EOSC 114 MIDTERM 2 Last Name, First Name: _____________________________ 2010 Fall - Term 1 Student Number: ____________________ Instructions: Closed book. No calculator. Indicate all your answers on the Scantron sheet. Only the Scantron sheet will be marked, but turn in both the Scantron (answer) sheet and this question packet. Put your name and student number on both the Scantron sheet and the question packet. There is only one best answer to each question. Don’t leave any questions unanswered (if you don’t know the answer, then guess). Good luck! This is “Test Form” (A). Please indicate (A) in the “Test Form” column on your Scantron sheet. 1. The main factor affecting a magma’s viscosity is

A) exsolved gas content B) silica content C) heavy metals content D) dissolved gas content E) oxygen content

2. Which statement is TRUE?

A) Strombolian eruptions typically erupt a greater total volume than Plinian eruptions B) Hawaiian eruptions often measure 3-4 on the VEI scale C) The VEI scale measures the viscosity of erupted magma D) Volcanoes in subduction zones often produce eruptions measuring 5-6 on the VEI scale E) Stratovolcanoes erupt explosively because gas bubbles escape easily from the associated magma

3. What is the main factor controlling whether a specific intermediate composition magma will erupt explosively or

will erupt as a lava dome? A) Magma temperature B) Magma viscosity C) Slope of the volcano D) Magma gas content E) Magma silica content

4. Stratovolcanoes

A) occur at hot spots B) erupt only mafic magma C) always erupt explosively D) occur at divergent margins E) are related to subduction

5. Volcanism at hot spots

A) produces the hottest type of magma B) often results in the generation of pyroclastic flows C) rarely produces lava flows D) produces the most viscous type of magma E) does not produce lahars

6. Which of these statements is FALSE regarding cinder cones?

A) Cinder cones are composed of pyroclastic material B) The construction of cinder cones usually occurs during a single eruption C) Cinder cones erupt intermediate composition magma D) The slopes of cinder cones are usually steeper than those of shield volcanoes E) Cinder cones can occur on the slopes of shield volcanoes

7. How many eruptions of VEI 5 would have to occur in order to accumulate the same volume of erupted material

as one eruption of VEI 8? A) 10 B) 100 C) 1,000 D) 10,000 E) 100,000

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8. Which of the following hazards does NOT occur at shield volcanoes? A) Lahars B) Pyroclastic flows C) Lava flows D) Volcanic bombs E) Fire fountaining

9. The greatest number of fatalities from pyroclastic ash fall usually result from

A) people inhaling ash B) people being buried C) damage to aircraft engines D) roofs collapsing E) accidents due to reduced visibility

10. You live in a town situated in a valley and 60km from an active stratovolcano. Your friend lives in a village

situated on a hill and 10km from the same volcano. Both your town and your friend’s village are situated downwind of the volcano. Which statement is TRUE?

A) The hazard from pyroclastic flows is greater in your town than in your friend’s village B) The hazard from pyroclastic ash fall is smaller in your friend’s village than in your town C) The hazard from toxic gases is greater in your town than in your friend’s village D) The hazard from lava flows is smaller in your friend’s village than in your town E) The hazard from lahars is greater in your town than in your friend’s village

11. The most appropriate technique to monitor a sleeping volcano in a remote, uninhabited area of British Columbia

is: A) Regular sampling of volcanic gases B) Monitoring seismicity in the area C) Measuring the change in slope of the volcano D) Monitoring for a thermal pulse in the area E) Measuring vertical and lateral topography changes

12. Fill in the blanks in the following sentence: Mount Baker is a _______________ that erupts _______________

composition magma and is located at a _______________ margin. A) stratovolcano, intermediate, convergent B) shield volcano, intermediate, convergent C) stratovolcano, basaltic, convergent D) shield volcano, basaltic, divergent E) stratovolcano, felsic, divergent

13. COSPEC and FTIR instruments

A) are used to map volcanic deposits from past eruptions B) record pre-eruption seismicity C) record volcano deformation D) measure the concentration of volcanic gases E) are used to track the movement of volcanic ash clouds

14. Pre-eruption seismicity is caused by

A) tectonic plates shifting B) the volcano deflating C) rocks cracking D) felsic rocks melting E) mantle rocks melting

15. An eruption from Mount Baker could produce the

following hazards to British Columbia A) Lava flows and volcanic ash B) Lava flows and lahars C) Pyroclastic flows and lahars D) Volcanic ash and pyroclastic flows E) Lahars and volcanic ash

16. Which hazard is denoted by the number 2 on the

volcanic hazard map shown to the right? A) Volcanic bombs B) Lava flows C) Pyroclastic flows D) Lahars E) Volcanic ash

17. Landslide fatalities are typically underestimated because: A) many fatalities are associated with the trigger and not the landslide B) most landslides occur in regions where few people live C) they aren’t reported as local governments wish to avoid any charges of negligence and grounds for litigation D) the nature of the injuries sustained do not immediately result in death E) None of the above

18. A community discovering that their homes are built on a slow creeping landslide will need to: A) do nothing, the landslide is too slow and won’t harm people B) remove the offending geology with a large excavation or blasting C) abandon their homes to the slide before they (the people) can be injured D) perform annual maintenance of minor damage E) move their homes further up the slope

19. The shear strength of a slope is always increased by which of the following? A) High clay content. B) High water content. C) High density of fractures. D) Cohesion. E) Adversely angled bedding.

20. Identify in the correct order (from 1 to 4) the types of volcanoes whose silhouettes are shown in the image to the right

A) stratovolcano, shield volcano, cinder cone, caldera

B) cinder cone, caldera, stratovolcano, shield volcano

C) cinder cone, shield volcano, stratovolcano, caldera

D) shield volcano, stratovolcano, cinder cone, caldera

E) cinder cone, shield volcano, caldera, stratovolcano

21. The figure below (and on the screen) shows which type of landslide motion?

A) a complex movement B) a fall. C) a translational slide D) a rotational slide E) a flow

22. Which type of material is involved in the landslide in the figure above? A) Rock B) Soil C) Mud D) Debris E) Earth

23. Which of the following is a landslide “cause” but not a landslide “trigger”? A) Earthquake B) Rapid snowmelt C) A weak clay layer D) Heavy precipitation E) None, all of these are landslide triggers

24. Which of the following are landslide hazard maps NOT used for? A) communicate to city planners and land developers how safe an area is to develop B) plan the alignment of highways, pipelines, etc. through a mountainous valley C) indicate the level of hazard posed by different landslide types D) calculate the factor of safety for a slope E) landslide hazard maps are used for all of the above

25. In the figure below, where arrows represent forces on an unstable rock block on a hill slope, which letter refers to the shear stress? A) A B) B C) C D) D E) E

26. You are a geological engineer retained to mitigate rockfall along new sections of the Sea-to-Sky Highway

(Highway 99 between Whistler and Squamish). You must prevent small blocks of rock from falling onto the road. Which approach to mitigation is the best choice for both public safety and cost? A) avoidance by closing the highway and selecting an alternate route B) protection by installing netting C) protection by installing rock bolts and anchors D) protection by constructing a debris retention structure E) prevention by installing drains

27. While working on the same project described in the question above, but in a different section of highway you are asked to deal with rockslides that may initiate along newly cut rock slopes. To prevent blocks of rock (>1000 m3) from sliding onto the road, which is the best approach to mitigation? A) avoidance by closing the highway and selecting an alternate route B) protection by installing netting C) protection by installing rock bolts and anchors D) protection by constructing a debris retention structure E) prevention by installing drains

28. Compared to wealthier countries, countries in the developing world are likely to have ____ due to landslides? A) higher property damage and lower death counts B) lower property damage and higher death counts C) higher property damage and higher death counts D) lower property damage and lower death counts E) lower property damage and similar death counts

29. Debris flows are common in BC’s coastal mountains because _____. A) of increased population density and land development on steep slopes. B) irrigation for golf courses and farming add significant amounts of water to the ground. C) we are situated in a subduction zone that generates increased earthquake activity. D) of seasonal heavy rains that fall on steep slopes covered by loose sediments. E) frequent volcanic eruptions.

30. For the valley shown in cross section below, the most likely slope failure modes originating from the western (W) and eastern (E) slopes would be _____. A) translational slides (W) and rotational slides (E) B) rockfalls (W) and flows (E) C) translational slides (W) and rockfalls (E) D) rotational slides (W) and translational slides (E) E) rockfalls (W) and translational slides (E)

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