M3.1 Earthquake 144 km W of Adak, Alaska — May 23, 2021
2021-05-23 21:06:41 UTC (2021-05-23) · approx. 9:06 AM UTC-12 local
On May 23, 2021 at 21:06 UTC, a magnitude 3.1 intermediate depth earthquake struck 144 km W of Adak, Alaska, at a depth of 81.0 km and coordinates 51.6520°, -178.7003°.
Physical scale: An earthquake of magnitude 3.1 releases seismic energy equivalent to roughly 674 kg of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 83 m — a useful intuition for the size of the slip patch on the fault.
This earthquake is part of an ongoing aftershock sequence following the magnitude 5.3 mainshock that occurred 16 days ago 151 km WSW of Adak, Alaska. Since the mainshock, the USGS has recorded 27 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
Earthquake Details
-178.7003°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 3.1 earthquake near Adak, Alaska?
The magnitude 3.1 earthquake that struck 144 km W of Adak, Alaska on May 23, 2021 at 21:06 UTC had a depth of 81.0 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 3.1 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.3 one earlier?
No. This magnitude 3.1 earthquake is an aftershock of the larger magnitude 5.3 mainshock that occurred earlier 151 km WSW of Adak, Alaska. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
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Understanding This Data
Magnitude 3.1 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: us7000e5me). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, May 23, 2021). M3.1 Earthquake 144 km W of Adak, Alaska — May 23, 2021. Retrieved July 31, 2021 from https://www.earthquaketracker.org/earthquakes/event/us7000e5me/