M3.8 Earthquake 56 km NE of Adak, Alaska — April 30, 2021
2021-04-30 15:15:34 UTC (2021-04-30) · approx. 3:15 AM UTC-12 local
On April 30, 2021 at 15:15 UTC, a magnitude 3.8 intermediate depth earthquake struck 56 km NE of Adak, Alaska, at a depth of 155.0 km and coordinates 52.2887°, -176.1486°.
Physical scale: An earthquake of magnitude 3.8 releases seismic energy equivalent to roughly 7.6 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 252 m — a useful intuition for the size of the slip patch on the fault.
Earthquake Details
-176.1486°E
Technical Information
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Common Questions
How strong was the magnitude 3.8 earthquake near Adak, Alaska?
The magnitude 3.8 earthquake that struck 56 km NE of Adak, Alaska on April 30, 2021 at 15:15 UTC had a depth of 155.0 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 3.8 earthquakes can continue for several days and gradually diminish over time.
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Understanding This Data
Magnitude 3.8 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: us7000dz16). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, April 30, 2021). M3.8 Earthquake 56 km NE of Adak, Alaska — April 30, 2021. Retrieved July 10, 2021 from https://www.earthquaketracker.org/earthquakes/event/us7000dz16/