M4.9 Earthquake 126 km E of McCarthy, Alaska — May 9, 2021
2021-05-09 02:03:46 UTC (2021-05-09) · approx. 5:03 PM UTC-9 local
On May 9, 2021 at 02:03 UTC, a magnitude 4.9 shallow crustal earthquake struck 126 km E of McCarthy, Alaska, at a depth of 5.1 km and coordinates 61.5060°, -140.5444°.
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.
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
-140.5444°E
Technical Information
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Common Questions
How strong was the magnitude 4.9 earthquake near McCarthy, Alaska?
The magnitude 4.9 earthquake that struck 126 km E of McCarthy, Alaska on May 9, 2021 at 02:03 UTC had a depth of 5.1 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at 61.5060°, -140.5444°, which is 126 km E of McCarthy, 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.
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: us7000e1gi). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, May 9, 2021). M4.9 Earthquake 126 km E of McCarthy, Alaska — May 9, 2021. Retrieved July 23, 2021 from https://www.earthquaketracker.org/earthquakes/event/us7000e1gi/