M3.4 Earthquake 157 km W of Nikolski, Alaska — September 18, 2020
2020-09-18 23:20:59 UTC (2020-09-18) · approx. 12:20 PM UTC-11 local
On September 18, 2020 at 23:20 UTC, a magnitude 3.4 intermediate depth earthquake struck 157 km W of Nikolski, Alaska, at a depth of 218.9 km and coordinates 52.8502°, -171.1992°.
Physical scale: An earthquake of magnitude 3.4 releases seismic energy equivalent to roughly 1.9 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 134 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 6.5 mainshock that occurred 20 days ago 177 km W of Nikolski, Alaska. Since the mainshock, the USGS has recorded 4 aftershocks in this area. Aftershock activity is expected to continue for weeks to months as stresses on surrounding faults redistribute.
Earthquake Details
-171.1992°E
Technical Information
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Common Questions
How strong was the magnitude 3.4 earthquake near Nikolski, Alaska?
The magnitude 3.4 earthquake that struck 157 km W of Nikolski, Alaska on September 18, 2020 at 23:20 UTC had a depth of 218.9 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 3.4 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M6.5 one earlier?
No. This magnitude 3.4 earthquake is an aftershock of the larger magnitude 6.5 mainshock that occurred earlier 177 km W of Nikolski, Alaska. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
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Understanding This Data
Magnitude 3.4 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: us6000c2pv). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2020, September 18, 2020). M3.4 Earthquake 157 km W of Nikolski, Alaska — September 18, 2020. Retrieved November 28, 2020 from https://www.earthquaketracker.org/earthquakes/event/us6000c2pv/