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Magnitude 3.5 - 48 miles S of Atka Pass
January 20, 2023 21:13:46 AKST (January 21, 2023 06:13:46 UTC)
51.3265°N 175.2264°W Depth 8.1 miles (13 km)
- 52 miles (84 km) S of Mt. Sergief
- 60 miles (97 km) S of Kasatochi Island
- 62 miles (100 km) S of Koniuji Island
- 63 miles (102 km) SE of Great Sitkin Island
- 72 miles (116 km) SE of Adak
- 74 miles (119 km) SW of Atka
- 74 miles (119 km) SE of Mt. Adagdak
- 77 miles (124 km) SE of Mt. Moffett
- 93 miles (150 km) SE of Kanaga Volcano
- 103 miles (167 km) E of Bobrof Island
- 131 miles (212 km) E of Tanaga Volcano
- Magnitude type: Ml2
- Event type: earthquake
Tectonic Setting of the Aleutian Islands
The world's largest earthquakes originate along convergent plate boundaries such as the Aleutian megathrust. Starting in 1938, a series of three great earthquakes ruptured the subduction zone along its entire length from the Alaska Peninsula to the western Aleutians with the exception of a small gap near the Shumagin Islands. The sequence began with a M8.2 earthquake southwest of Kodiak Island. A M8.6 in the Andreanof Islands followed in 1957, and the sequence concluded with the Rat Islands M8.7 in 1965. The Shumagin Gap still has not ruptured, but GPS observations suggest that little strain has built up in this region.
Another notable source of seismicity in the arc are the intermediate depth earthquakes within the subducting Pacific Plate, known as the Wadati-Benioff zone. The largest recorded earthquake of this kind was the 2014 M7.9 Little Sitkin event. Shallow earthquakes associated with volcano processes and crustal faults within the overriding North American plate occur regularly and may produce vigorous aftershock or swarm-like sequences.