M3.9 Earthquake 173 km S of Nikolski, Alaska — July 31, 2020
2020-07-31 19:47:58 UTC (2020-07-31) · approx. 8:47 AM UTC-11 local
On July 31, 2020 at 19:47 UTC, a magnitude 3.9 shallow crustal earthquake struck 173 km S of Nikolski, Alaska, at a depth of 10.0 km and coordinates 51.3854°, -168.6171°.
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
-168.6171°E
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Common Questions
How strong was the magnitude 3.9 earthquake near Nikolski, Alaska?
The magnitude 3.9 earthquake that struck 173 km S of Nikolski, Alaska on July 31, 2020 at 19:47 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: us6000b7ls). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2020, July 31, 2020). M3.9 Earthquake 173 km S of Nikolski, Alaska — July 31, 2020. Retrieved October 10, 2020 from https://www.earthquaketracker.org/earthquakes/event/us6000b7ls/