MOUNT ST HELENS
In the spring and summer of 1980 a volcano named Mount St Helens suddenly and violently awoke after 120 years of inactivity. The volcano is located in the Cascade Range about 120 km south of Seattle, Washington.. On March 27 a huge new crater opened at the top of Mount St Helens, and steam and smoke poured out for the first time memory. The emissions continued sporadically for the next 51 days.
May 18 brought an enormous and devastating blast that drew the attention of all Americans on the erupting volcano. An earthquake registering about 5 on the Richter scale shook the north slope of the mountain. Gases within the mountain suddenly escaped with a force great enough to send a column of steam and volcanic ash 21,300 m into the air. No lava erupted, but the blast blew away the entire north slope of the once cone-shaped volcano. Trees in the way of the blast were blown down like match sticks. Torrents of boiling mud and water, traveling at over 320 kilometers an hour, flowed down the mountain into the Toutle River and eventually into the Columbia River. Seventy people died or were declared missing because of the blast. More than ll million fish died in the heated water of the rivers. Thousands of birds and animals also died.
Prevailing winds picked up volcanic ash from the eruption and carried it eastward across the Cascades. The ash-choked skies reduced visibility to zero in Yakima, Washington, and other nearby cities. Road and rail traffic came to a standstill. Airplane travel within a radius of several hundred miles was canceled. A 5-centimeter layer of ash blanketed the land as far away as ldaho. Smaller particles stayed aloft in the air surrounding the entire earth during the next 17 days.
Mount St Helens looked like a completely different place, when after four more big blasts, it finally became quiet. It had a different shape, a lower elevation, and upper slopes that were totally devastated. Yet life began to return to the mountain immediately. Within a week, spiders busily spun webs. By the end of the summer ferns, other ground covers, and even trees sprouted from the ashes.
Peace and quiet once again prevail in the scenic Cascade Range. But the mountains, located on the North American plate, lie directly above the descending edge of the Juan de Fuca plate. Will it happen again? Geologists fear that another eruption will occur somewhere in the Cascades in the near future.
MOUNT ST HELENS