M5.5 Earthquake 46 km NNW of Attu Station, Alaska — April 2, 2025
2025-04-02 16:26:35 UTC (2025-04-02) · approx. 4:26 AM UTC+12 local
Maximum shaking intensity MMI 4.6 (moderate).
On April 2, 2025 at 16:26 UTC, a magnitude 5.5 shallow crustal earthquake struck 46 km NNW of Attu Station, Alaska, at a depth of 14.0 km and coordinates 53.2407°, 172.9610°. The USGS PAGER system issued a green alert level for this event, indicating no significant casualties or damage expected. This earthquake was detected by 278 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 465, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 5.5 releases seismic energy equivalent to roughly 3 kilotons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 3.8 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
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
172.9610°E
Technical Information
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Common Questions
How strong was the magnitude 5.5 earthquake near Attu Station, Alaska?
The magnitude 5.5 earthquake that struck 46 km NNW of Attu Station, Alaska on April 2, 2025 at 16:26 UTC had a depth of 14.0 km. For context, this was a moderate earthquake that could be widely felt.
Where did the earthquake occur?
The earthquake epicenter was located at 53.2407°, 172.9610°, which is 46 km NNW of Attu Station, Alaska. View all earthquakes in Alaska.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 5.5 earthquakes can continue for days to weeks 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 5.5 event is significantly smaller than that historical record.
Authoritative source: USGS event page (event ID: us7000ppga). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2025, April 2, 2025). M5.5 Earthquake 46 km NNW of Attu Station, Alaska — April 2, 2025. Retrieved June 9, 2025 from https://www.earthquaketracker.org/earthquakes/event/us7000ppga/