NATURAL DISASTERS (GLY

Transcription

1 NATURAL DISASTERS (GLY 125: 001, 002) Version #1 Exam # 2 October 11, 2012 Completely Darken the Appropriate Letter on the Scantron that Best Answers the Question (2 pts each) 1. Pahoehoe lava: a. is full of gas holes and is porous (holes) b. looks like coils of rope and has a smooth surface c. has a clinker, angular or jagged top d. always has a rhyolite composition 2. Flows are classified by water content; below, which % water would be classified as a slurry flow: a. 10 b. 30 c. 55 d The angle of repose is: a. the minimum stable angle for unconsolidated material b. the resting angle that occurs during mass extinction of large mammals c. less for angular gravel than fine rounded sand grains d. the angle of entry into Earth s atmosphere of bolides e. the maximum stable angle for unconsolidated material 4. The Hawaiian Island volcanoes are produced by a hot spot; the lava type is a. andesitic b. rhyolitic c. basaltic d. explosive 5. The gravitational force (driving force) that attempts to move material downslope can be decreased by: a. increasing slope angle b. removal of water c. decreasing slope strength d. increasing load 6. Stratovolcanoes or composite volcanoes are composed predominantly of: a. lava flows b. a combination of volcano types c. pyroclastic material d. lava flows and pyroclastic material e. a cinder cones 7. A slide that moves on pre existing curved surfaces of weakness is a: a. rotational slide b. littoral slide c. mudslide d. translational (rock/block) slide e. rock topple 8. Cinder volcanoes have which of the following characteristics: a. classic cone shaped features that have high elevations and are explosive b. small cones less than about 1000 m in height with side slopes about 35 o c. very small domal shaped features often in other volcanic craters d. extremely large features (width and height) with very gentle slopes composed of basalt lava flows 9. Shield volcanoes have very gently sloping sides because: a. their andesite composition produces huge ash flows that spread over a large area b. their basalt flows have low viscosities so the lava flows easily and spreads over great distances c. their andesite composition produces low viscosity lavas that spread over a low slope d. their basalt magmas blow out violently from all of their pent up steam 1

2 10. The stability of a hillslope is improved by. a. increasing pore water pressure b. steepening the slope c. decreasing the weight of hillslope materials d. removing roots and ground plants e. dissolving the cement between soil or rock grains 11. Stratovolcanoes are associated with which type of plate boundary? a. divergent b. transform c. convergent d. intraplate 12. A landslide where the downward movement occurs on a planar surface is called a: a. debris slide b. translational slide c. rockfall d. rotational slide (slump) e. mudflow 13. The least explosive volcanoes are those that have: a. a low magnesium and iron content b. high silica content and high viscosity c. low water content d. low silica and low viscosity 14. The citizens of which of the following towns were able to stop the advance of lava from closing their natural harbor thus preserving their primary source of income? a. Krakatau, Indonesia b. Vestmannaeyjar, Heimaey, Iceland c. Soufriere Hills, Montserrat, West Indies d. Santorini, Greece 15. Santorini in the Aegean Sea underwent an explosive series of eruptions around 1628 BCE that buried the Bronze Age city of Akrotiri on Thera to depths of 70 meters. Many consider this eruption the source of? a. the eruption that covered Pompeii b. the legend of Atlantis c. the initiation of plate convergence in the Mediterranean d. beginning of the collapse of the Roman Empire 16. Examine the diagram to the right of the Pacific NW Coast of the U.S. The triangles represent volcanoes; based on the plate boundary type, illustrated by the saw teeth, what kind of volcanoes occur? a. composite b. shield c. cinder d. domal 17. Examine the diagram to the right of the Pacific Northwest Coast of the U.S. The saw teeth along the line off the coast of northern California, Oregon & Washington is a plate boundary; what type is it? a. transform b. hot spot c. divergent d. convergent 18. What evidence do scientists use to decide whether a stratovolcano may be getting ready to erupt? a. an increase in steam or ash clouds containing shreds of fresh volcanic glass b. numerous micro earthquakes (harmonic tremors) c. a large bulge growing on the flank of the volcano d. an increase in sulfur oxide gas emissions from the volcano e. all of the above 2

3 19. From the following volcanic eruptions, which had (or has if erupting) the highest VEI? a. Kilauea Volcano, Hawaii b. Mt. St Helens volcano c. Krakatau Volcano d. Yellowstone, Wyoming 20. A fluid s resistance to flow is an example of: a. VEI b. density c. viscosity d. resisting force 21. Pyroclastic debris forcefully ejected into the atmosphere as hot particles of various sizes : a. originates as magma b. originates as aa lava c. originates as pahoehoe lava d. are fumaroles 22. Examine the chart on the right; the silica content of basaltic magma is? a. higher than rhyolitic magma b. lower than rhyolitic magma c. the same as rhyolitic magma d. none of the above 23. Examine the chart on the right; the viscosity of rhyolitic magma is? a. higher than the viscosity of basaltic magma b. lower than basaltic magma c. the same as basaltic magma d. none of the above 24. Examine the chart on the right; which magma type has the lowest water content? a. basaltic b. andesitic c. rhyolitic d. there is not difference 25. The slow (< 1cm/year) continuous movement of unsaturated regolith downslope resulting in bent trees, overturned tombstones, etc. illustrated to the right is an example of: a. slide b. topple c. creep d. solifluction e. flow 26. The May 1980 eruption of Mt. St. Helens resulted in huge mudflows racing downslope along the North and South Fork of the Toutle Rivers; these are called: a. lahars b. pyroclastic surges or flow c. debris avalanches d. blow downs 27. From the list of the following locations, where would you expect to see solifluction? a. Mexico b. Italy c. Siberia d. Egypt 28. What is the most abundant gas in magmas: a. water vapor b. carbon dioxide c. carbon monoxide d. methane e. sulfur dioxide 3

4 29. The principal difference between a rock fall and a rock topple is the. a. direction taken by the moving rock downslope b. grain size of the material involved c. former mass contains abundant water whereas the latter is dry d. former mass travels through the air while the latter pivots about a point 30. Which of the following factors increases the risk of mass movement? a. nearby earthquakes b. excavation into the base of a hill c. adding weight to the top of a hill d. allowing water to accumulate in the regolith e. all of the above 31. Two huge calderas, each more than 20 km across characterize Yellowstone National Park; how do such calderas form? a. When a giant volcano erupts, it blows out the surface rocks to leave the giant depressions. b. When a basalt magma gets close to the surface it melts the overlying rocks leaving the depressions. c. A large mass of molten magma flows onto the Earth's surface leaving a void for the rocks above to collapse into. d. Coriolis effects on the near surface magma drag the surface rocks down. 32. Examine the diagram (right) that illustrates the size of the various types of volcanoes; which type is indicated by the letter A: a. cinder b. shield c. composite d. lava dome 33. Examine the diagram (right) that illustrates the size of the various types of volcanoes; which type is indicated by the letter B: a. cinder b. composite c. shield d. lava dome 34. Examine the diagram (right) that illustrates the size of the various types of volcanoes; which type is indicated by the letter C: a. cinder b. composite c. shield d. lava dome 35. Why do highway departments sometimes pile huge boulders near the base of a sloping road cut? a. to prevent gullying of the sloping road cut b. to keep vegetation from growing on the sloping road cut c. to prevent water from getting into the slope d. to prevent slumping of the road cut by loading the toe of the potential slump thus increasing resisting force e. to prevent damage to the road cut from collisions with erratic drivers 36. The angle of repose for dry fine to coarse sand is degrees. a. 10 to 15 b. 30 to 40 c. 40 to 50 d. 75 to 80 e. 20 to Of the following United States, which is NOT susceptible to landslides? a. Florida b. western Colorado c. Appalachian Mountains d. Pennsylvania e. Texas 4

5 38. Ways in which the driving force of material on a slope can be increased include all of the following except: a. removing water b. decreasing slope strength c. increasing slope angle d. increasing slope load 39. When pore space between sand grains is saturated with water, cohesion between the grains is affected because: a. the load of the water increases the friction between the grains b. the load of the water forces the grains apart c. the shear strength of the grains is increased d. there is no affect by water on cohesion e. humans can pump the space for natural gas 40. Examine the hill slope profile to the right and identify the affect below that increasing slope angle has on the relationship between the driving force and resisting force? a. decreases b. variable, as other factors are involved c. increases d. none 41. It is purported that Edvard Munch, probably the most famous Scandinavian painter, was inspired to paint The Scream because of the vibrant twilights in his native Norway caused by the eruption of: a. Vesuvius b. Santorini c. Mt. St Helens d. Krakatau 42. The two most active Cascade volcanoes over the last 4000 years are: a. Mt St. Helens and Mt. Rainier b. Mt. St. Helens and Mt. Shasta c. Mt. Shasta and Mt. Lassen d. Mt. Shasta and Mt. Rainier e. Mt. Mazama (Crater Lake) and Mt. Garibaldi 43. Examine the diagram to the right of the Mt. Rainier, Washington area and notice the colored areas along the Puyallup & White Rivers. These represent past hazard areas associated with former eruptions of Mt. Rainier; what kind of hazards do they represent? a. lava flows b. mudflows c. fumaroles d. caldera rims 44. Volcanic eruptions dominated by basalt compositions are found where? a. along convergent margins involving oceanic and continental crust b. along divergent boundaries at mid oceanic ridges c. over continental hotspots d. between plates along transform boundaries e. none of these 45. What causes a big bulge to slowly grow on the flank of an active Cascades volcano? a. Thick lava flows pile up around the vent. b. Rising magma is pushing it up. c. The magma reacts with snow on the volcano, causing magma inflation. d. The hot magma melts older ash, causing it to expand. 46. Factors used to devise the Volcanic Explosivity Index (VEI) include: a. major eruptions between b. volume of material erupted c. height of volcanic columns d. length of time of the volcanic eruption e. all of the above 5

6 47. The most powerful of all volcanic eruptions erupt after long a dormancy, and occur when viscous high silica magma (Al and K rich) combines with gas resulting in huge ash clouds that shoot high into the atmosphere; these type of eruptions are identified as: a. Icelandic eruptions b. Hawaiian eruptions c. Strombolian eruptions d. Vulcanian eruptions e. Plinian eruptions 48. What can cause water to separate from a water bearing basaltic magma to drive an eruption? a. Injection, into the basalt magma chamber, of dry rhyolite magma from below can cause water to separate. b. Water streaming up into the magma chamber from the Earth s mantle can cause this. c. A decrease in pressure as the magma rises can cause water to separate. d. Once water gets into a basalt magma, it can t separate. e. Basalt magmas only erupt as lava flows; water is irrelevant. 49. What is the best way to avoid a mudflow? a. Run away from it as fast as you can. b. Climb up the valley wall. c. Crawl up into a ball. d. Jump over it. e. Climb a tree. 50. According to the text, which of the following is one of the most hazardous volcanic areas in the world? a. Campi Flegrei b. Mount Vesuvius c. Mount St. Helens d. Mount Hood e. Mount Mazama Tear along line and turn in with the Scantron NAME: Identify your major. Now explain in the space below how you can relate your area to the subject of Natural Disasters. Bonus Question (5 points). 6