ATKA, ALASKA / RankWire.AI / – A magnitude 5.0 earthquake struck southeast of Atka in Alaska’s Aleutian Islands late Saturday. The Alaska Earthquake Center recorded the event at 7:36 p.m. Alaska Daylight Time on August 8. That time corresponded to 03:36 UTC on August 9. The quake originated about 48 miles, or 77 kilometers, southeast of Atka. Seismologists calculated a depth of roughly 10.6 miles, or 17 kilometers.
The reviewed earthquake occurred at 51.8286 degrees north latitude and 173.2496 degrees west longitude. Scientists measured the event at magnitude 5.0 using the local magnitude scale. Atka lies on Atka Island in the central Aleutian chain. The remote community sits hundreds of miles from Alaska’s largest population centers. Earthquakes occur frequently across this region because several active geological structures extend beneath the North Pacific.
The epicenter also fell southwest of Seguam Island and Amukta Pass. Mount Sergief lies west of the recorded earthquake location. Other islands and volcanic features surround the wider seismic zone. The event occurred at a relatively shallow depth for an Aleutian earthquake. The region also produces much deeper earthquakes within the descending Pacific Plate. Seismologists use location, depth and magnitude measurements to distinguish these different types of seismic activity.
Aleutian chain experiences frequent earthquakes
The Aleutian Arc forms one of the most active earthquake regions in Alaska. The Pacific Plate moves beneath the North American Plate along this extensive boundary. Scientists call this geological process subduction. It generates earthquakes across a broad range of depths and magnitudes. The same tectonic setting extends for thousands of kilometers through the North Pacific. Alaska records thousands of earthquakes each year, with many occurring beneath or near the Aleutian Islands.
The Aleutian region has also produced several of the strongest earthquakes recorded in Alaska. A magnitude 8.6 earthquake struck the Andreanof Islands in 1957. The Rat Islands experienced a magnitude 8.7 earthquake in 1965. Large earthquakes also struck the Andreanof Islands in 1986 and 1996. These events occurred along the same broad plate boundary that drives much of Alaska’s seismic activity. Their locations and depths varied across the Aleutian system.
Seismic networks track activity statewide
Earthquakes around the Aleutians can develop in several parts of the regional tectonic system. Some occur along the main boundary between the Pacific and North American plates. Others form deeper inside the Pacific Plate as it descends beneath Alaska. Shallow crustal earthquakes can also occur within the overriding plate. The U.S. Geological Survey maintains national earthquake records and publishes reviewed measurements for seismic events across Alaska and the wider United States.
The August 8 earthquake adds another magnitude 5.0 event to Alaska’s extensive seismic record. Its location southeast of Atka places it within a well-known zone of regular earthquake activity. The measured depth of 17 kilometers identifies it as a shallow event by regional standards. Monitoring stations across Alaska detect ground motion from remote islands and mainland communities. Scientists then review those signals to refine earthquake locations, magnitudes and depths across the state.