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May 27, 2017

USGS is collecting and analyzing air photos to help monitor a huge landslide that occurred May 20 on California’s Big Sur coast.

USGS is collecting and analyzing air photos to help monitor a huge landslide that occurred May 20 on California’s Big Sur coast. A quarter-mile-wide lobe of rock and soil has buried State Highway 1 and extends into the Pacific Oceanat Mud Creek, about 140 miles south of San Francisco. The USGS Pacific Coastal and Marine Science Center’s Remote Sensing Coastal Change project captured several photo sets during the recent slide activity and plans to shoot additional photos from airplane and drones during the coming weeks and months. Project scientists photograph the California coastline regularly and use “structure-from-motion” software to transform photos into 3D maps from which they can measure ground movement. They have flown and photographed the Big Sur coast several times this spring to track landslide activity in collaboration with geologists from the USGS Landslide Hazards Program. For additional information and images, please visit the Remote Sensing Coastal Change website.

A series of images takes a tour of the area of a large catastrophic landslide and shows the unstable slope before the event.
Imagery shows topographic point clouds created by the USGS from photos:September 11, 2015 courtesy of California Coastal Records Project,March 8, 2017 (USGS photo),May 19, 2017 (USGS photo), andMay 27, 2017 (USGS photo) 7 days following the catastrophic Highway 1 landslide.Last image shows the change in topography from the 2015 photo til the May 27, 2017 photo, with deeper red colors showing greater loss of elevation (up to 40 meters lost) and deeper purples showing a greater gain in elevation (up to 40 meters gained).Provisional Data Subject to Revision

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