Friday, 14 Dec 2018

Alaska earthquake: incredible images of where the ground is torn in two

This aerial photo shows the damage on Vine Road, south of Wasilla, Alaska after the November 30th earthquake. The earthquake destroyed highways and tipped buildings in and around Anchorage. (Marc Lester / Anchorage Daily News / AP) Some of the most fascinating images from the Alaska earthquake are the photos showing what geologists call a "slope failure," in which portions of hills left loose and succumbed to gravity. And if there was a road or other structure at the top of the slope that failed, the result is dramatic. The slopes can collapse without an earthquake, as a result of a torrential rain or inclement weather. But the tremor caused by an earthquake – especially a major earthquake near Anchorage on Friday – may either speed up the process or create new failures that would otherwise not have happened. Several slope failures have been documented in the Anchorage area in the hours that followed Friday's earthquake, the most interesting (and photogenic) of which was on Vine Road, southwest of Wasilla. The photographer, Marc Lester, captured the image of a charter plane while he was investigating the damage suffered by Anchorage Daily News. "The pavement looked like a puzzle," Lester wrote in an article about how he got the photo. "The light snow layer has allowed the Earth's cracks to stand out and tell the story." Geologists seemed surprised by the number of slope failures that followed the magnitude 7.0 earthquake. The epicenter was deep, 27 miles below the surface – a major reason why damage to Anchorage was relatively light. "Such an earthquake should generate jolts over a large area," Dave Petley wrote on the American Geophysical Union's blog, "but probably with reasonably modest peak accelerations." The photos of Alaska show a large lateral dispersion in which the soil opens and causes cracks. Everything that is on the ground where it is torn in two is also later, like a highway or a building. Buildings surrounding the perimeter of the spread may also be damaged due to the strength of the soil that spreads far from the tear. There are also documents on the spreading of blocks, in which part of the ground breaks a hill and slips largely intact.
Damage caused by the November 30 earthquake at Lake Nancy, near Willow, Alaska. (Lloyd Tesch / Alaska Railroad Corp. / AP)

Glenn Road near Mirror Lake was severely affected by the earthquake. (Marc Lester / Anchorage Daily News / AP)

The southbound lanes of the Glenn Road between Eklutna and Mirror Lake have been seriously damaged. (Matt Tunseth / Anchorage Daily News / AP)

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

People walk along the vineyard road in Wasilla after the November 30 earthquake. (Jonathan M. Lettow / AP)

An access ramp connecting International Airport Road to Minnesota Drive in Anchorage was damaged by the earthquake. (Marc Lester / Anchorage Daily News / AP)

Marty Thurman, of Granite, inspects a crack in the road at the International Airport Road off-ramp on Minnesota Boulevard heading south to Anchorage on November 30th.

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