Mount La Perouse ‘‹a 10,728-foot peak in the Fairweather Range in Glacier Bay National Park
From the NASA Earth Observatory blog:
The sediment slid in a southeasterly direction, stretching across 7.4 kilometers (4.6 miles) and mixing with ice and snow in the process. The slide was triggered by the collapse of a near-vertical mountain face at an elevation of 2,800 meters (9,200 feet), according to Columbia University seismologist Colin Stark.
Stark first became aware that a landslide may have occurred when a rapid detection tool that sifts through data collected by global earthquake monitoring network picked up a signal indicative of a fairly significant event. The earthquake sensors detect seismic waves–vibrations that radiate through Earth’s crust because of sudden movements of rock, ice, magma, or debris.