The landslide, located in Alaska's Inside Passage, is allegedly "one of the biggest ever seen in North America."
The slide began just below the ridge line of Lituya Mountain, in the Fairweather Mountain range, and descended through an unnamed valley before rolling over the back of Johns Hopkins Glacier. The stark contrast of black mud lying atop a crystalline landscape earned the slide a "chocolate frosting" comparison from Repanshek. The actual volume of the slide has not yet been assessed, but Repanshek notes "it registered as a relatively small, but noticeable earthquake. But it (the landslide) wasn't a result of an earthquake."
Research geomorphologist Dr. Marten Geertsema told Repanshek:
This thing is huge. Its 9 kilometers long, so 5.5 miles long. The (U.S. Geological Survey) recorded it at 3.4. Thats quite large for a seismic signal (from a landslide). ... If someone was trekking up this glacier when it happened, they would have been toast.
Geertsema added that it is not unusual to see a landslide like this, but it's the biggest North American slide he's ever seen.
To read more, and to see the landslide photography visit the National Parks Traveler report here.