Magnitude 5.4 - 56 miles SE of Douglas




August 10, 2025 05:26:43 AKDT (August 10, 2025 13:26:43 UTC)
57.8400°N 133.09°W    Depth 0.0 miles (0 km)

Measures of earthquake magnitude do not directly measure the size or impact of landslides. Depending on the methodology used, the magnitude computed for this event ranges from 3.1 to 5.4. The Alaska Earthquake Center typically uses a local magnitude (ML) calculation for events within Alaska. For this landslide, the ML is 3.1. The Global Centroid Moment Tensor Project calculated a moment magnitude (Mw) of 5.4. The National Earthquake Information Center calculated a surface wave magnitude (Ms) of 4.5. All of these magnitudes are different measures of the energy released during this event, calculated from different parts of the seismic waves with different algorithms.

This event has been reviewed by a seismologist

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Tectonic Setting of Southeast Alaska

Earthquakes in Southeast Alaska have shallow depths and are generally located along the Queen Charlotte and Fairweather faults, both of which are major transform plate boundaries. The Queen Charlotte Fault runs between the Pacific and North American plates, while the Fairweather Fault runs between the Yakutat microplate and North American Plate. The entire length of this fault system ruptured in major earthquakes over the past 90 years. The most significant event was a 1949 M8.1 earthquake that began in British Columbia and ruptured both south and north for a total of about 300 miles (483 km), crossing the border with Alaska. Other significant events in the region were the 1927 M7.1 event north of Sitka, and the 1958 M7.7 Lituya Bay, the 1972 M7.6 Sitka, and the 2013 M7.5 Craig earthquakes. The 2013 Craig Earthquake re-ruptured the northernmost part of the 1949 rupture zone.