Eruption of Mount St. Helens.
In 1980, a major volcanic eruption occurred at Mount St. Helens, a volcano located in state of Washington, in the United States.
An eruption column rose 80,000 feet (24 km; 15 mi) into the atmosphere and deposited ash in 11 U.S. states. At the same time, snow, ice and several entire glaciers on the volcano melted, forming a series of large lahars (volcanic mudslides) that reached as far as the Columbia River, nearly 50 miles (80 km) to the southwest. (source)