DOC PREVIEW
Montclair EAES 104 - CHAPTER 6 - End of Chapter Answers

This preview shows page 1-2-3-4 out of 12 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 12 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 12 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 12 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 12 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 12 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

CHAPTER 6VOLCANOES: MATERIALS, HAZARDS, AND ERUPTIVE MECHANISMShttp://vulcan.wr.usgs.gov/home.htmlHeliker, C. 1993, Volcanic and seismic hazards on the Island of Hawaii: Bishop Museum Press, Honolulu, 52 p.Heliker, C., D.A. Swanson, and T.J. Takahashi, 2003, The Pu’u O’o’ Kupaianaha eruption of Kilauea Volcano, Hawai’i: The first 20 years: U.S. Geological Survey Professional Paper 1676, 206 p.Sigurdsson, H. 1990, Assessment of the atmospheric impact of volcanic eruptions, in Global catastrophes in Earth History, An interdisciplinary conference on impacts, volcanism, and mass mortality, V.L. Sharpton and P.D. Ward, editors: Geological Society of America Special Paper 247.CHAPTER 6 - End of Chapter Answers1. What factors influence the violence or style of an eruption?* amount of water (more water, more violent eruptions)* viscosity of the magma (higher viscosity, more violent eruptions)(or composition of magma - e.g. rhyolite more violent than basalt)2. What properties of basalt magma control its eruptive behavior?* low water contenta. low viscosity3. What properties of rhyolite magma control its eruptive behavior?* high water content* high viscosity4. What drives an explosive eruption?* steam5. How does pahoehoe lava differ from aa lava?* pahoehoe is ropy-looking; aa is clinkery6. How fast do red hot basalt flows typically move?* less than 1 meter per second (about that of a brisk walk)* about 20 cm* an ash flow. Falling ash is cool or cold. An ash flow would incinerate the person; it is extremely hot and suffocating* The ash gets into the engine and the engine heat melts it. It coats the inside of the engine and can stop it, causing the plane to crash.* It grows because rising magma is pushing it up* The intense lateral blast at the beginning of the eruption blew them all down with their tops pointing away from the site of the blast.* Not safe. Ash flows can cross much wider bodies of water.* an ash-flow tuff is not thinly layered and pumice fragments in it generally become coarser upward. Its lower part is commonly cross-bedded. It forms thicker deposits in valleys and its lower part may show lenses of black obsidian.* mudflows. They flow down valleys where people live. They flow at high speed and are as dense as wet concrete.Chapter 6 - Short answer questions1. About how fast can ash flows travel?* more than 160 km per hour; up to 200 km per hour2. What are the main distinctions between basalt and rhyolite? Complete the following table:basalt rhyoliteb. color: *black or dark white or pale colorsc. silica percent: *50 % 70 %d. most abundant gas: *carbon dioxide water (or steam)e. viscosity (relative): *low highf. how explosive (relative): *not very very3. A basalt magma typically erupts in what form?* lava flows4. A rhyolite magma typically erupts in what form?* ash (ash fall or ash flow)5. What are the two most-abundant gases in magmas?6. Which common volcanic gases are poisonous? Name two.* carbon dioxide in high concentrations* sulfur oxides (or hydrogen sulfide)7. Which of those two gases is heavier than air, collects in low areas, and can asphyxiate people or animals if it is in high concentrations?* carbon dioxide8. What two main influences on a water-bearing basaltic magma can cause water to separate from a magma to drive an eruption?* decrease in pressure* crystallization9. What two main factors dictate that an erupting magma will be explosive?* high water content, high viscosity10. If the bulge grows steep enough it may collapse. Explain how this can trigger an explosive eruption?* Collapse of the bulge decreases pressure on gases dissolved in the magma. That permits them to separate from the magma, expand rapidly, and drive the explosive eruption.11. Sketch a simple diagram to show controls over the hazard distance from a volcano for an ash flow. Label the diagram completely.12. If an ash flow approaches you from the opposite side of a large hill, are you likely to be safe or not? Explain why.13. An extremely large volcano with very gentle slopes is likely to be what kind of volcano and is likely made of what kind of rock? Be specific.* a shield volcano of basalt lava flows14. A large, steep-sided volcano is it likely made of what composition of rock? In what form was the rock erupted? What type of volcano is it?* andesite lava flows and ash; a stratovolcano15. A small, steep, smooth-sided volcano is likely to be what type of volcano? What is it likely made of?* basalt fragments; a cinder cone.16. Why do landslides sometimes trigger explosive eruptions?* Removal of load by landsliding, decreases pressure on gases in the magma and permit them to expand explosively.17. How does lava differ from magma?18. Why might a landslide trigger a volcanic eruption?19. What danger signs might indicate that a volcano may be preparing to erupt?1. What two main factors result in more violent eruptions?a. not too much water and low enough viscosityb. * more water and higher viscosity of the magmac. higher viscosity and narrow enough ventd. strong rocks around the vent and more watere. a large enough volcano with low-viscosity magma.2. What properties of basalt magma control its eruptive behavior?a. low water and large magma volumeb. high water and low magma volume.c. * low water content and low viscosityd. low water and high viscositye. high water and low viscosity3. What properties of rhyolite magma control its eruptive behavior?a. * high water content and high viscosityb. low water and large magma volumec. high water and low magma volume.d. low water content and low viscositye. low water and high viscosity4. How does pahoehoe lava differ from aa lava?a. pahoehoe is full of gas holes and aa is solid lava.b. pahoehoe has a ragged top, aa is smooth on topc. * pahoehoe is ropy-looking; aa is clinkeryd. pahoehoe is rhyolite and aa is basalte. pahoehoe is basalt and aa is andesite5. How fast do red-hot basalt flows typically move?a. about 5 meters per hour.b. about 5 centimeters per minutec. * less than 1 meter per secondd. 10 meters per seconde. 10 kilometers per minutea. no amount of ash would cause collapse; it is too light to be a problem.b. more than about 3 cmc. * more than about 20 cmd. more than 2 meterse. more than 20 metersa. ash coats the surface of the wings making the plane too heavy to flyb. ash covers the windshield of the plane so the pilots can’t see where they are goingc. pieces of ash are rising so fast that they shoot down the planed. *ash gets into the


View Full Document

Montclair EAES 104 - CHAPTER 6 - End of Chapter Answers

Documents in this Course
outline

outline

2 pages

Load more
Download CHAPTER 6 - End of Chapter Answers
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view CHAPTER 6 - End of Chapter Answers and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view CHAPTER 6 - End of Chapter Answers 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?