- Earthquakes
- Tsunamis
- Seismic Network
- About Us
Magnitude 3.9 - 49 miles SE of Herbert Island
February 3, 2023 17:33:08 AKST (February 4, 2023 02:33:08 UTC)
52.2202°N 169.3545°W Depth 13.3 miles (21 km)
This event has been reviewed by a seismologist
- 49 miles (79 km) SE of Mt. Cleveland
- 54 miles (87 km) S of Nikolski
- 55 miles (89 km) SE of Carlisle Island
- 55 miles (89 km) S of Kagamil Island
- 61 miles (98 km) S of Uliaga Island
- 63 miles (102 km) SE of Yunaska Island
- 68 miles (110 km) SW of Mt. Vsevidof
- 73 miles (118 km) SW of Mt. Recheshnoi
- 79 miles (128 km) E of Chagulak Island
- 98 miles (158 km) SW of Okmok Caldera
- 112 miles (181 km) E of Amukta Pass
- 165 miles (267 km) SW of Dutch
- 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.