M4.5 Earthquake 139 km SE of Akutan, Alaska — August 1, 2023
2023-08-01 19:40:22 UTC (2023-08-01) · approx. 8:40 AM UTC-11 local
On August 1, 2023 at 19:40 UTC, a magnitude 4.5 shallow crustal earthquake struck 139 km SE of Akutan, Alaska, at a depth of 6.9 km and coordinates 53.3399°, -164.1378°. This earthquake was detected by 250 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 312, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 4.5 releases seismic energy equivalent to roughly 85 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 767 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
ShakeMap — predicted shaking intensity
Modeled ground-motion intensity contoured on the Modified Mercalli scale (MMI). Computed by the USGS from the moment-tensor solution and regional ground-motion prediction equations.
Source: U.S. Geological Survey ShakeMap. View interactive ShakeMap on USGS
Earthquake Details
-164.1378°E
Technical Information
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Common Questions
How strong was the magnitude 4.5 earthquake near Akutan, Alaska?
The magnitude 4.5 earthquake that struck 139 km SE of Akutan, Alaska on August 1, 2023 at 19:40 UTC had a depth of 6.9 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at 53.3399°, -164.1378°, which is 139 km SE of Akutan, Alaska. View all earthquakes in Alaska.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.5 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 4.5 event is significantly smaller than that historical record.
Authoritative source: USGS event page (event ID: us6000kx4m). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, August 1, 2023). M4.5 Earthquake 139 km SE of Akutan, Alaska — August 1, 2023. Retrieved October 7, 2023 from https://www.earthquaketracker.org/earthquakes/event/us6000kx4m/