More than 230 aftershocks have hit parts of Alaska since on Friday when a massive 7.0-magnitude quake knocked out power, ripped open roads and damaged buildings near Anchorage, the US Geological Survey (USGS) said.
Most of the smaller earthquakes since Friday's big one were not felt. More than a dozen were higher than magnitude 4 and a handful greater than magnitude 5.
But a magnitude-5.2 aftershock at about 11 pm on Friday was the second-biggest event since a magnitude-5.7 temblor hit minutes after the main quake earlier in the day, a USGS official told CNN on Saturday.
"That would have given people a shake and probably a bit of a scare given what they went through yesterday.
The magnitude-7.0 earthquake sent residents scurrying for cover when it hit about 8.30 am on Friday. The quake was centred 10 miles northeast of Anchorage, the state's largest city with a population of about 300,000.
"This is the second largest earthquake we've had since 1964, which was a very significant earthquake," Anchorage Mayor Ethan Berkowitz told reporters on Saturday, referring a historic magnitude-9.2 quake that was the most powerful recorded temblor in US history.
"But in terms of a disaster, I think it says more about who we are than what we suffered. I would characterise this as a demonstration that Anchorage is prepared for these kind of emergencies."
Despite damage to roads and buildings, no fatalities or serious injuries were reported.
