The1980 eruption reduced the elevation ofMount St. Helensfrom 9,677 feet to 8, 353 feet, a difference of about 1,314 feet. The lateral blast ripped through the debris at 300 miles per hour and at temperatures of 660 degrees Farenheit, scorching 14 to 17 miles of land from the crater.
In less than three minutes, 230 square miles of forest lay flattened. 86,000 square acres of trees were mowed down, the equivalent to 4 billion boards of timber enough to build 300,000 homes. Some scientists estimated the power of the blast to 1,000 atomic bombs.
The eruption produced a column of ash and gas that rose 15 miles into the atmosphere in 15 minutes. Over the course of the day, 520 million tons of ash covered 22,000 square miles. It spread across the U.S. in three days and circled the Earth in 15 days.