Magnitude 3.5 - 111 miles S of Nikolski
July 31, 2020 10:43:57 AKDT (July 31, 2020 18:43:57 UTC)
51.3397°N 168.545°W Depth 18.6 miles (30 km)
This event has been reviewed by a seismologist
- 118 miles (191 km) SE of Herbert Island
- 119 miles (192 km) SE of Mt. Cleveland
- 123 miles (199 km) S of Mt. Vsevidof
- 124 miles (201 km) SE of Kagamil Island
- 125 miles (202 km) SE of Carlisle Island
- 125 miles (202 km) S of Mt. Recheshnoi
- 128 miles (207 km) SE of Yunaska Island
- 130 miles (210 km) SE of Uliaga Island
- 140 miles (226 km) SE of Chagulak Island
- 145 miles (235 km) S of Okmok Caldera
- 163 miles (264 km) SE of Amukta Pass
- 196 miles (317 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.