The 7.0 magnitude quake struck about 8 miles (13 km) north of Anchorage, a city of 300,000 residents accounting for about 40 percent of Alaska's population.
A powerful earthquake shook southern Alaska on November 30 morning, buckling roads, disrupting traffic and jamming telephone lines in and around Anchorage, the state's largest city, but there were no reports of injuries.
The 7.0 magnitude quake struck about 8 miles (13 km) north of Anchorage, a city of 300,000 residents accounting for about 40 percent of Alaska's population, and was followed by dozens of aftershocks.
Roads and bridges appeared to have been hardest hit, but Anchorage was otherwise largely spared from major structural damage, authorities said. Power outages and disruption of phone service were widespread.
"We did have a couple of reports of buildings collapses," Fire Chief Jodie Hettrick told reporters about three hours after the quake, adding that three structure fires also were reported, though details were not immediately available.
"The fact that we went through something this significant with this minimal amount of damage says that we're a very well prepared community, that our building codes and our building professionals have done a terrific job," Mayor Ethan Berkowitz said.
The initial quake produced strong shaking within a 30-mile (50 km) radius of its epicenter, with ground movement felt as far away as Fairbanks, 250 miles to the north as the crow flies, and Kodiak, roughly the same distance to the south, according to the U.S. Geological Survey (USGS).
"Thought the house was going to come apart," Anchorage-based climatologist Brian Brettschneider wrote on Twitter, posting a photo showing his kitchen floor scattered with items that tumbled out of cupboards.
A tsunami warning was issued for Cook Inlet, linking Anchorage with the Gulf of Alaska, but was later canceled.
The Trans Alaska Pipeline, which carries crude oil 800 miles (1,300 km) from Alaska's North Slope to the marine terminal at Valdez, was shut down for about seven hours as a precaution, but no damage to the system was detected, said a spokeswoman for the operator, Aleyska Pipeline Service Co.
The quake occurred nearly 27 miles (43 km) beneath the surface, apparently on an unnamed fault line, or fissure, inside a portion of the Earth's crust known as Pacific plate where it bends underneath the North American plate, USGS geophysicist Brian Kilgore told Reuters.
"This is kind of an odd quake," he said, adding that only 15 or 16 quakes of magnitude 6 or greater have been recorded during the past century in the same region of Alaska.
Morning rush-hour traffic in Anchorage came to a standstill and jammed up heading out of town after the quake struck at around 8:30 a.m. (1230 EST/1730 GMT).
Governor Bill Walker issued a disaster declaration, calling it a "scary day for Alaska."
"We have been through earthquakes in the past. This one was different. This was very, very scary, damage that we don‘t fully understand,â€ Walker said in a video statement from outside a National Guard armory command center.
President Donald Trump declared a federal emergency, ordering U.S. government assistance in the earthquake response and authorizing the Federal Emergency Management Agency to coordinate all disaster relief efforts, the White House said.
Strong earthquakes are not uncommon in seismically active Alaska but tend to occur in remote, sparsely populated regions.
Alaska has recorded earthquakes with magnitudes ranging from 7 to 8 at least once a year on average since 1900, according to the state government website. Southern Alaska was hit by a devastating 9.2 tremor in 1964, the second most powerful earthquake on record.
Images posted on social media showed supermarket floors strewn with spilled items.
A photo posted by a reporter at television station KTVA showed a deserted newsroom, with scattered debris and a partially collapsed ceiling. CNN reported that TV station KTUU, an NBC affiliate, also was knocked off the air.
KTUU's website featured a photo of a snow-covered highway that had buckled, with a car sitting between two deep fissures crossing the highway.
The Ted Stevens Anchorage International Airport remained open, but arrivals and departure ramps were closed and there were reports of road damage, the airport said on Twitter.The city's schools were evacuated and parents were notified to pick up their children.