Store Subscribe via RSS IconRSS or e-mail About this Site Link To Us Sites We Like
Legal Stuff Privacy Policy

category icon

The Mount St. Helens Eruption

Posted by Big Boo on May 21st, 2009

mount-st-helens-before-during-afterI’m sure it was by no means the first volcano to erupt during my life time, but the Mount St. Helens eruption in March 1980 was the first I remember.  For someone coming from the UK the closest I ever got to a volcano was reading about them in books, so when Mount St. Helens erupted this was my first chance to see how truly destructive a volcano could be.

Mount St. Helens had lay quietly since the 1850’s but 130 odd years worth of liquid rock magma had been building up beneath the surface.  In early March 1980 there were a number of earthquakes which were to herald the beginning of the eruption, until on May 18 the pressure got too much and the volcano exploded.

The explosion was so great that tons of dust and rubble were shot over 2km into the air, and the peak of the mountain was completely destroyed, leaving behind a crater over 70m wide.  Over the next few weeks the volcano would continue to erupt, with the crater eventually becoming 365m wide and 150m deep.

The worst was still to come though.  Thousands of tremors occured over the next few weeks, until on May 18 when a large tremor caused the north side of the mountain to collapse, causing a landslide that finally stretched out for 17 miles.  This landslide cleared the mountain area enough that the volcano erupted again, sending out a new column of ash and incredible 12 miles into the air in less than 10 minutes.  Combined with the wind, ash was carried more than 90 miles from the site of Mount St. Helens.

Luckily the area was sparsely populated, and most people had been evacuated, but 57 people were killed and more than 200 homes destroyed, as well as bridges and many miles of railway and road.  Further out some of the major highways were closed for more than a week due to restricted visibility from the cloud of ash.

The volcano continued to erupt from time to time until October 1980, but even after that the volcano is still not quietened down.  New domes caused by the magma pushing up through the earth have been occuring regularly, with another flurry of eruptions between 1989 and 1991, and the most recent dome started to form in 2004 before erupting in 2008.  Whilst it is now probably unlikely to erupt with the same severity it had in 1980, I for one wouldn’t feel comfortable straying too close to the area, just in case…