A magnitude 8.2 earthquake struck 50 miles south of the Alaska Peninsula on July 28, 2021 at 10:15 pm local time (July 29, 2021 06:15 UTC). Seismic instruments indicate the earthquake originated at a depth of 20 miles (32.2 kilometers).
Perceived shaking for the quake was weak to light in Anchorage.
As of 2:51 am local time, 268 “Did You Feel It?” reports were submitted.
USGS scientists expect that this event will trigger aftershocks, but these will decrease in frequency over time. See the aftershock forecast for details.
The earthquake occurred as the result of thrust faulting at shallow depth on the subduction zone interface between the Pacific plate and the North America plate, where the Pacific plate begins subducting to the northwest beneath Alaska.
Large earthquakes in this region are common; the same subduction zone hosted the second largest earthquake recorded on modern instrumentation in March 1964 (M9.2 Alaska earthquake), and in 1938 a M8.2 event occurred in a very similar location to today’s earthquake.
The USGS is coordinating its response with the Alaskan Department of Natural Resources, Geological & Geophysical Surveys.
Visit the USGS earthquake event page for more information. For estimates of casualties and damage, visit the USGS Prompt Assessment of Global Earthquakes for Response (PAGER) website.
If you felt this earthquake, report your experience on the “USGS Did You Feel It?” website for this event.
For information about tsunami watches, warnings or advisories, visit the National Oceanic and Atmospheric Administration (NOAA) tsunami website.
The USGS operates a 24/7 National Earthquake Information Center in Colorado that can be reached for more information at 303-273-8500.
Learn more about the USGS Earthquake Hazards Program.