On today’s blog we will be discussing the deadliest volcanic eruption in US history, We will also be discussing another volcanic eruption that killed over 500 people in the late 1700’s from the most active volcano in the world which is also now located in the US.
Before we get into the nitty gritty of the Mount St Helens eruption, let’s first discuss a little bit about volcanic eruptions. Just like with tornados and hurricanes, volcanic eruptions have a scale. This scale called VEI for volcanic eruption index ranges from 0 to 8 with 8 being the strongest eruption. There’s a lot of scientific mumbo jumbo that goes into measuring the eruption. One of which is how high the ash and other particles are launched into the sky.
The western United States is in the Pacific Ring of Fire that stretches almost 25,000 miles. It is here in the Ring of Fire that the Pacific tectonic plate connects with other continental plates causing a lot of movement within the plates. More than 450 volcanoes (75% of the worlds volcanoes) can be found in the Ring of Fire. 330 volcanoes are in the US but only 161 are considered active. SO here is a random fact I found while researching that I thought you guys might enjoy. There are actually 3 extinct volcanoes in Missouri and 1 in Illinois, which I found interesting. Now that we have a little background into volcanoes and where they are located, let’s discuss Mount St Helens.
Mount St Helens
First let’s discuss where Mount St Helens is. The still active volcano is a little less than 100 miles south of Seattle Washington. A smaller town called Cougar is located about 11 miles away. Otherwise near to the volcano are 3 different rivers and a wide forest area. Scientists believe that Mount St Helens is one of the youngest volcanoes in the Cascade mountain range, only dating back to about 40,000 years old with the cone of the volcano dating back only 2,200 years.
In March of 1980, the area around Mount St Helens experienced earthquakes and small steam eruptions. By April the mountain had developed a bulge on the North side which would cause a devastating avalanche on May 18 when another large earthquake would strike. The bulge on the north side blew and caused the earth’s largest debris avalanche. This avalanche would travel about 14 miles westward. The landslide caused the crypto dome, or the magma filling, to be depressurized. This caused the massive explosion of rock and ash along with pyroclastic blasts to be released. Pyroclastic blasts can be thought of as extremely hot steam and ash like wind. The ash and rock explosions continued for over 9 hours and reached a height of 16 miles. The craziest part to me was that winds picked up approximately 520 million tons of volcanic ash across the United States as far as 980 miles westward (with a substantial amount). People as far as reported a light amount of ash falling along with a small portion of Oklahoma. A total of 57 people died.
If you are interested, I suggest looking up pictures of before and after the volcanic eruption because it is interesting to see. Along with that, this eruption is what helped a lot of geological data to be used to help predict and observe volcanic eruptions. After the 2 months of earthquakes and small eruptions, scientists were able to get close to the cone of Mount St Helens and observe an active volcano closer than they ever had before. It helped scientists be better able to identify early warning signs of an eruption. It really did a lot for volcanology.
Keanakakoi Eruption
So the next eruption we are going to briefly talk about is the Keanakakoi eruption of 1790. This is the volcano in Kilauea that is often seen in the news with just lava flowing from it. And now that is pretty much all that happens to this volcano but prior to the 1800’s Kilauea’s volcano had some pretty forceful eruptions like that of Mount St Helens and the eruption that happened in 1790 is now considered the worst in US history, but of course there is some conflict due to it not being the US at the time. Either way, today we’ve talked about the top 2 deadliest in US history.
Gena’s Macabre Moment
Upon my research, I found that there was actually a battle going on for possession of the land between 2 tribes. The battle over the land had been waging for a few years and the one tribe of the new king of Hawaii had just won. Just like Mount St Helens it was hard for people to flee because of the pyroclastic blasts along with the rock and ash. Over 500 people are believed to have died in the eruption with 80 to 100 being from the King’s tribe that happened to be passing by the crater when it erupted violently. There honestly wasn’t much about this eruption but the death toll was pretty high so I wanted to throw the info in. The VEI (volcanic eruption index) was a 4 where Mount St Helens was a 5. Some other interesting info I found was, the highest VEI in the US is 6 back in 1912. This eruption killed only 2 people though. It’s called Novarupta in Alaska and was a new volcano when it erupted.
Now the Kilauea volcano still erupts but only with slow moving lava flows which are very common in Hawaii and referred to by some as “Hawaiian eruptions” when discussing other eruptions like that found in Hawaii. Scientist have been closely monitoring Kilauea’s volcano for the past few years to determine when, why and how some of it’s eruptions were so violent in the past. And thanks to Mount St Helens they have a better understanding.
And there you have the high story of Mount St Helens! Thanks for reading!
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