M3.1 Earthquake 81 km SE of Sand Point, Alaska — November 21, 2021
2021-11-21 16:20:45 UTC (2021-11-21) · approx. 5:20 AM UTC-11 local
On November 21, 2021 at 16:20 UTC, a magnitude 3.1 shallow crustal earthquake struck 81 km SE of Sand Point, Alaska, at a depth of 25.6 km and coordinates 54.8427°, -159.5533°.
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
-159.5533°E
Technical Information
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Common Questions
How strong was the magnitude 3.1 earthquake near Sand Point, Alaska?
The magnitude 3.1 earthquake that struck 81 km SE of Sand Point, Alaska on November 21, 2021 at 16:20 UTC had a depth of 25.6 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: us6000ge86). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, November 21, 2021). M3.1 Earthquake 81 km SE of Sand Point, Alaska — November 21, 2021. Retrieved January 29, 2022 from https://www.earthquaketracker.org/earthquakes/event/us6000ge86/