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Abstract
The explosion of Mount St. Helens In Washington State on Hay 18, 1980 was Initiated by an earthquake and rocksiide Involving one half cubic mile of rock. As the sum it and north slope slid off the volcano that morning, pressure was released inside the volcano where super-hot liquid water Immediately flashed to steam. The northward-directed steam explosion released energy equivalent to 20 million tons of TNT which toppled 150 square miles of forest In six minutes. In Spirit Lake north of the volcano, an enormous water wave initiated by one eighth cubic mile of rockslide debris stripped trees from slopes as much as 850 feet above the pre-eruption water level. The total energy output on May 18 was equivalent to 400 million tons TNT, approximately 20,000 Hiroshima-size atomic bombs. On Hay 18 and also during later eruptions critical energy thresholds were exceeded by potent geologic processes which were able to accomplish significant changes in short order. These processes challenge our way of thinking about how the earth works and serve as a miniature laboratory for catastrophisra.