M4.0 Earthquake 224 km ESE of Attu Station, Alaska — April 19, 2026
2026-04-19 21:49:17 UTC (2026-04-19) · approx. 9:49 AM UTC+12 local
On April 19, 2026 at 21:49 UTC, a magnitude 4.0 shallow crustal earthquake struck 224 km ESE of Attu Station, Alaska, at a depth of 10.0 km and coordinates 52.3790°, 176.4065°.
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.
This earthquake is part of an ongoing aftershock sequence following the magnitude 5.8 mainshock that occurred 11 days ago 235 km ESE of Attu Station, Alaska. Since the mainshock, the USGS has recorded 18 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
Earthquake Details
176.4065°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.0 earthquake near Attu Station, Alaska?
The magnitude 4.0 earthquake that struck 224 km ESE of Attu Station, Alaska on April 19, 2026 at 21:49 UTC had a depth of 10.0 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.
Is this the same earthquake as the M5.8 one earlier?
No. This magnitude 4.0 earthquake is an aftershock of the larger magnitude 5.8 mainshock that occurred earlier 235 km ESE of Attu Station, Alaska. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
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: us7000sgqp). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2026, April 19, 2026). M4.0 Earthquake 224 km ESE of Attu Station, Alaska — April 19, 2026. Retrieved May 18, 2026 from https://www.earthquaketracker.org/earthquakes/event/us7000sgqp/