The magnitude 6.0 quake struck shortly before 1 a.m. and was centered in the ocean, about 200 miles south of the capital, Juneau, the U.S. Geological Survey said.
The Tsunami Warning Center said there was no danger of a tsunami.
The quake was widely felt across the region, but the Alaska Earthquake Information Center said it had no immediate reports of any damage.
The police dispatch office in the coastal town of Craig, 60 miles east of the epicenter, said the quake was felt but it had received no calls about damage or other problems.
Still, the USGS said the quake was strong enough to have an effect.
"There might be slight cracks in windows or walls or foundations, but not something where you would expect major devastation," said USGS geophysicist Amy Vaughan. "Certainly things might have been rattled off walls or off countertops or out of cabinets."
The center said the quake is an aftershock to a magnitude 7.5 temblor that struck on Jan. 4. That quake sparked a tsunami warning for hundreds of miles along the Alaska and Canadian coasts, but it was cancelled after a few hours when no damaging waves were generated.
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