M3.9 Earthquake 159 km SSW of Adak, Alaska — December 9, 2020
2020-12-09 20:29:13 UTC (2020-12-09) · approx. 8:29 AM UTC-12 local
On December 9, 2020 at 20:29 UTC, a magnitude 3.9 shallow crustal earthquake struck 159 km SSW of Adak, Alaska, at a depth of 10.0 km and coordinates 50.5798°, -177.6248°.
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
-177.6248°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 159 km SSW of Adak, Alaska on December 9, 2020 at 20:29 UTC had a depth of 10.0 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: us7000cpkw). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2020, December 9, 2020). M3.9 Earthquake 159 km SSW of Adak, Alaska — December 9, 2020. Retrieved February 20, 2021 from https://www.earthquaketracker.org/earthquakes/event/us7000cpkw/