Largest landslide in New York State: 82 acres sliding in the Adirondacks

Photo by Lori Van Buren/Times Union
There is an excellent collection of photos in this article.

A record landslide started in New York state on May 6 in the hamlet of Keene Valley on Porter Mountain, a mountain pockmarked with scars of prehistoric landslides.  In a wonderful understatement about the power of gravity, associate state geologist and director of the state Geologic Mapping Program, Andrew Kozlowski said "We are talking about hundreds of thousands of tons and it is all moving, gravity has taken over."

Scarp at head of landslide

    















As of May 28, an 82 acre patch had slid 20 feet down the mountain, and was sliding a few inches a day. Spring melt from a heavy snowpack and heavy spring rains (9-12 inches in early May) had saturated the ground, triggering the slide. The ground on the mountain is composed of sand and glacial till.  It had been hoped that the spring blossoming of the trees would draw enough water out of the ground to slow or stop the slide. Unfortunately, that has not been the case. The movement stopped for a few days, but then picked up at an increasing rate and is now moving up to a foot a day. Residents are trying to move their homes, but insurance does not cover landslides in this area, the cost is ~$100,000, and time is running out.  One couple reports 15 feet of open air between their bedroom and the ground below (see article link in figure above).
     As of today, the TimesUnion reports that the scarp at the head of the landslide is eight tenths of a mile long and that the slide continues about a half-mile down the mountain. The vertical drop between the scarp and the toe is 300 feet. Kozlowski says that LIDAR (Light Detection And Ranging) mapping might have revealed landslide risks under the thick forest canopy, but has never been done.