M4.0 Earthquake 47 km ESE of Adak, Alaska — February 17, 2026
2026-02-17 23:17:00 UTC (2026-02-17) · approx. 11:17 AM UTC-12 local
On February 17, 2026 at 23:17 UTC, a magnitude 4.0 shallow crustal earthquake struck 47 km ESE of Adak, Alaska, at a depth of 59.6 km and coordinates 51.7835°, -175.9552°.
Physical scale: An earthquake of magnitude 4.0 releases seismic energy equivalent to roughly 15 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 347 m — a useful intuition for the size of the slip patch on the fault.
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
-175.9552°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.0 earthquake near Adak, Alaska?
The magnitude 4.0 earthquake that struck 47 km ESE of Adak, Alaska on February 17, 2026 at 23:17 UTC had a depth of 59.6 km. For context, this was a light earthquake commonly felt near the epicenter.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.0 earthquakes can continue for several days and gradually diminish over time.
What should I do after an earthquake?
If you were in the affected area: check yourself and others for injuries, inspect your home for damage, and be prepared for aftershocks. For detailed guidance, see our earthquake safety guide and emergency planning resources.
Actions
Understanding This Data
Magnitude 4.0 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us6000s9w6). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2026, February 17, 2026). M4.0 Earthquake 47 km ESE of Adak, Alaska — February 17, 2026. Retrieved May 14, 2026 from https://www.earthquaketracker.org/earthquakes/event/us6000s9w6/