M4.6 Earthquake 32 km S of Sand Point, Alaska — March 18, 2021
2021-03-18 22:50:25 UTC (2021-03-18) · approx. 11:50 AM UTC-11 local
On March 18, 2021 at 22:50 UTC, a magnitude 4.6 shallow crustal earthquake struck 32 km S of Sand Point, Alaska, at a depth of 49.6 km and coordinates 55.0458°, -160.4715°.
Physical scale: An earthquake of magnitude 4.6 releases seismic energy equivalent to roughly 120 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 899 m — a useful intuition for the size of the slip patch on the fault.
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
-160.4715°E
Technical Information
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Common Questions
How strong was the magnitude 4.6 earthquake near Sand Point, Alaska?
The magnitude 4.6 earthquake that struck 32 km S of Sand Point, Alaska on March 18, 2021 at 22:50 UTC had a depth of 49.6 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at 55.0458°, -160.4715°, which is 32 km S of Sand Point, Alaska. View all earthquakes in Alaska.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.6 earthquakes can continue for several days and gradually diminish over time.
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 4.6 event is significantly smaller than that historical record.
Authoritative source: USGS event page (event ID: us7000dks4). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, March 18, 2021). M4.6 Earthquake 32 km S of Sand Point, Alaska — March 18, 2021. Retrieved May 26, 2021 from https://www.earthquaketracker.org/earthquakes/event/us7000dks4/