There are no immediate reports of damage or injuries after Sunday morning's earthquake.
It was an aftershock of the magnitude 7.0 Anchorage earthquake that struck on Nov. 30.
The Alaska Earthquake Center says the moderate quake in the Cook Inlet area was located at a depth of about 21 miles (33 kilometers).
The center says people felt the quake throughout south-central Alaska.
According to the U.S. Geological Survey, people reported feeling weak-to-moderate shaking.