M4.9 Earthquake 83 km SSE of Atka, Alaska — August 1, 2026
2026-08-01 23:07:03 UTC (35 min ago) · approx. 11:07 AM UTC-12 local
Aftershock of the M5.8 mainshock.
On August 1, 2026 at 23:07 UTC, a magnitude 4.9 shallow crustal earthquake struck 83 km SSE of Atka, Alaska, at a depth of 35.0 km and coordinates 51.5554°, -173.5639°. This earthquake was detected by 93 seismic stations with good location accuracy and was assigned a USGS significance rating of 369, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 4.9 releases seismic energy equivalent to roughly 338 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.4 km — 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 6 days ago 99 km SE of Atka, Alaska. Since the mainshock, the USGS has recorded 61 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
The epicenter is located in Alaska, a region characterized by Pacific Plate subduction beneath the North American Plate, producing frequent megathrust and crustal earthquakes along the Aleutian arc. The nearest mapped fault system is the Aleutian megathrust. View all earthquakes in Alaska.
Learn more: Magnitude scale · Aftershock sequences
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
-173.5639°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.9 earthquake near Atka, Alaska?
The magnitude 4.9 earthquake that struck 83 km SSE of Atka, Alaska on August 1, 2026 at 23:07 UTC had a depth of 35.0 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at 51.5554°, -173.5639°, which is 83 km SSE of Atka, Alaska. View all earthquakes in Alaska.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.9 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 4.9 earthquake is an aftershock of the larger magnitude 5.8 mainshock that occurred earlier 99 km SE of Atka, Alaska. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
Has Alaska had earthquakes this big before?
The largest recorded earthquake in Alaska was the M9.2 Great Alaska earthquake of March 27, 1964. Today's magnitude 4.9 event is significantly smaller than that historical record.
Authoritative source: USGS event page (event ID: us6000thii). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2026, August 1, 2026). M4.9 Earthquake 83 km SSE of Atka, Alaska — August 1, 2026. Retrieved August 1, 2026 from https://www.earthquaketracker.org/earthquakes/event/us6000thii/