Video #6 -Mt. St. Helens - Back from the Dead
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Geology
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Apr 3, 2024
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Geology 115 – Volcanoes
Video #6: Mount Saint Helens – Back from the Dead
Instructions: Watch the video Mt. St. Helens – Back from the Dead
which can be found on YouTube (
https://www.youtube.com/watch?v=clCxpKuglho
) or look for the embedded video on Canvas in the Video Assignment Page.
It is put out by PBS NOVA and is approximately 52 minutes long. Use this handout to take “notes.” Submit your answers through the online “quiz” on Canvas. 1.
What the key question?
2.
Before 1980, how long has Mt. St. Helens been quiet? 3.
How many people died in the 1980 eruption? Some were up to ___ away in areas that were considered safe. 4.
4 miles from the volcano, the enormous Spirit Lake. How many feet did the avalanche lift the lake bed? 5.
The eruption was so powerful it altered the shape of the volcano. Before the 1980 eruption, it was a typical ____ volcano known as a stratovolcano.
6.
How many feet have been torn from the side? How big is the crater? 7.
Extra Credit: Explain why pressure and friction does melt rock to generate magma in a subduction zone.
8.
What organisms was found emerging from the ash? 9.
By fall, the volcano is still active. What else is happening besides the steam and ash? 10.
Scientists install a time elapse camera on a nearby ridge. Over several days, the pictures show a ____ rising in the middle of the crater floor. What is oozing out? 11.
What plant do they find in the spring of 1981 in the pumice plain? 12.
Geologist set up instruments to monitor what’s going on, including seismometers that can detect ____ set of by magma as it forces its way through the rocks. 13.
How long does the dome building last? 14.
3 years after the eruption, there is crucial discovery at Spirit Lake. What is it?
15.
On September 2004, the seismographs at the Cascades Volcano Observatory pick up a new series of ____ deep below Mt St. Helens
16.
During the next 2 weeks, there are 3 eruptions of ___.
17.
What do geologist see inside growing out of the crater floor?
18.
There is one urgent question: is the volcano building up to another major eruption? This proved difficult to answer. Lots of discussion occurred trying to answer if this was going to be an explosive eruption or whether it was going to be a dome building eruption. There is one way to find out. What is it?
19.
Pallistor starts with lava that erupted explosively in 1980. He is struck by the large areas of blue. What are the blue areas? 20.
What is the most important question do volcanologist have to answer? 21.
How old are the light grey, yellow, and pink rocks? 22.
Near the top, you see darker colors. When did those rocks begin erupting? 23.
By looking at the stratigraphy
of rocks exposed in the crater walls, we can piece back the puzzle and understand the ____ history of Mt. St. Helens.
24.
By studying the stratigraphy, it would seem Mt. St. Helens has one massive eruption every 1,000 years. That would imply the next really big one is not due for another century. Except for one little detail. Around 500 years ago, what was discovered? 25.
Mt St Heles can pause for a ____ years between big explosive eruptions or can pause for ___ years. 26.
Mt St Heles will erupt again. The only questions are ____ and how ___ that eruption will be.
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