M3.3 Earthquake 237 km ESE of Attu Station, Alaska — July 18, 2026
2026-07-18 20:02:12 UTC (2026-07-18) · approx. 8:02 AM UTC+12 local
On July 18, 2026 at 20:02 UTC, a magnitude 3.3 shallow crustal earthquake struck 237 km ESE of Attu Station, Alaska, at a depth of 10.0 km and coordinates 51.7958°, 176.2146°.
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 5.0 mainshock that occurred 17 days ago 236 km ESE of Attu Station, Alaska. Since the mainshock, the USGS has recorded 34 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
Earthquake Details
176.2146°E
Technical Information
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Common Questions
How strong was the magnitude 3.3 earthquake near Attu Station, Alaska?
The magnitude 3.3 earthquake that struck 237 km ESE of Attu Station, Alaska on July 18, 2026 at 20:02 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 M5.0 one earlier?
No. This magnitude 3.3 earthquake is an aftershock of the larger magnitude 5.0 mainshock that occurred earlier 236 km ESE of Attu Station, 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: us6000tmbs). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2026, July 18, 2026). M3.3 Earthquake 237 km ESE of Attu Station, Alaska — July 18, 2026. Retrieved September 17, 2026 from https://www.earthquaketracker.org/earthquakes/event/us6000tmbs/