On October 4, 2024, a magnitude 1.6 earthquake occurred 37 miles east of Chenega Bay, Alaska. The earthquake’s depth was 12.1 miles (19 km), and it remains unreviewed by seismologists. Southern Alaska’s seismic activity is primarily driven by tectonic interactions between the Pacific and North American plates, with significant historical earthquakes shaping this region’s geological landscape.
On October 4, 2024, at 05:14:30 AKDT (13:14:30 UTC), a minor earthquake with a magnitude of 1.6 occurred approximately 37 miles east of Chenega Bay, Alaska, at a depth of 12.1 miles (19 kilometers). This seismic event has yet to be evaluated by a seismologist. The quake’s geographical location is notable, situated 46 miles south of Tatitlek, 47 miles southwest of Cordova, and 121 miles southeast of Anchorage, among other significant distances relative to nearby regions such as Middleton Island, Valdez, Whittier, and Thompson Pass. Southern Alaska’s geological framework is complex, characterized by numerous tectonic features that contribute to frequent seismic activity. Significant earthquakes in this region are primarily generated by the megathrust fault resulting from the interaction between the subducting Pacific Plate and the North American Plate. The Great Alaska Earthquake of 1964, with a magnitude of 9.2, remains a historical benchmark, being the second-largest earthquake on record globally. Intermediate-depth seismicity, occurring below 20 miles (32 kilometers), takes place within the Wadati-Benioff Zone, where the Pacific Plate descends beneath the North American Plate. This zone runs along key geographical features such as the Aleutian Arc and the Alaska Peninsula and ceases below the Alaska Range at a depth of approximately 140 miles (225 kilometers). Recent significant events in Southern Alaska include the M7.1 Iniskin earthquake of 2016 and the M7.1 Anchorage earthquake of 2018, both resulting in considerable ground shaking and structural damage across the Southcentral region. Moreover, crustal seismicity within Southern and Central Alaska is attributed to geological structures in areas such as the Cook Inlet basin and the Castle Mountain Fault. Noteworthy earthquakes linked to these structures include the 1933 M6.9 event, causing substantial damage in Anchorage, and the 1984 M5.6 Sutton earthquake, generated by the Castle Mountain Fault. The seismic zone extending between Cook Inlet and the Denali Fault shows complex interactions, which have been associated with numerous significant seismic events including the 1943 M7.0 earthquake, demonstrating the tectonic volatility of the area.
The seismic activity of Southern Alaska is influenced by a variety of tectonic interactions. The region’s earthquakes can be classified into three main categories: those arising from megathrust faults, intermediate-depth seismic events within the Wadati-Benioff Zone, and crustal seismicity related to local geological structures. These categories reflect the complexities of the geological makeup of the area, including the presence of subduction zones and active fault lines. As a result, Southern Alaska is prone to experiencing significant seismic events, making it a focal point for geological research and monitoring.
The earthquake recorded near Chenega Bay on October 4, 2024, serves as a reminder of the persistent seismic activity characteristic of Southern Alaska, underpinned by its complex tectonic setting. The historical context surrounding seismic events in this region underscores its vulnerability to both minor and major earthquakes, influenced by various geological factors such as megathrust faults and crustal seismicity associated with local geological phenomena. Continuous monitoring is essential for understanding and mitigating the impacts of such natural events.
Original Source: earthquake.alaska.edu
