Magnitude 3.0 - 131 miles S of Bobrof Island
May 20, 2023 21:22:26 AKDT (May 21, 2023 05:22:26 UTC)
50.0064°N 177.4024°W Depth 15.6 miles (25 km)
This event has been reviewed by a seismologist
- 133 miles (215 km) S of Adak
- 133 miles (215 km) S of Kanaga Volcano
- 134 miles (217 km) S of Tanaga Volcano
- 136 miles (220 km) S of Mt. Moffett
- 137 miles (222 km) SE of Mt. Gareloi
- 141 miles (228 km) S of Mt. Adagdak
- 152 miles (246 km) S of Great Sitkin Island
- 164 miles (265 km) SW of Atka Pass
- 170 miles (275 km) SW of Kasatochi Island
- 177 miles (286 km) SW of Mt. Sergief
- 182 miles (295 km) SW of Koniuji Island
- Magnitude type: Ml
- 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.