5.4 Magnitude Earthquake Hits 43 Miles Southwest of Seward
A magnitude 5.4 earthquake struck 43 miles southwest of Seward, Alaska, on October 30, 2025. The event occurred at 9:33 AM AKDT, at a depth of 14.6 miles (23 kilometers). Residents across the Kenai Peninsula and south-central Alaska reported feeling the tremor.
Seismic Details
The earthquake was detected at the following coordinates:
- Latitude: 59.6308°N
- Longitude: 150.2328°W
Seismologists confirmed the event’s details through regional data collected after the quake.
Impact on Local Areas
The tremor’s intensity prompted reports from several communities at significant distances from the epicenter. Key locations 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
- 62 miles (100 km) east of English Bay
- 110 miles (178 km) south of Anchorage
- 149 miles (241 km) northeast of Kodiak
Tectonic Setting of Alaska
Alaska’s earthquakes are primarily attributed to complex tectonic interactions. A significant tectonic feature is the megathrust fault, where the Pacific Plate subducts beneath the North American Plate. This zone is known for some of the region’s most powerful quakes, such as the 1964 M9.2 Great Alaska Earthquake.
Seismic Zones Overview
Seismic activity in Alaska is categorized into three primary zones:
- Megathrust Zone: The location of the Pacific Plate descent, resulting in the strongest earthquakes.
- Wadati-Benioff Zone: Hosts intermediate-depth seismicity, primarily affecting southern and central Alaska.
- Crustal Seismicity: Linked to various faults in the Cook Inlet basin and the Castle Mountain Fault.
Historical Context
Alaska has a history of significant seismic events. A notable quake in 1933 measured 6.9 and caused considerable damage in Anchorage, emphasizing the area’s seismic risk. The Castle Mountain Fault is also recognized for its ability to generate powerful earthquakes, including the 1984 M5.6 Sutton Earthquake. The recent 5.4 earthquake serves as a reminder of the dynamic geology in Alaska and the persistent seismic risks faced by its residents.
