The 2013 Magnitude 7.0 Earthquake Southwest of Atka, Alaska

On August 30, 2013, at 16:25 UTC, a magnitude 7.0 earthquake occurred 101 km southwest of Atka, Alaska, at a depth of 29 km. The event took place in the central Aleutian Islands, a region characterized by intense seismic activity driven by plate tectonics. Atka sits within the Aleutian volcanic arc, formed by the subduction of the Pacific Plate beneath the North American Plate at rates of approximately 6–7 cm per year. This convergent boundary generates frequent earthquakes, often at shallow to intermediate depths, as the descending slab interacts with the overriding plate. The 2013 earthquake aligns with this pattern, occurring within the subduction zone where megathrust and intraslab events are common. The Aleutian Islands have a long record of significant seismicity. Historical events include the 1957 M8.6 earthquake near the Andreanof Islands and the 1965 M8.7 Rat Islands earthquake, both of which produced widespread ground shaking and tsunamis. Modern monitoring by the Alaska Earthquake Center and USGS has documented ongoing activity, with the 2013 event representing one of the larger shocks in the central Aleutians during the early 21st century. The region's volcanoes, including Korovin and Kliuchef near Atka, also reflect the same tectonic forces, with eruptions often linked to stress changes from nearby earthquakes. Post-2013 data confirm continued seismic productivity in the area, consistent with the long-term behavior of the subduction zone. No major damage or casualties were reported from the 2013 mainshock, likely due to its offshore location and the sparse population of the central Aleutians.

References

USGS Earthquake Hazards Program event page for the 2013 Atka earthquake.
Alaska Earthquake Center regional seismicity reports.
USGS Tectonic Setting of the Aleutian Arc.