M3.1 Earthquake 118 km SE of Perryville, Alaska — September 13, 2021
2021-09-13 17:23:49 UTC (2021-09-13) · approx. 6:23 AM UTC-11 local
On September 13, 2021 at 17:23 UTC, a magnitude 3.1 shallow crustal earthquake struck 118 km SE of Perryville, Alaska, at a depth of 5.3 km and coordinates 55.1581°, -157.8243°.
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.
Earthquake Details
-157.8243°E
Technical Information
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Common Questions
How strong was the magnitude 3.1 earthquake near Perryville, Alaska?
The magnitude 3.1 earthquake that struck 118 km SE of Perryville, Alaska on September 13, 2021 at 17:23 UTC had a depth of 5.3 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.
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Understanding This Data
Magnitude 3.1 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: ak021brnu8ym). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, September 13, 2021). M3.1 Earthquake 118 km SE of Perryville, Alaska — September 13, 2021. Retrieved November 23, 2021 from https://www.earthquaketracker.org/earthquakes/event/ak021brnu8ym/