On October 30, 2025, a magnitude 5.4 earthquake struck 43 miles southwest of Seward, Alaska. This seismic event occurred at 9:33 AM AKDT, with a depth of 14.6 miles (23 kilometers). It was notably felt across the Kenai Peninsula and throughout south-central Alaska.
Seismic Details
The earthquake was recorded at a location with coordinates 59.6308°N latitude and 150.2328°W longitude. Following the quake, seismologists confirmed the details based on regional seismic data.
Impact on Local Areas
The tremor’s intensity was significant enough to be felt in various communities. Notable distances from the epicenter include:
- 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
- 61 miles (98 km) southeast of Kasilof
Additional notable distances include: 62 miles (100 km) east of English Bay and 110 miles (178 km) south of Anchorage, along with 149 miles (241 km) northeast of Kodiak.
Tectonic Setting of Alaska
Earthquakes in Southcentral Alaska result from complex tectonic interactions. The major tectonic feature is the megathrust fault where the Pacific Plate subducts beneath the North American Plate. This zone is known for generating some of the region’s most powerful earthquakes, including the 1964 M9.2 Great Alaska Earthquake.
Seismic Zones Explained
Alaska’s seismic activity can be categorized into three main zones:
- Megathrust Zone: This is where the Pacific Plate descends, leading to the strongest earthquakes.
- Wadati-Benioff Zone: Intermediate-depth seismicity occurs here, affecting the southern and central parts of the state.
- Crustal Seismicity: This is linked to various faults within the Cook Inlet basin and the Castle Mountain Fault.
Historical Context
History shows that significant earthquakes have impacted this region. In 1933, a M6.9 quake caused notable damage in Anchorage, highlighting the local seismic risk. The Castle Mountain Fault has also shown capacity for generating strong quakes, evidenced by the 1984 M5.6 Sutton Earthquake.
This recent earthquake serves as a reminder of Alaska’s dynamic geology and the potential for seismic events. Residents and authorities remain alert to the ongoing risks associated with living in such a seismically active region.
