The largest landslide in recorded history swept down the mountain at speeds of 70 to 150 miles per hour and buried the North Fork of the Toutle River under an average of 150 feet of debris. Some areas are covered by as much as 600 feet. I all, approximately 23 square miles of material was removed from the mountain.
Lateral Blast The lateral blast swept out of the north side of MSH at 300 miles per hour creating a 230 square mile fan shaped area of devastation reaching a distance of 17 miles from the crater. With temperatures as high as 660 degrees F and the power of 24 megatons of thermal energy, it snapped 100 year old trees like toothpicks and stripped them of their bark...
...As the north face of the mountain collapsed, expanding gases and steam from the molten rock hurtled rock and ash out across the land at speeds up to 670 miles per hour uprooting trees as far as 6 miles from the mountain. It was impossible to outrun and the searing heat too intense. Reid Blackburn, a photographer with The Columbian newspaper was one of the first victims of the eruption. Blackburn had tried to take shelter in his car but the lateral blast blew in the windows, letting in the hot, choking ash. He was found in his car 7 miles north of the mountain...
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