M3.0 Earthquake 50 km ESE of Adak, Alaska — October 20, 2021
2021-10-20 17:10:38 UTC (2021-10-20) · approx. 5:10 AM UTC-12 local
On October 20, 2021 at 17:10 UTC, a magnitude 3.0 shallow crustal earthquake struck 50 km ESE of Adak, Alaska, at a depth of 3.1 km and coordinates 51.7289°, -175.9362°.
Physical scale: An earthquake of magnitude 3.0 releases seismic energy equivalent to roughly 477 kg of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 71 m — a useful intuition for the size of the slip patch on the fault.
Did You Feel It? — community-reported shaking
Aggregated felt-report intensity from 1 citizen response 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
-175.9362°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 3.0 earthquake near Adak, Alaska?
The magnitude 3.0 earthquake that struck 50 km ESE of Adak, Alaska on October 20, 2021 at 17:10 UTC had a depth of 3.1 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 3.0 earthquakes can continue for several days and gradually diminish over time.
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Understanding This Data
Magnitude 3.0 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: ak021dgunbfi). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, October 20, 2021). M3.0 Earthquake 50 km ESE of Adak, Alaska — October 20, 2021. Retrieved December 14, 2021 from https://www.earthquaketracker.org/earthquakes/event/ak021dgunbfi/