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20 Cards in this Set
- Front
- Back
What percent of Iceland is covered by glaciers and what percent is covered by active volcanoes?
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13% covered with glaciers and 33% covered with active volcanoes
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Where is volcanism most dangerous?
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At subduction zones
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At subduction zones where does melting take place and what is it aided by?
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Melting is part of the aesthenosphere wedge above the subducting plate and is aided by water released from sediments.
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Melting occurs ______ km below the surface.
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100
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How is the age of an eruption determined?
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Radio carbon dating of trees and mudflows.
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What type of landform is Lassen Peak in California and how did it form?
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It is a lava dome was created when snow melted and the water caused an eruption. It is one of the largest lava domes known.
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When was Mount Shasta's last eruption and what problems do lahars cause?
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1786, lahars are prone to flow through the valley damaging surrounding towns.
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What are some ways a volcano can kill you?
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1) Suffocate
2) Hot particles of flaming ash can burn you 3) Sulfur dioxide makes acid rain 4) Lahars or mud flows can bury you. |
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What is a pyroclastic flow?
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A super hot turbulent cloud of ash, gas and air rolling at you at a high speed.
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How is a pyroclastic flow generated?
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1) Dome collapse
2) Over spilling of a crater rim 3) Directed blast 4) Eruption column |
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Is Mount Mayon at its deadliest when it is erupting most energetically?
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No, the gas hugs the ground and since less energy is fed into the eruption column it begins to collapse.
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Can pyroclastic flow travel down all sides of a volcano simultaneously?
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Yes, this occured at El Chichon, Mexico in 1982, the volcano had a ring shaped base.
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How frequently are the pyroclastic flows at Unzen?
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Extremely frequent, from 1991-1994 alone there were 7,000 flows. With the growing lava dome big chunks fall off and create flows.
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Can a pyroclastic flow travel across a body of water to kill you?
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Yes, the 1883 eruption of Mt. Krackatoa raced across the sea for 40 km burning 2,000 people.
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Can a pyroclastic flow or lava-dome avalanche cause a tsunami?
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Yes, at Krackatoa there were 36,000 fatalaties caused from a tsunami and at Mt. Unzen there were 15,000 fatalities.
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How did the people at Nuee Ardente die?
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Inhaling gas and being burned
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Where did the volcano Nuee Ardente absorb energy from?
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1) the inital blast
2) gravity 3)gas escaping from airborne magma 4) internal turbulence 5) heating of the air |
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How does famine occur as a result of volcanoes?
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1) Gases from the volcano can slow the growth of grasses.
2) Large area of land can be covered by lava. 3)Pyroclastic fallout can devastate crops and burn animals. |
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What are two example of places where famine occured as a result of an eruption?
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Iceland in 1783 and Tambora, Indonesia in 1815
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How dangerous are lave flows in terms of fatality? What place was an exception to this?
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They are not big killers because of their high viscosity. Nyiragongo, Zaire in 2002 had an unsually low viscosity of the lava.
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