M4.0 Earthquake 72 km SSW of Atka, Alaska — July 20, 2026
2026-07-20 14:37:50 UTC (12 hours ago) · approx. 2:37 AM UTC-12 local
On July 20, 2026 at 14:37 UTC, a magnitude 4.0 shallow crustal earthquake struck 72 km SSW of Atka, Alaska, at a depth of 19.8 km and coordinates 51.6020°, -174.6250°.
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
-174.6250°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.0 earthquake near Atka, Alaska?
The magnitude 4.0 earthquake that struck 72 km SSW of Atka, Alaska on July 20, 2026 at 14:37 UTC had a depth of 19.8 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.
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Understanding This Data
Magnitude 4.0 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: aka2026ognqvj). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2026, July 20, 2026). M4.0 Earthquake 72 km SSW of Atka, Alaska — July 20, 2026. Retrieved July 20, 2026 from https://www.earthquaketracker.org/earthquakes/event/aka2026ognqvj/