Magnitude 3.2 - 50 miles SW of Seguam Island
November 20, 2020 18:16:38 AKST (November 21, 2020 03:16:38 UTC)
51.6729°N 172.9831°W Depth 17.5 miles (28 km)
This event has been reviewed by a seismologist
- 63 miles (102 km) SW of Amukta Pass
- 63 miles (102 km) SE of Atka
- 68 miles (110 km) SW of Amukta Pass
- 88 miles (142 km) E of Mt. Sergief
- 99 miles (160 km) E of Koniuji Island
- 100 miles (162 km) SW of Chagulak Island
- 105 miles (170 km) E of Atka Pass
- 113 miles (183 km) E of Kasatochi Island
- 117 miles (189 km) SW of Yunaska Island
- 136 miles (220 km) E of Great Sitkin Island
- 142 miles (230 km) SW of Herbert Island
- 310 miles (502 km) SW of Dutch
- Magnitude type: Ml2
- Event type: earthquake
Tectonic Setting of the Aleutian Islands
The Aleutian Arc marks the region where the Pacific Plate subducts into the mantle beneath the North American Plate. It is a seismically active region, evidenced by the thousands of earthquakes occurring each year. Since 1900, this region has hosted several major megathrust earthquakes, including the 1957 M8.6 in the Andreanof Islands, the 1965 M8.7 in the Rat Islands, the 1986 M7.9 and the 1996 M7.9 in the Andreanof Islands, and the 2003 M7.8 in the Rat Islands. Together they have ruptured the entire length of the megathrust boundary in this region. Another notable source of seismicity in the arc is the zone 6-9 miles (10-15 km) wide of intermediate-depth earthquakes within the subducting Pacific Plate, known as the Wadati-Benioff Zone. The largest recorded intermediate-depth earthquake in this region was the 2014 M7.9 Little Sitkin event. A third source of seismicity in this region are shallow earthquakes associated with volcanic processes and crustal faults within the overriding North American Plate. They occur regularly and may produce vigorous aftershock or swarm-like sequences.