M5.2 Earthquake 97 km SSW of Nikolski, Alaska — September 3, 2026

On September 3, 2026 at 11:24 UTC, a magnitude 5.2 shallow crustal earthquake struck 97 km SSW of Nikolski, Alaska, at a depth of 45.2 km and coordinates 52.1321°, -169.4182°. This earthquake was detected by 60 seismic stations with good location accuracy and was assigned a USGS significance rating of 416, placing it among routine seismic activity.

Physical scale: An earthquake of magnitude 5.2 releases seismic energy equivalent to roughly 951 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 2.3 km — a useful intuition for the size of the slip patch on the fault.

Active aftershock sequence: This earthquake is the mainshock of an ongoing aftershock sequence. In the 2 hours since the mainshock, the USGS has recorded 5 aftershocks within 20 km of the epicenter, including 5 of magnitude 3.0 or greater. The strongest aftershock was a magnitude 5.2 event 40 minutes ago. Aftershock sequences from mainshocks of magnitude 5.2 typically continue for days to weeks and gradually diminish over time, though occasional larger aftershocks remain possible.

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