Fissure: Eruption when a crater lake has an earthquake and lava begins to flow through itFissureMeltingCreates a Crater Lava LakePart of a cascade range on the west coast (Washington)-Ocean-Continent Convergent Plate Boundary○High Silicon = High Stickiness○Cone Type: Composite Cone○Known for explosive volcanism -After it went off, a majority of the mountain disappeard-Earthquakes○Grew @ 2 meters per day○David Johnston was the man who died observing the explosion○Mag 5 earthquake the morning it erupted and generated a landslide○Pyroclastic Flow○How did they know it would go off?-With the pyroclastic flow, they melted quickly and created a mud mixture○Lahars -what this volcanic mud flow is known by○What happened to the glaciers on the mountain?-Mount Saint Helens Today:-Mount Saint HelensCrater LakeLava DomeHigh SiliconMarch 5Monday, March 10, 2014 8:40 AM Class Notes Page 1Formed from Mt. Mazama-Happened about 6600 years ago-Forms by action like a plunger -Caldera (collapse of mountain)-Crater LakeMt. Mazama Before:Mt. Mazama After:Liquid RockHigh SiliconCrater Lake Created after Collapse of Mt. Mazama after earthquakes Caused cracking in the mountain Class Notes Page