2023 Alaska Seismicity Summary

Natalia Ruppert et al.
Wed, 22 Apr 2026 17:17:36 PDT

The Alaska Earthquake Center reported 45,546 seismic events in Alaska and neighboring regions in 2023. The largest earthquake was a magnitude 7.2 event that occurred on July 16 in the Alaska Peninsula region. It was a late aftershock of the 2020 M7.8 Simeonof Earthquake. Other strong earthquakes include the October 16 M6.4 and December 21 M6.1 earthquakes in the Andreanof Islands region of the Aleutian Islands. The largest earthquake in mainland Alaska, magnitude 5.4, occurred in the lower Cook Inlet region on March 19. We continued to monitor ongoing activity within the 2018 M7.1 Anchorage, 2018 M6.4 Kaktovik, 2018 M7.9 Offshore Kodiak, 2020 M7.8 Simeonof, and 2021 M8.2 Chignik aftershock sequences, the Purcell Mountains earthquake swarm, and the Wright Glacier cluster northeast of Juneau. All aftershock sequences continued to slow down compared to the previous years.