M3.3 Earthquake 100 km SE of Atka, Alaska — July 23, 2026
2026-07-23 15:27:08 UTC (1 day ago) · approx. 3:27 AM UTC-12 local
On July 23, 2026 at 15:27 UTC, a magnitude 3.3 shallow crustal earthquake struck 100 km SE of Atka, Alaska, at a depth of 10.0 km and coordinates 51.5465°, -173.1903°.
Physical scale: An earthquake of magnitude 3.3 releases seismic energy equivalent to roughly 1.3 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 114 m — a useful intuition for the size of the slip patch on the fault.
This earthquake is part of an ongoing aftershock sequence following the magnitude 5.1 mainshock that occurred 2 days ago 92 km SE of Atka, Alaska. Since the mainshock, the USGS has recorded 8 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
Earthquake Details
-173.1903°E
Technical Information
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Common Questions
How strong was the magnitude 3.3 earthquake near Atka, Alaska?
The magnitude 3.3 earthquake that struck 100 km SE of Atka, Alaska on July 23, 2026 at 15:27 UTC had a depth of 10.0 km. For context, this was a minor earthquake typically detected only by instruments.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 3.3 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.1 one earlier?
No. This magnitude 3.3 earthquake is an aftershock of the larger magnitude 5.1 mainshock that occurred earlier 92 km SE of Atka, Alaska. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
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Understanding This Data
Magnitude 3.3 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: us7000t383). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2026, July 23, 2026). M3.3 Earthquake 100 km SE of Atka, Alaska — July 23, 2026. Retrieved July 25, 2026 from https://www.earthquaketracker.org/earthquakes/event/us7000t383/