M3.9 Earthquake 71 km SE of Ugashik, Alaska — April 18, 2026
2026-04-18 18:53:08 UTC (2026-04-18) · approx. 8:53 AM UTC-10 local
On April 18, 2026 at 18:53 UTC, a magnitude 3.9 intermediate depth earthquake struck 71 km SE of Ugashik, Alaska, at a depth of 80.4 km and coordinates 57.0910°, -156.5100°.
Physical scale: An earthquake of magnitude 3.9 releases seismic energy equivalent to roughly 11 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 296 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
-156.5100°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 3.9 earthquake near Ugashik, Alaska?
The magnitude 3.9 earthquake that struck 71 km SE of Ugashik, Alaska on April 18, 2026 at 18:53 UTC had a depth of 80.4 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 3.9 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 3.9 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: aka2026hpwgqc). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2026, April 18, 2026). M3.9 Earthquake 71 km SE of Ugashik, Alaska — April 18, 2026. Retrieved July 3, 2026 from https://www.earthquaketracker.org/earthquakes/event/aka2026hpwgqc/