Earth Science- Volcanic Eruptions Continute
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- 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.
- 100
- 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?
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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. - 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?
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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?
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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?
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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. - 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.