This was the first "disaster" movie I recall seeing when I was about 13 and I still watch it every chance I get. The film combines real news footage of the actual eruption with re-enacted chaos, leaving the viewer with some idea of what it must have been like at ground zero. The scientist character is indeed based on a real scientist who camped out at the North side of St. Helens. His love interest may be fictional but it adds a human touch to his character. And Art Carney is very funny and warm as Harry Truman. No gore, no senseless violence or gratuitous sex scenes....I like this movie.