Mount Saint Helens, active volcano, southwestern Washington, in the Cascade Range. The volcano, which had been dormant since 1857, began to show signs of renewed activity in early 1980 when a column of magma (molten rock) began pushing up inside the mountain, causing the north face of the mountain to bulge out. On May 18, 1980, an earthquake caused a landslide on the mountain’s north face, taking off the top of the mountain. The landslide triggered the main eruption by “uncorking” the column of magma that had been building up. The eruption spewed a cloud of ash and gases as high as 19 km (12 mi). The release of the pressurized gases produced a turbulent blast of wind that knocked down trees and stripped their branches. The skies darkened as wind carried the ash-filled air over much of eastern Washington and beyond.
No comments:
Post a Comment