© usgs.gov
The quake's epicenter hit near Cook Inlet, 162 miles southwest of Anchorage. It was about 50 miles deep.
Joshua Veldstra, a professional photographer who lives in Homer, said the earthquake lasted about 30 seconds.
"When it hit, it was just soft at first, and it just kept getting bigger," Veldstra said. "It was one of those moments where you didn't' know if it was going to get worse or if it was going to calm down."
Anchorage police tweeted that there were no reports of major damage or injury following the earthquake.
The USGS reported that there was a low likelihood of casualties and damage, but the agency's "Did You Feel It?" map [opposite] shows strong shaking could be felt near Anchorage.
The National Weather Service said there was no tsunami threat from the quake because of how deep it struck.
Two smaller earthquakes -- a 4.0 and a 3.2 -- struck within 30 minutes after the first one.
RT Ch2KTUU: A closer look at the #AKquake damage to K-Beach Road. Zach Moore & Myles Thomas photos. ... pic.twitter.com/bCSO4g77re
— Update: Earthquakes (@Earthquake_rt) January 24, 2016
Comment: This was a strong one, even for Alaska. There were about 30 aftershocks, with the strongest measuring about 4.3, and thousands of people have been left without power.
Videos from the event [warning: strong language]: