On May 18, 1980, Mount St Helen's which is located about 100 miles south of Seattle and 50 miles northeast of Portland, Oregon.
In this episode, we will talk about:
- The Eruption
- Geology & Tectonics
- Five Volcano Facts
Why is this information helpful for preparedness?
Hopefully, you don't ever have to experience a volcano eruption. However, it’s good to understand the science behind it, even just some level of how rocks are formed, how nature happens around us. So when you're driving around, when you're out in the desert, you're in the mountains or you're going somewhere. you know enough about what you're looking at and you can say that might be a dangerous thing.
On May 18th, 1980 Mount St. Helens, which is located about 100 miles south of Seattle and about 50 miles northeast of Portland, Oregon, erupted. It's up in the Cascade Mountain range. And all that with Mt. Rainier, Mount Hood, a bunch other volcanoes up there when the eruption happened that resulted in the deaths of 57 people, along with this destruction of about 250 homes, nearly 50 bridges and hundreds of miles of roads.
They never found some bodies up there because in that gigantic wall of mud and boiling water and lava and all that stuff comes barreling down the side of the mountain hundreds of miles an hour. It doesn't leave a whole lot left in its trace so that they had some people definitely go back to nature that day.
Mount St. Helen's is less than 40,000 years old and the cone that blew in 1980 took over 2000 years to build. The USGS ranks Mount St. Helen's as the second most dangerous volcano in the United States.
Geology & Tectonics
Mount St. Helen's is a large cone made of layers of lava rock, ash, and other deposits.
Cascade Mountain Range is at the edge of the subduction zone, known as the Cascadia subduction zone of the Juan de Fuca and North American plates. A subduction zone is where one plate rides up over another. The Juan de Fuca plate is not a large plate as tectonic plates go.
The Cascade mountain range is part of the Ring of Fire known as the Cascade Arc, which consists of 160 volcanos. Yeah, 160 volcanoes in that little volatile corner of North America.
It is created on the floor of the Pacific Ocean where the Juan de Fuca Ridge rises out of the seafloor. The ocean floor spread to the east is the Juan de Fuca Plate and the rock that forms and moves west is the Pacific plate. Eventually, over millennia the North American Plate will ride over and grind the Juan de Fuca Plate out of existence. As a matter of fact, the Juan de Fuca Plate was originally a much larger plate know as the Farallon plate. Over time though, the North American Plate has ground it down so much it got a name change! (I don't really know that part and if someone listening knows all about it, let me know)
Five Volcano Facts
- Where does the name "volcano" come from? Vulcan, the Roman god of fire.
- Approximately how many people live within the danger zone of a volcano? Approximately 350-million people. 1 out of 20 on the planet.
- Magma and lava are technically not the same things. Magma is when the rock is molten inside of the volcano. Lava is the molten rock that is outside of a volcano.
- Lava can reach ~1250C or nearly 2300F
- ~1900 active volcanos on the planet with most located in the ring of fire surrounding the pacific ocean.
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