That artical is not very factual. The eruption was caused by an earthquake landslide on the north face which caused the mountain to release its pressure laterally. The majority of the material was from 2 giant slabs of rock that slid one after another which resulted in the largest landslide in recorded history. During the landslide the walls of the verticle lava channel was weakened and the side blew out. The explosion launched chunks of rock the size of large houses over 5 miles and scattered them beyond where the observatory now sits. The landslide hit Spirit Lake and pushed the entire lake over 1000’ up the hillside.
I have been giving tours up in that area for years,I have been fascinated with that mountain since I was a kid, and it is one of my most favorite places to go. The destruction is impressive but at the same time gorgeous.
Excellent summary. Was there back in the day. Interesting subject, but rather absurd when shoe-horned into a narrow brand of religeous dogma.