Southeast landslide may be one of North America's largest ever

AnchorageFebruary 25, 2014 

A massive landslide - so large that seismic networks recording earthquake activity detected its rumblings - has reshaped the contours of a mountain in Southeast Alaska.

Haines flightseeing pilot Drake Olson investigated the landslide, which he discovered about 62 nautical miles southwest of Haines on Mount La Perouse near the massive Brady Glacier in the Alaskan Panhandle.

It may be the largest natural landslide since the 2010 Bingham Canyon mine event, which was the largest North American landslide since humans have roamed the planet.

Durham University scientist David Petley reports on the La Perouse landslide and other significant slides around the earth for the American Geophysical Union's Landslide Blog.

Olson, who operates Fly Drake flightseeing and air service in Haines, flew over and took aerial images of the slide, which Petley estimates may have moved more than 20 million tons. Analyzing satellite imagery of the rock slide, Petley believes a vertical face of Mount La Perouse was sheered off, scattering mountainside and debris in an avalanche that extended nearly 5 miles.

The "crowning point" where the landslide originated came at about 9,186 feet up Mount La Perouse, with the avalanche toe at 3,477 feet, according to Petley's analysis.

Read more about the science behind seismologic analysis of landlslides around the world at the American Geophysical Union's Landslide Blog, where Petley and others offer several satellite and photographic images of the La Perouse slide.

EDITOR'S NOTE: This story originally, incorrectly identified Mount La Perouse as southeast of Haines. Mount La Perouse is southwest of Haines.

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