Twenty years ago a massive sideways blast from Mount St. Helens vaporized forests in five thousand degree heat, flattened hundreds of miles of timberland, and killed 57 people, many of whom vanished beneath tons of ash. "We first thought it was a forest fire; then we knew it was the mountain." "You could see it burning and churning, kind of rumble. We were right under it." Scientists who watched it blow now say the eruption began with a modest earthquake which was enough to loosen the already unstable mountainside. Peter Lipman of the US Geological Survey says, "And that released the pressure that was holding the molten rock inside the volcano and then a number of seconds after they observed the landslide, they saw the first ash cloud come out and the big explosions begin." Mt. St. Helens stunned scientists with its ferocity; so much so that it is now the most studied volcano in the world. Peter Lipman says, "The events on May 18 involved an earthquake, a landslide, a horizontally directed explosion, a vertically directed explosion. And the resulting deposits are immensely complicated." Peter Lipman flew to Mt. St. Helens in the spring of 1980 to study what was then just a rumbling mountain. Fellow scientist and friend David Johnston died in the blast. Johnston is memorialized outside his old office with a chunk of the volcano he died studying. Now tourist helicopters fly over the volcano's edge. About three million people per year visit the one hundred thousand acre national preserve. Much of the land will look this way for centuries. But amid the dust, life returns and sometimes flourishes. Bob Andrew of the US Forest Service says, "It is beautiful. Wildflowers all over. We have lots and lots of wild elk and deer. In fact we have more deer than we had before." The fury of Mt. St. Helens has turned scientists' attention to Oregon's Mount Hood to the south and Washington's Mount Rainier. Both are geologic cousins. And both are capable of the same thing