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62 Cards in this Set

  • Front
  • Back
Where do volcanoes form?
Subduction zones, hot spots, spreading centers, plate edges
Why are volcanoes that form due to subduction andesitic and not basaltic?
Water carried with the plate lowers the melting point, so the continent melts as the magma rises, changing it's composition
What does SiO2 have to do with the type of eruption?
More SiO2=More explosive
Viscosity to do with an eruption?
More=more volatile
Dissovled gasses to do with an eruption?
More=more explosive because temp decreases=more solubility
Where do the most explosive volcanoes form?
Subduction zones
What makes volcanoes at subduction zones more explosive?
Lower melting point=higher SiO2, H2O content, viscosity, and gases
What three things generate an eruption?
Low Pressure, temperature rises, water content increases
6 types of volcanoes
Shield, Cinder/Scoria, Composite/Strato, Fissure/Flood, Lava dome, caldera
6 types of eruption styles
Vulcanian, Plinian, crater collapse, icelandic, hawaiian, stromboilian
Where is crater lake? How did it form?
Oregon, Mt. Mazma roof collapse
Volcanoes and eruption styles at spreading centers?
Fissure, flood. Stromboli and icelandic
Volcanoes and eruption styles at subduction zones?
Composite, vulcanian, plinian, caldera
3 cascade mountains and the one that has erupted the most in the past 4000 years
Mt Rainier, Shasta, Lassen Peak; St. Helens
How do we know the age of eruptions?
Radiocarbon dating of the surrounding trees
Describe the eruption of Mt. St. Helens
Earthquake caused a lahar, which released pressue and caused a lateral pyroclastic flow followed by a plinian eruption
Why are Shasta and Rainier eruptions so dangerous?
Lahars, high populations
Ways a volcano can kill you
Bombs, pyroclastic flow, lava flow, lahar, acid rain, landslide, gases
How does a P flow work and why is it so dangerous?
hot ash/gas/air flowing at high speeds
What makes a Nuee Ardente different from a pyroclastic flow?
It glows because it's incandescent
What causes a mass movement?
External causes of slope failure
Material pulls away (tear away) or accumulates (pile up)
Internal causes of slope failure
weak material
reduced cohesion
Adverse Geologic Structure
Inherently Weak Material
Small, book like structure
Water fills pores and dissolves rocks or erodes loose material
Reduced Cohesion
Rock is compressed, then expands when compressor is lifted.
Adverse Geologic Structure
Ancient slip surfaces
Rock Layer Orientation
Rock Weakness
Mass Movement Triggers
Heavy Rain
Thawing of frozen ground
Quick Clay
clay flour+salt from glaciers. Gets lifted above sea level, water removes salt which makes it weak
Sink hole creation
Collapse into void, vertical downward movement, move as separate blocks
Sea on the moon
Why are few impacts visible on Earth?
orbit far past outer planets in the Oort Cloud
Inner planets/asteroid belt
Meteroide vs. meteor vs. meteroite
-or=in atmosphere
-ite=hit earth
Rate of impact
100,000/24 hours
How are we protected?
The atmosphere acts like a solid
Where is meteor crater?
Evidence for meteor impacts?
No local volcanoes, steep sides/rim, no sinkholes in area, high temp and pressue minerals found, fused sand
What is the K/T boundary?
Crutaceous/Tertiary iridium boundary
Life after an impact
Acid Rain
Global Warming
Crater forming process
Impact, melts, debris, vapor
Torino Scale
Rates possible impacts 0-10
Non-explosive, basalt, shield
Non explosive, basalt, shield
Low explosions, basalt to slight andesite, scoria/cinder
Moderately explosive, basalt to rhyolite, scoria and strato
Highly explosive, andesite to rhyolite, strato
Highly explosive, andesite to rhyolite, caldera
Shield/Flood Basalts
Low viscosity, low volatiles, large volume
Low/med viscosity, med/high volatiles, small volume
med/high visco, med/high vol, large volume
Lava Dome
high visco, low vol, small volume
high viscosity, high volit, large volume
Slow and dry
Fast and dry
Transitional Slide
rapid and moist
Rotational Slide
slow and moist
Rapid and saturated
Snow avalanche
Rapid and moist
Rapid and moist
Debris flow
Rapid and saturated