M4.0 Earthquake 70 km SSW of Adak, Alaska — October 20, 2022
2022-10-20 23:40:10 UTC (2022-10-20) · approx. 11:40 AM UTC-12 local
On October 20, 2022 at 23:40 UTC, a magnitude 4.0 shallow crustal earthquake struck 70 km SSW of Adak, Alaska, at a depth of 35.0 km and coordinates 51.3239°, -177.1279°.
Physical scale: An earthquake of magnitude 4.0 releases seismic energy equivalent to roughly 15 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 347 m — a useful intuition for the size of the slip patch on the fault.
Earthquake Details
-177.1279°E
Technical Information
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Common Questions
How strong was the magnitude 4.0 earthquake near Adak, Alaska?
The magnitude 4.0 earthquake that struck 70 km SSW of Adak, Alaska on October 20, 2022 at 23:40 UTC had a depth of 35.0 km. For context, this was a light earthquake commonly felt near the epicenter.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.0 earthquakes can continue for several days and gradually diminish over time.
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Understanding This Data
Magnitude 4.0 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us7000indq). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2022, October 20, 2022). M4.0 Earthquake 70 km SSW of Adak, Alaska — October 20, 2022. Retrieved December 31, 2022 from https://www.earthquaketracker.org/earthquakes/event/us7000indq/