The Alaska Peninsula is an area of significant seismic activity influenced by various tectonic features. One of the primary sources of powerful earthquakes in the region is the Aleutian megathrust. Recent notable seismic events include the 2020 M7.8 Simeonof Earthquake, which occurred near the Shumagin Islands, and the 2021 M8.2 Chignik Earthquake southwest of Kodiak Island. Fortunately, these recent significant quakes did not result in destructive tsunamis; however, historical records from Russian communities indicate previous tsunami events have occurred, and recently discovered paleo-tsunami deposits provide further evidence of these past occurrences.
Additionally, this region experiences intermediate-depth seismicity due to the activity in the Wadati-Benioff Zone, where the Pacific Plate is subducting under the North American Plate. This seismic zone stretches along the Aleutian Arc, Alaska Peninsula, and Cook Inlet, with seismic activity diminishing at depths of around 150 miles (241 km). Each year, thousands of earthquakes are recorded in the Aleutian-Alaska Wadati-Benioff Zone, the majority of which are of low magnitude and depth, making them imperceptible to the population. Among the most significant of these deeper events are the Kodiak Island earthquakes registered in 1999 (M7.0) and 2001 (M6.9), both of which caused notable disruption and damage.
Crustal seismicity is also present in the region, attributable to the Kodiak Shelf Fault Zone and the volcanic activity associated with the volcanic arc. An historic example of this was the series of M7+ earthquakes linked to the Novarupta eruption in 1912, which is recognized as the largest volcanic eruption of the 20th century worldwide.
Overall, the seismic landscape of the Alaska Peninsula is a testament to the dynamic tectonic processes at play, underscoring both the geological significance and the natural hazards faced by its inhabitants. The continuous monitoring of these seismic activities is crucial for public safety and preparedness in this seismically active region.