Seismic Activity Overview: The October 2024 Tatitlek Earthquake and the Tectonic Setting of Southern Alaska

An earthquake measuring 1.5 in magnitude occurred near Tatitlek, Alaska, on October 16, 2024, with significant historical context regarding the region’s active tectonics. Southern Alaska’s seismic activity is primarily attributed to the subduction of the Pacific Plate beneath the North American Plate, with various geological features contributing to notable earthquake occurrences.

On October 16, 2024, an earthquake measuring 1.5 in magnitude occurred 45 miles northwest of Tatitlek, Alaska, at 05:05:39 AKDT (13:05:39 UTC). This seismic event registered a depth of 0.0 miles (0 km) and has yet to be reviewed by a seismologist. The quake’s geographical context places it significantly distanced from several key cities, including 45 miles west of Valdez, and 76 miles east of Anchorage. Southern Alaska’s seismic activity is attributed to a complex interplay of tectonic features. The most intense earthquakes occur along the megathrust fault where the Pacific Plate subducts beneath the North American Plate. Historically, notable earthquakes, such as the Great Alaska Earthquake of 1964, underscore this region’s seismic potential. Additionally, intermediate-depth seismicity occurs in the Wadati-Benioff Zone, a region beneath the North American Plate where the Pacific Plate descends into the mantle. Significant quakes, like the 2016 M7.1 Iniskin and the 2018 M7.1 Anchorage events, have highlighted the region’s vulnerability to substantial ground shaking and damage to infrastructure. Furthermore, crustal seismicity, which denotes earthquakes occurring closer to the surface, has its origins in several geological structures, including faults and folds in the Cook Inlet basin, the Castle Mountain Fault, and a vast diffuse seismic zone between the Cook Inlet and Denali Fault. Historical events, such as the April 1933 M6.9 earthquake and the 1984 M5.6 Sutton earthquake, reveal the damaging potential of these geological features.

The tectonic setting of southern Alaska is characterized by multiple active geological boundaries and fault lines that contribute to a high frequency of earthquakes. This seismic zone is primarily influenced by the interaction between the subducting Pacific Plate and the North American Plate, with significant historical seismic events steering research and public awareness of earthquake preparedness in the region. The area’s geological structures, including well-mapped faults and diffuse regions of seismic activity, have seen both minor and major earthquakes throughout history, demonstrating the need for ongoing seismological monitoring and study.

In conclusion, the recent earthquake near Tatitlek, although minor in magnitude, exemplifies the ongoing seismic threat faced by southern Alaska due to its complex tectonic setting. With several historical earthquakes resulting in significant damage, it is crucial to maintain vigilant monitoring and preparedness strategies in this seismically active region. Understanding the various causes of earthquakes here enhances awareness and preparedness for future potential seismic events.

Original Source: earthquake.alaska.edu