M3.9 Earthquake 224 km WSW of Adak, Alaska — March 29, 2021
2021-03-29 23:20:36 UTC (2021-03-29) · approx. 11:20 AM UTC-12 local
On March 29, 2021 at 23:20 UTC, a magnitude 3.9 shallow crustal earthquake struck 224 km WSW of Adak, Alaska, at a depth of 51.0 km and coordinates 51.3459°, -179.7637°.
Physical scale: An earthquake of magnitude 3.9 releases seismic energy equivalent to roughly 11 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 296 m — a useful intuition for the size of the slip patch on the fault.
Earthquake Details
-179.7637°E
Technical Information
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Common Questions
How strong was the magnitude 3.9 earthquake near Adak, Alaska?
The magnitude 3.9 earthquake that struck 224 km WSW of Adak, Alaska on March 29, 2021 at 23:20 UTC had a depth of 51.0 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 3.9 earthquakes can continue for several days and gradually diminish over time.
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Understanding This Data
Magnitude 3.9 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: us6000dznn). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, March 29, 2021). M3.9 Earthquake 224 km WSW of Adak, Alaska — March 29, 2021. Retrieved June 8, 2021 from https://www.earthquaketracker.org/earthquakes/event/us6000dznn/