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