On May 18th in 1980 Mount St. Helens erupted in Washington. This eruption caused a huge avalanche, and ash from the eruption fell as far away as Minnesota.
Throughout April, scientists watched a bulge on the north side of Mount St. Helens grow larger and larger. Finally, on May 18 at 8:32 a.m., a sudden 5.1-magnitude earthquake and eruption rocked the mountain. The north side of the peak rippled and blasted out ash at 650 miles per hour. A cloud of ash, rocks, gas and glacial ice roared down the side of the mountain at 100 mph. Fourteen miles of the Toutle River were buried up to 150 feet deep in the debris. Magma, at 1,300 degrees Fahrenheit, flowed for miles. (http://www.history.com/this-day-in-history/mount-st-helens-erupts)