5.4 Magnitude Earthquake Strikes 43 Miles Southwest of Seward
A 5.4 magnitude earthquake struck on October 30, 2025, at 09:33 AKDT, approximately 43 miles southwest of Seward, Alaska. The earthquake had a depth of 14.6 miles (23 km) and was felt throughout the Kenai Peninsula and south-central Alaska.
Details of the Earthquake
This seismic event occurred at the following coordinates: 59.6308°N latitude and 150.2328°W longitude. It has been reviewed by seismologists and its effects were noted in a wide area.
Impact Areas
- 46 miles (74 km) east of Homer
- 53 miles (85 km) east of Seldovia
- 56 miles (90 km) east of Anchor Point
- 57 miles (92 km) southeast of Clam Gulch
- 58 miles (94 km) southeast of Ninilchik
- 110 miles (178 km) south of Anchorage
- 149 miles (241 km) northeast of Kodiak
Tectonic Context of Southern Alaska
The earthquakes in the south-central region of Alaska result from various tectonic interactions. Key features include:
Subduction Zones
The most powerful earthquakes here occur along the megathrust fault, where the Pacific Plate subducts beneath the North American Plate. The notable 1964 M9.2 Great Alaska Earthquake, one of the strongest on record, originated in this area.
Intermediate-Depth Seismicity
Seismic activity occurring deeper than 20 miles (32 km) is observed in the Wadati-Benioff Zone. This area extends beneath the Alaska Range and has been responsible for several significant earthquakes, including the 2016 M7.1 Iniskin earthquake.
Crustal Seismicity
Local faults also contribute to seismic events. The Cook Inlet basin, Castle Mountain Fault, and surrounding geological structures are known to trigger powerful earthquakes. For example, a 1933 M6.9 earthquake caused considerable damage in Anchorage.
History of Significant Earthquakes
Historically, Alaska has experienced numerous significant earthquakes:
- 1964 Great Alaska Earthquake (M9.2)
- 2016 Iniskin Earthquake (M7.1)
- 2018 Anchorage Earthquake (M7.1)
- 1933 Anchorage Earthquake (M6.9)
- 1984 Sutton Earthquake (M5.6)
The ongoing seismic activity highlights the complex tectonic environment in this region. It remains essential for residents and local authorities to stay prepared for future events in Alaska.
