M4.9 Earthquake 258 km SSE of False Pass, Alaska — November 4, 2020
2020-11-04 03:27:23 UTC (2020-11-04) · approx. 4:27 PM UTC-11 local
Aftershock of the M5.0 mainshock.
On November 4, 2020 at 03:27 UTC, a magnitude 4.9 shallow crustal earthquake struck 258 km SSE of False Pass, Alaska, at a depth of 11.8 km and coordinates 52.5802°, -162.5853°.
Physical scale: An earthquake of magnitude 4.9 releases seismic energy equivalent to roughly 338 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.4 km — 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 5.0 mainshock that occurred 15 days ago 244 km SSE of False Pass, Alaska. Since the mainshock, the USGS has recorded 0 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
The epicenter is located in Alaska, a region characterized by Pacific Plate subduction beneath the North American Plate, producing frequent megathrust and crustal earthquakes along the Aleutian arc. The nearest mapped fault system is the Aleutian megathrust. View all earthquakes in Alaska.
Learn more: Magnitude scale · Aftershock sequences
Earthquake Details
-162.5853°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.9 earthquake near False Pass, Alaska?
The magnitude 4.9 earthquake that struck 258 km SSE of False Pass, Alaska on November 4, 2020 at 03:27 UTC had a depth of 11.8 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at 52.5802°, -162.5853°, which is 258 km SSE of False Pass, Alaska. View all earthquakes in Alaska.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.9 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.0 one earlier?
No. This magnitude 4.9 earthquake is an aftershock of the larger magnitude 5.0 mainshock that occurred earlier 244 km SSE of False Pass, Alaska. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
Has Alaska had earthquakes this big before?
The largest recorded earthquake in Alaska was the M9.2 Great Alaska earthquake of March 27, 1964. Today's magnitude 4.9 event is significantly smaller than that historical record.
Authoritative source: USGS event page (event ID: us7000ca41). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2020, November 4, 2020). M4.9 Earthquake 258 km SSE of False Pass, Alaska — November 4, 2020. Retrieved December 22, 2025 from https://www.earthquaketracker.org/earthquakes/event/us7000ca41/