The Eruption of Mt. St. Helens

Mount St. Helens. One of the most (if not \*the\* most famous) volcano in the United States.

And the reason for it is because it had a massive eruption in the year 1980, and still to this day it remains the biggest eruption in the history of the USA.

But what is the mountain about, and how exactly did it erupt? Well, this is what this page will try to cover.

## The Volcano

Mount St. Helens. It is a Volcano that formed around 40,000 years ago and before it's infamous eruption had a height of around 9,000 Feet. During the era of Exploration and Colonization, the British came to the Pacific Northwest and discover the Cascades, the Volcano was then visited by a British Naval captain named Baron St. Helens, and his crew decided to name the Volcano after him.

The Native Americans would also admire (and fear) the Volcano for its symmetrical cone shape,  the ancient glaciers and the wilderness around it, as well as its constant eruptions. When the area began to develop, people would flock to the Volcano for vacation, camping, and even hiking expeditions.

## Disaster

The first stages of the Mount St. Helens disaster began on March 20, 1980. When seismometers planted at the Volcano detected a subterranean Earthquake measuring around 4.1 on the Richter Scale. This would usually tell the seismologist that a Volcano is about to wake up.

Mount St. Helens is a part of a Volcanic Zone known as the *Cascades*, and because of the Cascadia Subduction Zone (when one tectonic plate slides underneath another) it sometimes forms volcanoes, and these type of volcanoes can erupt gasses, hot rock, ash and even debris flows which are known to geologists and volcanologists as *"*Lahars*"* which can cause extensive damage and perhaps even kill people and wildlife. Sometimes, these kinds of Volcanoes can erupt so violently they can cause even more death and destruction.

According to the graph above, Mount St. Helens has erupted around 14 times, which is more than any other Cascade Volcano.

Around a week after the first recorded Earthquake, the USGS (United States Geological Survey) has detected a gas explosion from St. Helens, that meant the volcano is once again active. The last eruption from St. Helens before 1980, was 1867 (around 123 years).

Geologists and Volcanologists from around the world came to experiment on the now active St. Helens. Gathering information as they collect rocks and volcanic gases around St. Helens. Geologists and Volcanologists also kept watching the Volcano to see if it was going to erupt.

Before 1980, the largest eruption in the US was another Cascade Volcano: *Lassen Peak* which had a pretty big eruption, in fact, it also threw out a huge rock (on the lower-left corner of the picture above, around 6 miles away from the volcano.

Pretty soon, the media got close to the active Volcano and try to get coverage on what the volcano is doing, with no care or thought of the dangers St. Helens presented.

As Geologists and Volcanologists try to gather information, they were having a hard time. They're not seeing a large number of volcanic gases which is typical before a particularly large eruption. It was also the Earthquake patterns too, typically when magma (lava) rises underneath a volcano, the Earthquakes increase, but the Earthquakes were decreasing at St. Helens.

As the scientists at St. Helens were beginning to lose hope of seeing a large eruption, in Mid-April, they noticed that the shape of the Volcano was changing. The North Side was beginning to swell. This is caused by underground lava and is causing the Volcano to change which is known as a "Cryptodome", this can also be called the "Volcanic Bulge", it would crack ice and snow well above the timberline. The Bulge moved out at around 5 feet per day.

This is when scientists discover that the bulge is pressure building inside the volcano, which is a high tale sign the volcano is going to erupt.

This is where Washington State's Governor Dixie Lee Ray announces a mandatory evacuation of any town or other establishments close to the Volcano, and restricted recreational camping around the Volcano too. Though, for some evacuees, it was difficult since they don't want to leave their home or possessions behind.

Meanwhile, back at Mount St. Helens, Geologists continue to monitor the Volcano and the bulge.

On May 17, Geologist David A. Johnston set up camp at Coldwater Creek, 5 miles from the Volcano.

The Next Morning on May 18. A seismometer has detected a 5.1 Earthquake at 8:32 AM. This greatly affected the bulge on the north side, but after it rippled like gelatin, that bulge then slid right off.

Then the north side exploded. This created the largest landslide recorded by humans. Soon, the landslide would be overtaken by the Lateral Blast which would scorch the forest nearby and for the next 10 miles. Trees became scorched, and the ground petrified. The scene was horrific.

Around 40-45 minutes later. The initial eruption occurred as a humongous eruption cloud went up around 45,000 feet into the air producing ash that not only stripped the area of air but also rubbed against the positively charged air particles (as ash is negatively charged) which caused lightning bolts as well as fires.

The Volcano would continue to erupt for around 9 hours.

But after the eruption, the devastation was clear.

The sense of devastation from St. Helens was indeed clear (especially once the air got clear again) The Eruption sucked Spirit Lake dry, the Lateral Blast destroyed everything in its path (e.g., Trees Wild-life and perhaps humans) St. Helens also produced Lahars that clogged the nearby rivers.

The ash cloud was so huge that the ash itself extended to around 10 states which affected air travel.

In the days of search and rescue followed, the National Guard also had a very hard time getting survivors out due to the air still being filled by ash and volcanic gases (which can disable any kind of aircraft from Helicopters and even jetliners).

In total, Mount St. Helens killed 57 people (which included Geologist David Johnston and an Innkeeper Harry \*R\* Truman)

You see, it's Harry \*R\* Truman, not Harry \*S\* Truman.

But anyway, 200 structures (e.g., Homes, Bridges, and whatnot) were destroyed as well as 250 miles of the surrounding countryside, Trees and Wildlife didn't survive. The eruptions may even cause indirect death and destruction from ash and gas inhalation.

The eruption of Mount St. Helens remains the largest and most destructive volcanic eruption in the history of the USA. It could only be a matter of time before another Cascade Volcano erupts again, and maybe far worse than St. Helens' eruption.

Want to know about the Hindenburg? just click here.

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