WASHINGTON,- On May 18, 1980 Mount St. Helens was shaken by an earthquake measuring 5.01 on the Richter Scale. It was strong enough to dislodge a bulge of magma and create an eruption.
The Mount St. Helens disaster killed 57 people, destroyed 250 homes, and demolished hundreds of miles of wilderness and highways. Nearly all vegetation within 12 miles was leveled and a mushroom cloud of gas and ash rose over 12 miles into the air above the peak.The mountain stood more than 9,600 feet before the eruption, but is now some 1,700 feet shorter.
The 8:32 a.m. eruption sent a 10-mile-high plume of dark ash into the air and toward Central Washington. By 10 a.m., the first cloud of gray grit rolled into Yakima, turning day into night. Within a half-hour, the Yakima airport was closed. Interstate 90 quickly followed suit, as did all major routes in and out of the city.
Telephone service was spotty as callers jammed lines. Most people wisely got off the roads, going home or to emergency centers set up at school gymnasiums and churches, or to tourist lodges, community halls and police stations. By nightfall, only two minor injury accidents had been reported.