An 8.2 magnitude earthquake struck just off the coast of Alaska late Wednesday night, causing tremors that could be felt throughout the state and setting tsunami alarms blaring. The epicenter of the quake, the largest recorded in U.S. in more than 50 years, struck just over 50 miles offshore along the state’s Gulf of Alaska coast. After the shaking stopped, residents along the southwest peninsula moved to higher ground in anticipation of a possible tsunami.
A tsunami warning lasted nearly two hours—and a tsunami advisory was in place as far as Hawaii—but when waves hit the shoreline at about 7 inches above normal, the threat was downgraded and ultimately lifted several hours later. There were no reports of significant damage from the quake, though there were powerful aftershocks. The Alaska Earthquake Center recorded 14 aftershocks all magnitude 4 or higher in the two hours immediately after the initial shock, including two that registered at magnitudes of 6.2 and 5.6.
“The earthquake occurred as the result of thrust faulting at shallow depth on the subduction zone interface between the Pacific plate and the North America plate, where the Pacific plate begins subducting to the northwest beneath Alaska,” the U.S. Geological Survey writes. Alaska is a hotbed of seismic activity, registering as many as 49,000 events last year alone, but the latest quake is the third powerful earthquake to hit Alaska in the last 18 months. Alaska recorded the two most powerful quakes in the world in 2020.