M3.0 Earthquake 235 km W of Adak, Alaska — February 20, 2021
2021-02-20 17:31:09 UTC (2021-02-20) · approx. 5:31 AM UTC+12 local
On February 20, 2021 at 17:31 UTC, a magnitude 3.0 intermediate depth earthquake struck 235 km W of Adak, Alaska, at a depth of 171.8 km and coordinates 52.1966°, 179.9755°.
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.
Earthquake Details
179.9755°E
Technical Information
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Common Questions
How strong was the magnitude 3.0 earthquake near Adak, Alaska?
The magnitude 3.0 earthquake that struck 235 km W of Adak, Alaska on February 20, 2021 at 17:31 UTC had a depth of 171.8 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: us7000dgms). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, February 20, 2021). M3.0 Earthquake 235 km W of Adak, Alaska — February 20, 2021. Retrieved May 4, 2021 from https://www.earthquaketracker.org/earthquakes/event/us7000dgms/