Link #66: Mount St. Helen’s 1980 Eruption Was Equal to 500 Atom...

Link #66: Mount St. Helen’s 1980 Eruption Was Equal to 500 Atom Bombs!

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Link #66: Mount St. Helen’s 1980 Eruption Was Equal to 500 Atom Bombs!

MtStHelens_Mushroom_Cloud
The May 18 eruption. Composite photograph from 35 miles (60 km) west in Toledo, Washington. The ash-cloud stem is 10 miles (16 km) wide, and the mushroom top is 40 miles (64 km) wide and 15 miles (24 km) high. Image credit: Rocky Kolberg cc3.0

Mountains are some of the most majestic features of our planet. Their size and height are enough to make people wonder about their role in the world. If reading our last post on the three tallest mountains on earth made you say ‘wow’, then you haven’t come across information on the last great eruption of Mount St. Helen.

The last great eruption of Mount St. Helen occurred in 1980 and the force it generated was equal to 500 atom bombs! This means that the blast from this mountain on that fateful morning was equal to 500 Hiroshimas!

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What Happened When Mount St. Helen Erupted?

MSH82_st_helens_plume_from_harrys_ridge_05-19-82
3,000 ft (1 km) steam plume on May 19, 1982, two years after its major eruption. By Lyn Topinka PD image

Before its great eruption in 1980, Mount St. Helen had been dormant for 123 years. It is located on the famed Ring of Fire that almost surrounds the Pacific Ocean. Mount St. Helen also happens to be the most active and youngest Cascade Range Volcano on the planet.

In 1980, about two months before erupting, Mount St. Helen had vented ash and steam. This event made scientists and authorities become careful about what would happen. A little less than two months later, an earthquake measuring 5.1 on the Richter scale shook Mount St. Helen.

The earthquake resulted in a chunk of the mountain’s northern face falling away. The falling away of the mountain’s northern flank is considered to be the largest landslide in human recorded history. The opening caused by the earthquake and the landslide resulted in the release of pent up pressure. The effect was a volcanic eruption equal to about 500 atom bombs in magnitude and intensity.


How Much Damage Did Mount St. Helen Cause in 1980?

St_helens_map_showing_1980_eruption_deposits
Map of the area around Mount St. Helens which were affected by the May 18, 1980 eruption. North is to the top. PD-USGOV-INTERIOR-USGS.

Mount St. Helen’s eruption in 1980 was one of the most devastating events in human history. While one of the reasons that the Mount St. Helen eruption was so severe was its intensity, the main reason was that it was a lateral eruption. This means that the volcanic material was propelled as much horizontally as vertically.

The ejected volcanic material travelled at a speed of almost 500 kilometres per hour with temperatures achieved being more than 300 degrees Celsius. That eruption ended up destroying almost 600 square kilometres of forests in its path.

The ash released spread over almost 57,000 square kilometres and circled the whole planet in a mere 17 days. 57 people and numerous animals died due to the eruption too.


What Is the Ring of Fire?

Pacific_Ring_of_Fire
The Pacific Ring of Fire. By Gringer PD image

The Ring of Fire is a region that roughly spans islands and coasts on the western and eastern ends of the Pacific Ocean. This means that it stretches across the eastern coasts of Asia and Oceania through to the western coasts of North and South Americas.

The Ring of Fire is crucial to earth’s history because it holds 75 percent of the world’s volcanoes and sees 90 percent of all the earthquakes occurring in the world. The Ring of Fire was formed, and is kept active, by tectonic forces between multiple tectonic plates. It is, essentially, the most seismically active region in the world.




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Sources:

http://www.mtsthelensinfo.com/about
http://en.wikipedia.org/wiki/Ring_of_Fire
http://www.icr.org/article/mt-st-helens-catastrophism/
http://ngm.nationalgeographic.com/print/1981/01/mount-st-helens/findley-text

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