Dwight R. "Rocky" Crandell (1923 - April 6, 2009) was an American volcanologist who alongside Donal R. Mullineaux correctly predicted that Mount St. Helens would erupt before the end of the 20th century.
Born in Illinois, Crandell fought in World War II as a lieutenant in an Army mortar platoon. Once the war had finished he returned to America and earned a doctorate from Yale. It was then he was placed at the USGS office in Colorado. Crandell and Mullineaux, who met at the offices then began to work on the theory that Mount St. Helens will erupt.
The pair proved that about 5,600 years earlier, the summit of Mount Rainier had collapsed and caused a landslide filling some valleys up to 400 feet deep. That awakened the recognition that a similar event could endanger hundreds of thousands of people living atop the ancient mudflows. They went on to write the 1978 report that claimed Mount St. Helens is “an especially dangerous volcano” and it would more than likely erupt before the end of the 20th century.
On May 18, 1980 their predictions came true when the volcano erupted killing 57 people and caused more than $1 billion worth of damage. He retired shortly after the eruption.
Crandell died in a hospice in Colorado on May 6, 2009 after suffering a heart attack. He is survived by his two children. His wife died in 2006 and her ashes were scattered at Mount Rainier where he had worked many years before.