Alaska 7.9 Magnitude Earthquake Shakes West Coast Ports

7.9 - 280km SE of Kodiak Alaska January 23 2018
7.9 - 280km SE of Kodiak Alaska January 23 2018

At 12:30 am on January 23, 2018,the United States Geological Survey (USGS) recorded a 7.9 magnitude earthquake struck off Alaska, at 56.046°N   149.073°W approximately 25.0 km in depth. The earthquake was originally recorded as 8.2 magnitude. The earthquake prompted a tsunami warning for a large area of the Alaska coast and Canada’s British Columbia, with watches for the rest of the U.S. West Coast and Hawaii. Officials at the National Tsunami Center canceled the warning after a few tense hours after waves failed to show up in coastal Alaska communities. No serious damage had been reported.

The January 23, 2018 M 7.9 earthquake southeast of Kodiak Island in the Gulf of Alaska occurred as the result of strike slip faulting within the shallow lithosphere of the Pacific plate. Focal mechanism solutions indicate faulting occurred on a steeply dipping fault striking either west-southwest (left lateral) or north-northwest (right lateral). At the location of the earthquake, the Pacific plate is converging with the North America plate at a rate of approximately 59 mm/yr towards the north-northwest. The Pacific plate subducts beneath the North America plate at the Alaska-Aleutians Trench, about 90 km to the northwest of today’s earthquake. The location and mechanism of the January 23rd earthquake are consistent with it occurring on a fault system within the Pacific plate before it subducts, rather than on the plate boundary between the Pacific and North America plates further to the northwest.

Nearby Places
Direction data (below) indicate the position of the event relative to the place.

  • Chiniak, Alaska 262.1 km (162.9 mi) SE Population: 47
  • Anchorage, Alaska 578.1 km (359.2 mi) S Population: 291,826
  • Eagle River, Alaska 588.3 km (365.5 mi) S Population: 24,793
  • Knik-Fairview, Alaska 609.6 km (378.8 mi) S Population: 14,923
  • Juneau, Alaska 919.1 km (571.1 mi) WSW Population: 31,275

Video: Magnitude 8.2 earthquake strikes Alaska, tsunami warning issued for US West Coast