Download Volcano Review Sheet KEY

Environmental Science
Volcano Review Sheet
1. List and describe the components of the 4 “spheres” of the Earth.
a. Geosphere; rock and soil
b. Atmosphere; air
c. Hydrosphere; water
d. Biosphere; area where organisms live
2. Draw and label a cross section of the Earth based on (1) Chemical Composition and (2)
Physical Composition.
Chemical
Physical
3. What are tectonic plates? A large, mobile slab of crust making up part of the Earth’s
surface.
4. Who developed tectonic plate theory? Alfred Wegener
5. What was the name of the “supercontinent”? Pangaea
6. What is the current theory on how the plates move? Through convection currents.
7. What is a fault? A fracture in the Earth along which movement has taken place.
8. Draw and label a Normal, Reverse, and Strike-Slip fault.
Normal
Reverse
Strike-Slip
9. What are the 2 types of crusts? Which is more dense and why?
Continental and Oceanic. Oceanic is more dense due to the higher concentrations of
minerals.
10. Draw the three types of plate boundaries. Use arrows to indicate movement of the plates.
11. What types of landforms would you find at each boundary?
Convergent: trenches, volcanoes, mountains
Divergent: ridges, mountains
12. What are the 3 types of collisions you can have at a convergent boundary.
Continental to Continental; Continental to Oceanic; Oceanic to Oceanic
13. Draw and explain a subduction zone.
14. Define the following terms:
a. Volcano - A hill or mountain constructed by the extrusion of lava or rock
fragments from a vent.
b. Magma – Molten rock below the surface of the Earth.
c. Lava – Molten rock that reaches the surface of the Earth.
d. Viscosity – Resistance to flow.
15. Name and describe the 3 types of volcanoes.
Shield – gentle, sloping sides; non-explosive; low viscosity lava.
Cinder cone – steep sides constructed of loose rock fragments ejected from a central vent.
Composite (stratovolcano) - Tall, steep sides constructed of alternating layers of
pyroclastics and rock solidified from lava flows; Explosive
16. What determines whether a series of volcanic eruptions builds a shield volcano, a
composite volcano, or a cinder cone? The viscosity and contents of the lava.
17. What determines the viscosity of lava? Silica concentration, dissolved gasses, and water
content.
18. What role do gases play in volcanism? The greater the amount of dissolved gases in lava,
the more fluid the lava. If the lava has a higher viscosity, the gases cannot escape easily
so the eruption will be more explosive. If the lava has a lower viscosity, the gases can
escape easily and the eruption will be non-explosive.
19. List and describe the different types of lava.
A’a – rough, jagged surface. Not as runny as pahoehoe.
Pahoehoe - 2nd most abundant type, smooth, billowy surface; flows tend to be thin an
less viscous.
Blocky – large angular block surface; thick flow and slow moving.
Pillow – Most abundant in volume; found in aquatic environs.
20. What do pillow structures indicate about the environment of volcanism? Aquatic
21. What is VEI and how is it determined? Be able to make calculations based on VEI.
Volcanic Explosive Index. Describes the relative size or magnitude of explosive volcanic
eruptions. It is a 0-to-8 index of increasing explosivity. Each increase in number
represents an increase around a factor of ten. The VEI uses several factors to assign a
number, including volume of erupted pyroclastic material (for example, ashfall,
pyroclastic flows, and other ejecta), height of eruption column, duration in hours, and
qualitative descriptive terms.
22. Explain the factors that determine the explosiveness of a volcano.
Two factors determine the explosivity: (1) the amount of gas in the lava or magma and
(2) how easily the gas can escape to the atmosphere. Viscosity determine the ease with
which gases can escape. The more viscous the lava and the greater the volume of gas, the
more violent the eruption.
23. What are the different destructive forces of volcanoes?
Pyroclastic fall, pyroclastic flow, lava bombs, lahars, debris avalanche, lava, lightening,
famine, fumeraroles, ash clouds, tephra
24. Compare the hazards of lava flows to those of pyroclastic flows.
Pyroclastic flows are mixtures of hot gas and pyroclastic (rock) debris that flow down the
sides of the volcano at speed of over 400 mph. These flows are generally short lived but
account for the most fatalities. Lava erupted from volcanoes flow down the sides but are
not as fast a pyroclastic flows due to the viscosity of the lava. However, the lava flows
may last for days, months, or years.
25. What are some of the benefits of volcanism?
New land formation, fertile soil, recycling of minerals and material, mineral deposits,
cooling of the Earth’s interior.
26. Explain why humans choose to live near volcanoes.
Fertile soil for farming, near water for fishing, transportation, and recreation, natural
beauty
27. How do volcanoes impact economics?
Increase tourism through natural beauty and soil. Eruptions can hurt tourism by halting
transportation to the area and destruction of land and structures. Large ash clouds cause
air travel to stop in the area. This means people cannot get to the destination or leave the
destination. Destruction of farmland impacts food production in the area. Etc…