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Name: Unit III: The –Volcanic Processes Test 2 - KEY Volcanic Processes and Igneous Rocks

Eruption Processes and Types of Volcanoes

1. What is the key ingredient required to make a erupt? large amounts of dissolved gasses in the increase the and lower the density 2. Compare a volcano (A) to a (B):

(A) stratovolcano (B)

Magma Type - very low - high viscosity, very sticky . and Viscosity

Shape and slope Very low slope, broad sides and rounded Slope is much steeper; the top of the of the volcano: top. makes a tall peak.

Describe what a Often produces violent eruptions that are Typical eruptions are somewhat calm, made typical eruption very explosive and produces pyroclasitic of fountains and lava flows. is like. flows and large ash clouds.

Name an example of one Kilauea in Mt. St. Helens in state. somewhere in the world. Magma Types and Viscosity

3. How is viscosity of a substance different than its density? Viscosity is the thickness or ease of pouring/running of a material. Density is how much room the matter takes up compared to its amount of matter. Thick tend to have low densities and visa versa.

4. How does the viscosity of magma affect the way a volcano will erupt? Thick, felsic lava will build up pressure until the volcano explodes. Thinner mafic lava will produce a calmer eruption. 5. Label and define each of the features shown in the diagram to the right- (A and B are liquid, C and D are solid ) A. Magma- molten (melted) rock found under the surface

B. Lava- molten rock found on the surface

C. - igneous rocks made of slowly cooled magma underground.

D. - igneous rocks made of rapidly cooled magma out on the surface. 1 | P a g e Volcanic Processes Test 2 Study Guide

Name: Unit III: The Lithosphere –Volcanic Processes Test 2 - KEY

6. Compare the characteristics of the three magma types based on what you have learned in the lab: Mafic Magma Type: Felsic Intermediate

Darker grey color or Color: Lighter colored Darker colored black and white. Name 2 and Feldspar and and it’s made of: hornblende

Viscosity: High- very thick In the middle Low- very thin

Where oceanic and type: Continental Oceanic continental mix

Density: Lower Middle Higher

Name several rocks , , , and made of this type:

Igneous Rocks and Their Formation

7. What is a rock made of? A mixture of minerals and organic materials

8. What is an ? Rock that formed by the cooling, crystallizing, and hardening of molten rock (magma below the surface or lava on the surface depending on the location)

9. What observable characteristics of an igneous rock allow you to infer its cooling rate? The size of the grains – large cooled slowly and small, glass, or vesicular cooled fast

10. Intermediate rocks are formed at zones forming trenches where compresses and melts on .

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Name: Unit III: The Lithosphere –Volcanic Processes Test 2 - KEY 11. Use this to explain how the cooling rate of magma impacts its observable characteristics:

Location where cooling Type of Texture: Describe its occurred Mineral size Name an example rock: cooling rate. (Intrusive/Extrusive)

Intrusive- deep Coarse: slow cooling large Granite or diorite underground

Fine: rapid cooling small crystals Rhyolite or basalt

Extrusive- at or very close Glassy: very rapid cooling no crystals Obsidian to the surface Vesicular: very rapid cooling no crystals with with dissolved forming Pumice bubbles bubbles in the rock. : -cooling begins Both- starts deep slowly and then finishes quickly both large and small underground and then gets Andesite porphyry crystals erupted to the surface.

12. While walking around a nearby volcano you notice an igneous rock that is a mixture of light and dark grey colored visible crystals. Based on these characteristics, complete the table below with the correct info: What type of volcano Magma Type: Viscosity: Environment: would this rock form? Stratovolcano – trench Intrusive – cooled slowly Intermediate In between where oceanic and inside continental crust meet 13. Describe the viscosity, magma type, and type of volcano if an observed lava flow was fine-grained, dark-colored basalt that was located several kilometers from the cone of a volcano? What type of volcano Magma Type: Viscosity: Environment: would this rock form?

Extrusive – cooled quickly Mafic Thin Shield close to the surface

Hazard and Risk Management of Volcanoes – Case Study 14. What does VEI stand for? Volcano Explosivity Index What is the scale used for? Rates the amount of destruction caused by a volcano

What range does the scale cover? 0 (no to low impact) to 8 (indescribable and global effects)

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Name: Unit III: The Lithosphere –Volcanic Processes Test 2 - KEY 15. What is the difference between a dormant, active, and extinct volcano? Dormant – not currently erupting, but can in the future Active – currently erupting Extinct – erupted in the past but will not erupt again 16. True or False: are a clue that a volcano is about to erupt 17. Name the volcano that erupted in 1980 and caused damage to Washington and State Mt. St. Helens 18. Define the following and on the line, state if they are related to Shield or Stratovolcanoes: Stratovolcano – Charred items that are air born and effect a small area Shield Lava Fountain – A spectacular display of molten rock being sprayed in the air Stratovolcano – Melting snow and mixes with and ash to create rivers Stratovolcano – Large amounts of pressure cause serious movement and destruction of the cone. Shield Lava Flow - Liquid molten rock that easily pours down the side of the volcano during an eruption. Shield – Underground pipe-like structures that carry lava far from vent. Stratovolcano Plume – Huge amounts of pressure cause the eruption to throw ash several miles into Stratovolcano – A mass of very hot gas and rock that rush down the sides of a volcano

Natural 19. Describe how an occurs. Be sure base your thoughts around . Plates are in constant motion and driven by currents in the – Kinetic Energy. That energy is transferred and stored as potential energy when friction causes the plates to stick. Eventually, an old fault will slip or a new one will form, releasing all of the stored energy at once, as Seismic Waves, in the form of kinetic energy. 20. What is the difference between a focus and an epicenter? The focus is the location in the crust where all of the seismic energy is released from. The epicenter is the location on the ’s surface and gives us coordinates and direction of where the center of the earthquake is located. 21. Describe how triangulation is used to locate the epicenter of an earthquake. As a seismic wave radiates from the epicenter, the energy reaches different locations at different times and is recorded on a seismograph. These readings show the arrival of the P and S waves. Knowing the time difference between the arrival of the waves allows us to find the distance the station is from the epicenter, but not the direction. So a circle is draw around three different seismograph cities. Where they intersect is the location of the epicenter – where the fault slipped and the energy radiated from. 22. What is the relationship between the S-P travel time and the distance from the epicenter? The further a city is located from the epicenter, the longer the distance between the P and S Waves. 23. What is the relationship between the S-wave amplitude and the distance from the epicenter? The further a city is located from the epicenter, the lower (less shaking) the amplitude is. 24. What does the Richter scale measure? The amount of energy released from the epicenter. 25. How do you create a ? Displace oceanic crust (underwater) with any type of fault.

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