When Mount St. Helens erupted, this debris avalanche traveled 15 miles (24 km) and generated enough material to cover Washington, D.C. to a depth of 14 feet (4 m). The avalanche exceeded 150 miles per hour (240 km/hr).
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When Mount St. Helens erupted, this debris avalanche traveled 15 miles (24 km) and generated enough material to cover Washington, D.C. to a depth of 14 feet (4 m). The avalanche exceeded 150 miles per hour (240 km/hr). |
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