On May 18, 1980, Mt St Helens, a volcano in southwest Washington State erupted. The eruption caused billions of dollars in damage, and 57 people were killed. While it was not the worst volcanic eruption on record, it still was a shock. More than a few installment loans went into cleaning up, and Mt St Helens has been watched closely since.
Article Source: 30th anniversary of Mt St Helens eruption: May 18, 2010
Mt St Helens Eruption
Mt St Helens had been dormant for more than a century, but in March 1980, earthquakes began to shake the mountain. For the next two months, the mountain was closely monitored. On May 18, an earthquake with a magnitude of 5 on the Richter scale shook the mountain. The north face nearly collapsed in a landslide, which triggered a release of pressure culminating in an eruption. Gas, magma, rock and other debris blasted out of the side.
The Blasts
The pyroclastic (volcanic) blast that ripped through the side of the mountain as a result of the landslide reached the speed of sound. Materials ejected by the blast spread over 20 miles. Pyroclastic flows (material pouring out of the mountain) continued after the eruption, and 17 were observed afterward. The pyroclastic flows were still over 800 degrees Fahrenheit in temperature two weeks later.
Damage from the blast
A 20 mile swath of destruction flowed straight out of the volcano. Mud flows and debris were shot into river systems, causing floods and heavy damage to river systems. The volcano spewed forth over a cubic mile of debris. 200 homes, 27 bridges, 15 miles of railway and 185 miles of highway were destroyed, and 57 perished. President Jimmy Carter flew out to observe the damage and compared it to the surface of the moon.
Further fallout
An ash cloud extended 12 miles into the atmosphere. Washington State was covered with ash, with the city of Yakima getting a heavy coat by the next day. Spokane, Wash., was plunged into total darkness, with a visibility of about 10 feet. Ash was reported as far away as New Mexico and Minnesota. Countless flights were grounded at airports, just like the recent Iceland volcano eruptions forced airports to do. The blast was 1,600 times more powerful than the Hiroshima atomic bomb. The mountain was left over 1,000 feet shorter and with a crater almost 2.5 miles wide. Occasional smaller eruptions and activity have occurred since. Over $ 1 billion in damage was done by the Mt St Helens eruption. It serves as a stern reminder that nature is a harsh mistress.
Citations
Mt St Helens
http://en.wikipedia.org/wiki/1980_eruption_of_Mount_St._Helens
