Mount St. Helens

An account of the day St. Helens erupted with some background information on the volcano and some preventative measures.

Mount St. Helens volcano is in Washington State, North America. It is on the San Andreas fault line, and last erupted at 8:32 am May 18th 1980.

An earthquake that measured 5.1 on the Richter scale caused the north face of the mountain to collapse, this caused a huge avalanche of rubble to cascade down the face, this also blew down 230 square miles of forest. The earthquake triggered a mushroom shaped cloud of ash which turned the sky dark, and travelled around the world reached all around the globe in the atmosphere causing the sky to go dark. The earthquake lasted nine hours and drastically changed all of the area around it.

Mount Saint Helen got it’s name from the English Lord St Helens. It is classified as relatively young, it is less than 40,000 years old. It is 9,677 feet tall.

The 1980 eruption was caused by an earthquake on the San Andreas fault line, it made the north side of the volcano collapse, this happened after many events that were leading up to it, including the formation of a large bulge at the Northern summit. All of the north side cascaded down in the largest landslide in history. The first cause of this was a 4.1 earthquake, which caused steam to billow out from the top, effectively weakening it for the later 5.1 which tipped it over the top.

There was no official one sign that could have predicted the eruption, however there were many small signs, such as the progressive earthquakes, and a bulge that formed on the side of the mountain, which was continually getting much larger, until the last few hours before the quake, where it slowly got slightly smaller, then bigger, almost like it was breathing. There was an observation area set up around three miles from the summit, where geologists Harry Truman and David Johnstone were observing the peak. At the time of the eruption David Johnstone was looking at the summit, and died just moments after the peak collapsed.

Many of the citizens of the surrounding area of Spirit Lake in Washington State didn’t want to have to evacuate, because they wanted more evidence that something was going to happen. The night before the eruption the residents who had been evacuated were allowed back into their houses to retrieve their possessions. They were asked to be back before sunset, but many didn’t want to come back so stayed in their houses. Some residents refused to evacuate entirely, claiming that the mountain would never hurt them, they received much interest from the press, one man claimed that “if the mountain blows, I’ll just climb into an old mine shaft with a crate of whisky”.

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