthquake struck in the Unimak Island region, Alaska, at a depth of 35.0 km and coordinates 53.6186°, -164.8151°.
Physical scale: An earthquake of magnitude 3.1 releases seismic energy equivalent to roughly 674 kg of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 83 m — a useful intuition for the size of the slip patch on the fault.
Earthquake Details
-164.8151°E
Technical Information
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Common Questions
How strong was the magnitude 3.1 earthquake in the Unimak Island region, Alaska?
The magnitude 3.1 earthquake that struck in the Unimak Island region, Alaska on September 20, 2023 at 22:03 UTC had a depth of 35.0 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 3.1 earthquakes can continue for several days and gradually diminish over time.
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Understanding This Data
Magnitude 3.1 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: us6000lclr). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, September 20, 2023). M3.1 Earthquake in the Unimak Island region, Alaska — September 20, 2023. Retrieved December 2, 2023 from https://www.earthquaketracker.org/earthquakes/event/us6000lclr/