Ridges of Arctic Ocean sea ice were shoved onto a Barrow road in quantities not seen in nearly three decades.
Two ice surges, known to Alaska Natives as ivus, stunned residents who had never seen large blocks of ice rammed ashore.
"It just looked like a big old mountain of ice," said L.A. Leavitt, 19, who left his nightshift job at the city early Tuesday to check out the ridges.
Ivus are like frozen tsunamis and crash ashore violently. They have killed hunters and are among the Arctic's most feared natural phenomena.
Residents said the northernmost ivu, about 20 feet high and 100 feet long, contained car-size blocks and left coastal Stevenson Road with only one lane.
The ice stopped about 30 feet short of a borough pump station that provides access to Barrow's underground water and sewer system, said North Slope Borough disaster coordinator Rob Elkins.
Strong winds from Russia and eastward currents began pushing pack ice toward Barrow on Saturday, Elkins said.
By late Monday night, thick, old sea ice, called multiyear ice, had shoved younger, thinner ice onto shore.
Elkins, who got a 5 a.m. Tuesday wake-up call from police, said a second ivu on the south side of town came to rest near a smaller coastal road and an empty playground. That ridge stretched about 200 feet.
"It was just an amazing sight," said Elkins, a five-year Barrow resident. "It looks like huge stacks of huge ice cubes."
The ivus, about two miles apart, had stopped moving when Elkins arrived. Bulldozers cleared the ice.
Winds from the west slowed Tuesday afternoon. Whalers also noted that a protective pressure ridge had formed more than a mile offshore.
Whaling captain Charlie Hopson, who coordinates oil spill responses in the area, said he could see blocks of ice churning slowly in the frozen ocean.
Whalers were happy to see the approach of multiyear ice. A solid platform of nearshore ice means safer travel and butchering.
"We always want this thing to happen before the whaling season to help get the ice solid and safe to travel on and then we can pick our way out to the lead," Hopson said.
Whaling co-captain Lloyd Leavitt said he had not seen such a big ivu since 1978, when winds peaked at 80 mph and blocks of multiyear ice about 12 feet thick slid ashore like pancakes from a frying pan.
"It knocked down all the power poles on the beach front, every last one from the Barrow mechanical building to Browerville," he said.