USGS maps, measures huge landslide on California's Big Sur coast

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USGS scientists analyzing before-and-after air photos have calculated the size of the May 20 landslide on California’s Big Sur coast, about 140 miles south of San Francisco. 

Cutout view of Mud Creek landslide area
(Public domain.)

USGS scientists analyzing before-and-after air photos have calculated the size of the May 20 landslide on California’s Big Sur coast, about 140 miles south of San Francisco. They are sharing their information with California Department of Transportation (Caltrans) engineers assessing the slide. Preliminary calculations indicate that the landslide moved approximately 2 million cubic meters of material, enough to fill 800 Olympic-sized swimming pools. It buried State Highway 1 more than 20 meters (65 feet) deep and added more than 50,000 square meters (about 13 acres) of new land to the coast. USGS scientists shot air photos of the Big Sur coast in March and May 2017. Using “structure-from-motion” software, they transformed these and earlier photos into 3D maps that allow them to precisely measure areas and changes in ground elevation. They plan to keep monitoring the slide area via weekly airplane flights and, starting in June, drone flights.

Watch an animation of USGS computer-generated "before" and "after" images at Big Sur landslide. Red areas are lower, blue/purple higher. For additional information and images, please visit the USGS Remote Sensing Coastal Change website.