Mount St. Helens We are here

What Mt. St. Helens looks like now…

What Mt. St. Helens used to look like…

In 1980 Mt. St Helens erupted http://www.youtube.com/watch?v=-H_HZVY1tT4

What observations can be made about the eruption? Write Mt St Helens observations on the top half of the front of your folded organizer Discuss with your table groups the observations you made Be prepared to share these with the whole class

Class Observations - -before erupted stratocone volcano -5.8 earthquake rumbled volcano right before -loss of life: bugs, 100’s of species of birds, 57 people, wildlife -pyroclastic flow, lahar -1300 ft torn off summit, mile wide crater -moved lakes -largest North American eruption in 100 years -north side collapse -5.1 earthquake -huge landslide, ash and steam into the air -wildlife killed, 57 people died -ash cloud covered over 100 miles, miles high as well -spirit lake moved 200 feet up -explosion heard 100’s of miles away -rumbling a few weeks before eruption -pyroclastic flow

What are some ideas as to why this eruption happened? There was an explosive volcanic eruption because… There was an explosive volcanic eruption because….. Gases and magma built up inside the mountain, earthquake caused it to be pushed out Earthquake cause pressure inside to become too much There was magma and an earthquake There was plate movement, divergent, causing the eruption Earthquake triggered landslide Heat and pressure became too much Pressure led to plate movement Plate movement, earthquake, eruption (per. 1) There was an explosive volcanic eruption because… earthquakes and friction caused the eruption the plates overlap each other and converge and that caused eruption magma (and maybe ash too) built up and pressure built up , then erupted pressure/eruption caused earthquake There was an explosive volcanic eruption because… massive pressure built up from convergent plates pressure caused by friction in the earth from spinning, -->heat--> gasses pushing up earthquake made it crumple and then pressure could release earthquake casued collapse, which allowed magma to overflow

Initial explanations…. This is only the first draft, and we will be making revisions as we learn more about volcanic eruptions As a table group, use our list of observations and ideas to write an initial explanation to explain why Mt St Helens erupted explosively

Class Observations 57 people killed Eruption went up and out- very big Huge earthquake, rumbling Eruption changed the shape of the mountain Huge ash cloud Killed a lot of life- 57 people, deer/elk, insects, squirrels, birds, wildlife Nearby land covered in ash Avalanche flattened forest, pyroclastic flow Trees in blast radius got incinerated Lake turned black Material moved fast, eruption happened fast Lake was raised, landslide (per 1.) 57 people killed Earthquake, landslide, prior to eruption Wildlife killed Poisonous gases, hot steam, landslide Ash went mostly to one side, in one direction 1300 ft of the mountain was blown off Pyroclastic flow- Spirit lake was dislocated and smothered- lake bed was raised Cone shaped and changed shape of the mountain Really large, went high upto sky, went outward covering ground too