Test 4 Flashcards
Divergent tectonic plates have _____ volume, _____ eruptions
high volume, gentle
Convergent tectonic plates have ____ volume, _____, ____ eruptions
low volume, periodic, violent
What are “Hot Spots”?
Volcanic activity in the interior of a tectonic plate
What is a rising plume of hot mantle material that is stationary?
A hot spot
When Oceanic crust is involved, a hot spot creates what?
Constant, high volume, gentle eruptions
When a continental crust is involved, a hot spot creates what?
Very periodic eruptions, extremely violent
Yellowstone National Park is a _____ crust volcano
continental
Hawaii is a _____ crust volcano
oceanic
What is the term for stuff that comes out of a volcano?
Ejecta
What are the 4 gases that come out of a volcano?
Steam, Sulfur gases, acidic gases, carbon gases
What are the 3 things that come out of a volcano?
Gases, liquids, pyroclastics
wHAT ARE THE TWO FORMS OF LAVA?
Pahoehoe and Aa
What are the characteristics of Pahoehoe lava?
Low viscosity and a smooth, ropy appearance
What are the characteristics of Aa lava?
High viscosity, broken, jagged appearance
What is the composition of Felsic lava?
Rhyolitic, >65% silicon, very viscous, Aa only, high gas content, explosive eruption
What is the composition of Intermediate lava?
Andesitic, 55-65% silicon, Medium viscosity, Aa only, medium gas content, medium eruption
What is the composition of mafic lava?
Basalitic, 45-55% silicon, low viscosity, pahoehoe or Aa, low gas content, gentle eruption
What controls viscosity?
silica
What controls gas content?
viscosity
What controls explosion?
gas content
What are pyroclastics?
solids released during an eruption
What are the sizes of pyroclastics?
dust, ash, lapilli, bombs
Volcanic dust is composed of what?
clay and silt
What can alter climate?
volcanic dust