This aerial photo shows damage on Vine Road, south of Wasilla, Alaska, after an earthquake Nov. 30. The quake shattered highways and rocked buildings in Anchorage and the surrounding area. (Marc Lester/Anchorage Daily News/AP)

Some of the most fascinating images to come out of the Alaska earthquake are the photos that show what geologists refer to as “slope failure,” in which portions of formerly solid hills caved in, tore or let loose and succumbed to gravity. And if there happened to be a road or other structure on top of the slope that failed, the result is dramatic.

Slopes can fail without earthquakes, as the result of torrential rain or weathering. But the shaking caused by a quake — particularly a large one like what occurred near Anchorage on Friday — can either speed up the process or create entirely new failures that wouldn’t have otherwise happened.

Several slope failures were documented in the Anchorage area in the hours after the earthquake Friday, the most interesting (and photogenic) of which was on Vine Road southwest of Wasilla. The photographer, Marc Lester, captured the image from a charter plane as he surveyed damage for the Anchorage Daily News.

“The roadway looked like pieces of a puzzle,” Lester wrote in a piece about how he got the photo. “The light snow cover helped the cracks in the Earth stand out and tell the story.”

It’s as if someone came along with a giant wrecking ball and dropped it on Vine Road, which crumpled like a smacked egg.

Geologists seemed surprised at how many slope failures occurred as a result of the 7.0-magnitude quake. The epicenter was deep, at 27 miles below the surface — a key reason the damage in Anchorage was relatively light. “Such an earthquake would be expected to generate shaking over a large area,” Dave Petley wrote on the American Geophysical Union blog, “but probably with reasonably modest peak ground accelerations.” Translation: Friday’s earthquake would certainly be felt, but the surface of Earth wouldn’t be moving dramatically enough to produce widespread landslides.

Photos from Alaska show a lot of lateral spread, in which the ground tears open, causing cracks and fissures. Whatever is on top of the ground at the place it tears in half is also subsequently torn in half, like highways or buildings. The buildings surrounding the perimeter of the spread are also at risk of damage because of the force of the ground spreading out away from the tear. There’s also documentation of block spreading, in which a portion of ground breaks off a hill and slides away mostly intact.


Damage from the Nov. 30 earthquake by Nancy Lake near Willow, Alaska. (Lloyd Tesch/Alaska Railroad Corp./AP)

Glenn Highway near Mirror Lake was hit hard by the earthquake. (Marc Lester/Anchorage Daily News/AP)

The southbound lanes of Glenn Highway between Eklutna and Mirror Lake were badly damaged. (Matt Tunseth/Anchorage Daily News/AP)

This image taken by the U.S. Air National Guard shows damage to a road in Alaska from the earthquake. (Air National Guard/AFP/Getty Images)

People walk along Vine Road in Wasilla after the Nov. 30 earthquake. (Jonathan M. Lettow/AP)

A ramp from International Airport Road to Minnesota Drive in Anchorage was damaged by the quake. (Marc Lester/Anchorage Daily News/AP)

Marty Thurman with Granite construction inspects a crack in the road at the International Airport Road off-ramp on southbound Minnesota Boulevard in Anchorage on Nov. 30. (Loren Holmes/Anchorage Daily News/AP)