how far did the landslide reach?
He traveled and moved across Spirit Lake's west arm, part of it hit a ridge about north, some of the slide spilled over the ridge, but most of it moved down the North Fork Toutle River, filling its valley up to deep with avalanche debris
1980 eruption of Mount St. Helens
 The landslide, the largest in recorded history, traveled at and moved across Spirit Lake's west arm. Part of it hit a ridge about north. Some of the slide spilled over the ridge, but most of it moved down the North Fork Toutle River, filling its valley up to deep with avalanche debris.
what happened after the mt st helens eruption An earthquake which caused the entire weakened north face to slide away, creating the largest landslide recorded when was the last time it erupted? January 2008 and before that? October 2004 and before that? Between 1980s to 1991 which was the deadliest eruption? March 27, 1980 eruptions describe the build up of this eruption that you just mentioned On March 20, at 3:45 p.m. Pacific Standard Time, a shallow magnitude 4.2 earthquake centered below the volcano's north flank, signaled the volcano's return from 123 years of hibernation. A gradually building earthquake swarm saturated area seismographs and started to climax at about noon on March 25, reaching peak levels in the next two days, including an earthquake registering 5.1 on the Richter scale. A total of 174 shocks of magnitude 2.6 or greater were recorded during those two days
wiki:20190489
1980 eruption of Mount St. Helens [SEP] Landslide and climactic phase
Part of it hit a ridge about north. Some of the slide spilled over the ridge, but most of it moved down the North Fork Toutle River, filling its valley up to deep with avalanche debris. An area of about was covered, and the total volume of the deposit was about . Scientists were able to reconstruct the motion of the landslide from a series of rapid photographs by Gary Rosenquist, who was camping away from the blast. Rosenquist, his party and his photographs survived because the blast was deflected by local topography short of his location.