M5.6 Earthquake 57 km WNW of Skwentna, Alaska — August 8, 2026

On August 8, 2026 at 04:50 UTC, a magnitude 5.6 shallow crustal earthquake struck 57 km WNW of Skwentna, Alaska, at a depth of 10.0 km and coordinates 62.2690°, -152.3140°. The earthquake was reported felt by 1,068 peopleacross a wide area, with a maximum shaking intensity of Modified Mercalli Intensity (MMI) 5.9 (strong). This earthquake was detected by 228 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 1022, making it one of the most significant global earthquakes in recent days.

Physical scale: An earthquake of magnitude 5.6 releases seismic energy equivalent to roughly 4 kilotons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 4.4 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 6 aftershocks within 20 km of the epicenter, including 1 of magnitude 3.0 or greater. The strongest aftershock was a magnitude 3.2 event 1 hour ago. Aftershock sequences from mainshocks of magnitude 5.6 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