ENV151 EXAM #2

5. ____________ magma is the most abundant type of erupted at oceanic spreading centers. a. Basaltic b. Granitic c. Andesitic d. Pegmatitic

a. Basaltic

23. ____________ tend to increase the explosive potential of a magma body beneath a volcano. a. High viscosity and dissolved gas b. High viscosity; low dissolved gas content c. Low silica content, low viscosity d. Low viscosity; low dissolved gas content

a. High viscosity and dissolved gas

4. ____________ have the highest velocities. a. Primary waves b. Secondary waves c. Surface waves d. Refracted S waves

a. Primary waves

1. The elastic rebound theory for the origin of earthquakes was first proposed by ____________ following the ____________ earthquake. a. Reid; 1906, San Francisco b. Giuseppe; 1925, Pizza Lake c. Richter; 1989, Loma Prieta d. Mohorovicic; 1964, Anchorage

a. Reid; 1906, San Francisco

3. ____________ is a major dissolved volatile constituent in both magmas and volcanic gases? a. Water b. Carbon monoxide c. Hydrogen chloride d. Methane

a. Water

11. ____________ is the maximum possible damage designation on the Mercalli scale. a. XII b. 12 c. X d. 10

a. XII

38. A transform fault is ____________. a. a strike-slip fault that forms the boundary between tectonic plates b. a dip-slip fault connecting an anticline with a syncline c. a reverse fault that steepens into a thrust fault d. the rift bounding faults on a mid-ocean ridge

a. a strike-slip fault that forms the boundary between tectonic plates

8. Major earthquakes are often followed by somewhat smaller events known as __________. a. aftershocks b. foreshocks c. tremors d. hyposhocks

a. aftershocks

41. A horst is ____________. a. an uplifted block bounded by two normal faults b. a downdropped block bounded by two reverse faults c. an uplifted block bounded by two reverse faults d. a downdropped block bounded by two normal faults

a. an uplifted block bounded by two normal faults

28. The average composition of the oceanic crust is thought to approximate that of __________. a. granite b. basalt c. peridotite d. iron

b. basalt

28. Spreading center volcanism most generally produces rocks which are __________. a. granitic in composition b. basaltic in composition c. basaltic in composition d. ultramafic in composition

b. basaltic in composition

15. Paricutin is an example of a __________. a. shield volcano b. cinder cone c. lava dome d. composite volcano

b. cinder cone

large, fairly steep-sided cones composed of lavas and pyroclastic layers

b. composite/stratovolcanoes

the volcanoes of southwestern Alaska and the Aleutian Islands

b. composite/stratovolcanoes

19. The Richter magnitude of an earthquake is determined from the __________. a. duration of the earthquake b. intensity of the earthquake c. arrival time of P and S waves d. amplitude of the surface waves

c. arrival time of P and S waves

22. Which statement about the May, 1980, eruption of Mount St. Helens is false? a. during the eruptive period, the mountain peak was substantially built up by new lava flows and pyroclastic debris b. plumes of ash rose high into the atmosphere during the major eruptive events c. mudflows accompanied the major eruptive events d. the most powerful explosive event was preceded by a massive landslide

a. during the eruptive period, the mountain peak was substantially built up by new lava flows and pyroclastic debris

13. The mechanism by which rocks store and eventually release energy in the form of an earthquake is termed __________. a. elastic rebound b. seismic rebound c. fault displacement d. stress fracture

a. elastic rebound

12. The position on Earth's surface directly above the earthquake source is called the __________. a. epicenter b. inertial point c. focus d. seismic zone

a. epicenter

49. The Sierra Nevada, CA, and Teton, WY ranges are examples of ____________. a. fault blocks uplifted by late Tertiary to Quaternary normal faulting b. folding, compression, and thickening of Paleozoic strata in Jurassic time c. isostatic uplift of crust overthickened in early Paleozoic time d. uplifted blocks bounded by Quaternary reverse faults

a. fault blocks uplifted by late Tertiary to Quaternary normal faulting

29. The average composition of the continental crust most closely approximates that of __________. a. granite b. basalt c. peridotite d. iron

a. granite

54. Folded limestones that occur high in the Himalayas were originally deposited as sediments in a ____________. a. marine basin between India and Eurasia b. Cenozoic fault basin between Africa and Arabia c. deep ocean trench along the southern margin of India d. late Paleozoic syncline north of the Tibetan Plateau

a. marine basin between India and Eurasia

45. Which one of the following shows the correct order (left to right) of decreasing magma viscosity? a. rhyolite, andesite, basalt b. andesite, rhyolite, basalt c. basalt, rhyolite, andesite d. basalt, andesite, rhyolite

a. rhyolite, andesite, basalt

13. Kilauea is an example of a __________. a. shield volcano b. cinder cone c. lava dome d. volcanic neck

a. shield volcano

massive, gently sloping volcanoes built of successive, basaltic lava flows

a. shield volcanoes

the big volcanoes of Hawaii

a. shield volcanoes

12. The Columbia Plateau in the northwestern United States is an excellent example of __________. a. silica-rich lava flows b. pyroclastic flow deposits c. flood basalts d. an eroded shield volcano

a. silica-rich lava flows

22. A ____________ refers to the tendency for a foundation material to lose its internal cohesion and fail mechanically during earthquake shaking. a. Slurrying b. Liquefaction c. Motion slip d. Seismoflowage

b. Liquefaction

47. The ____________ in California is the boundary between the North American and Pacific plates. a. Sierra Nevada frontal fault b. San Andreas strike-slip fault c. San Luis Obispo thrust fault d. San Francisco normal fault

b. San Andreas strike-slip fault

21. The ____________ earthquake was accompanied by extensive fire damage. a. Anchorage, 1964 b. San Francisco, 1906 c. Mexico City, 1985 d. Yerevan, Armenia, 1988

b. San Francisco, 1906

40. A thrust fault is best described as ____________. a. a steeply inclined, oblique-slip fault b. a low-angle, reverse fault c. a vertical, normal fault d. a near vertical, strike-slip fault

b. a low-angle, reverse fault

27. The lithosphere is defined as __________. a. a rocky layer having a relatively uniform chemical composition b. a rigid layer of crustal and mantle material c. a rocky layer composed mainly of crustal rocks d. a plastic layer composed mainly of mantle material

b. a rigid layer of crustal and mantle material

33. Mount St. Helens is ____________. a. a basaltic cinder cone b. an explosive stratovolcano c. a basaltic shield volcano d. a small, welded tuff cone

b. an explosive stratovolcano

16. P waves ____________. a. propagate only in solids b. are faster than S waves and surface waves c. have higher amplitudes than do S waves d. produce the strongest ground shaking

b. are faster than S waves and surface waves

31. The asthenosphere is located __________. a. within the crust b. in the upper mantle c. between the mantle and outer core d. within the outer core

b. in the upper mantle

33. In a ____________ fault, the hanging wall block move up with respect to the footwall block. a. normal b. inverse c. reverse d. abnormal

b. inverse

52. The term ____________ refers specifically to geologic mountain building. a. orogneisses b. orogenesis c. orthogeny d. orthogonal

b. orogenesis

41. Which one of the following best describes volcanism in the Cascade Range, northwestern U. S.? a. related to a mantle hot spot b. related to plate subduction c. related to a mid-oceanic ridge system d. related to deep, transform faults

b. related to plate subduction

23. The record of an earthquake obtained from a seismic instrument is a(n) __________. a. seismograph b. seismogram c. time-travel graph d. epigraph

b. seismogram

31. Which kind of volcanism is typical of mid-oceanic ridge systems? a. explosive; composite cones b. submarine; basaltic lava flows c. fissure eruptions; flood basalts fields d. explosive; rhyolitic, pyroclastic flows

b. submarine; basaltic lava flows

34. In thrust faulting, ____________. a. grabens develop on the footwall block b. the crust is shortened and thickened c. horizontal, tensional stresses drive the deformation d. the hanging wall block slips downward along the thrust fault

b. the crust is shortened and thickened

9. Which of the following is associated with deep mantle hot spots? a. Vesuvius and the other volcanoes of Italy b. the volcanoes of Hawaii and Quaternary activity in Yellowstone National Park c. the very young cinder cones scattered across the southwestern United States d. Mt. St. Helens and other volcanoes of the Cascade Mountains

b. the volcanoes of Hawaii and Quaternary activity in Yellowstone National Park

51. The ____________ are a geologically old mountain range folded and deformed during the Paleozoic. a. Cascades in the northwestern United States b. Rockies in the western United States c. Appalachians in the eastern United States d. Alps in Europe

c. Appalachians in the eastern United States

17. The Mercalli Scale is a scale from ____________. a. 1 to 12 that rates the energy required for faulting to occur b. 1 to 10 that rates the energy released by an earthquake c. I to XII that rates the structural damage due to an earthquake d. I to X that rates the total energy released during the main quake and all aftershocks

c. I to XII that rates the structural damage due to an earthquake

7. The ___________ ocean basin is rimmed by the most subduction zones. a. Atlantic b. Indian c. Pacific d. Arctic

c. Pacific

3. Which one of the following statements is correct? a. P waves travel through solids; S waves do not. b. P and S waves travel through liquids, but P waves do not travel through solids. c. S waves travel through solids and P waves travel through liquids. d. P and S waves travel through liquids, but S waves do not travel through solids.

c. S waves travel through solids and P waves travel through liquids.

42. A syncline is ____________. a. a fold in which the strata dip away from the axis b. a fold with only one limb c. a fold in which the strata dip toward the axis d. a fold characterized by recumbent limbs

c. a fold in which the strata dip toward the axis

35. A graben is characterized by ____________. a. a hanging wall block that has moved up between two reverse faults b. a footwall block that has moved up between two normal faults c. a hanging wall block that has moved down between two normal faults d. a footwall block that has moved down between two reverse faults

c. a hanging wall block that has moved down between two normal faults

48. A(n) ____________ is a thick accumulation of sediments and small, tectonic blocks formed of material scraped off a descending, lithospheric plate. a. mass movement complex b. continental shelf, terrain complex c. accretionary-wedge complex d. subterranean-accumulation complex

c. accretionary-wedge complex

35. The average composition of rocks comprising a large composite cone or stratovolcano is similar to a (an) ____________magma. a. basaltic b. ultramafic c. andesitic d. rhyolitic

c. andesitic

4. Volcanic bombs originate ____________. a. as laser-guided, granite blocks launched from a supersonic jet b. as blocks of volcanic rock ejected from an erupting volcanic crater c. as erupted magma blobs that partly congeal before falling to the ground d. as ash particles that join together in the eruptive plume and fall as cobble-sized objects

c. as erupted magma blobs that partly congeal before falling to the ground

32. Kilauea and Mauna Loa are ____________. a. explosive, rhyolitic volcanoes b. andesitic stratovolcanoes c. basaltic shield volcanoes d. small, basaltic cinder cones

c. basaltic shield volcanoes

44. Large circular downwarped structures are called __________. a. anticlines b. synclines c. basins d. domes

c. basins

Which of the following is NOT considered pyroclastic debris? a. ash b. cinders c. bombs d. pahoehoe

c. bombs

25. Which one of the following statements concerning volcanic blocks and bombs is true? a. blocks are broken fragments of solid rocks; bombs have smaller sizes than lapilli b. bombs are guided to Earth by laser beams; blocks fall anywhere c. bombs are ejected as magma lumps; blocks are ejected as solid fragments d. bombs and blocks are both smaller than lapilli and cinders

c. bombs are ejected as magma lumps; blocks are ejected as solid fragments

34. The 1943 eruption of Paricutin in Mexico was characterized by ____________. a. mudflows and explosive ash eruptions b. welded-tuff deposition and caldera formation c. cinder cone building and basaltic lava d. pyroclastic eruptions and nueé ardente flows

c. cinder cone building and basaltic lava

small basaltic cones built during one, short, eruptive episode

c. cinder cones

39. Brittle deformation would be favored over plastic deformation in which of the following conditions? a. high confining pressures b. warmer temperatures c. cooler temperatures d. shallow depths

c. cooler temperatures

29. Which kind of eruptive activity is most likely to be highly explosive? a. lava flows from a large shield volcano on an oceanic island b. fissure eruptions feeding lava to flood basalt accumulations c. eruptions of big, continental margin, composite cones or stratovolcanoes d. lava flows from a large cinder cone complex

c. eruptions of big, continental margin, composite cones or stratovolcanoes

2. When an earthquake occurs, energy radiates in all directions from its source. The source is also referred to as the __________. a. inertial point b. epicenter c. focus d. seismic zone

c. focus

26. The dense core of Earth is thought to consist predominantly of __________. a. nickel b. lead c iron d. copper

c. iron

46. Tensional forces normally cause which one of the following? a. strike-slip faults b. reverse faults c. normal faults d. thrust faults

c. normal faults

25. Which one of the following statements about the crust is NOT true? a. it is the thinnest of the major subdivisions b. it is thickest where prominent mountains exist c. oceanic crust is enriched in potassium, sodium, and silicon d. continental rocks are compositionally different than oceanic rocks

c. oceanic crust is enriched in potassium, sodium, and silicon

Which type of basaltic lava flow has a fairly smooth, unfragmented, ropy surface? a. aa b. pegmatitic c. pahoehoe d. scoria

c. pahoehoe

24. Most of our knowledge about Earth's interior comes from __________. a. drill holes b. volcanic eruptions c. seismic waves d. examination of deep mine shafts

c. seismic waves

10. The instrument which records earthquake events is termed a __________. a. polygraph b. thermograph c. seismograph d. barograph

c. seismograph

46. The largest igneous intrusive body is called a(n) _________. a. batholith b. laccolith c. stock d. dike

c. stock

32. A ____________ fault has little or no vertical movements of the two blocks. a. stick slip b. oblique slip c. strike slip d. dip slip

c. strike slip

14. Overall, this type of seismic wave is the most destructive. a. P wave b. S wave c. surface wave d. tsunami

c. surface wave

7. On a typical seismogram, ____________ will show the highest amplitudes. a. P waves b. S waves c. surface waves d. body waves

c. surface waves

36. The mountains and valleys of the Basin and Range Province of western United States formed in response to ____________. a. strike-slip faulting and hanging wall block uplifts b. reverse faults and large displacement, thrust faulting c. tensional stresses and normal-fault movements d. normal faulting and horizontal compression

c. tensional stresses and normal-fault movements

27. Which one of the following statements concerning cinder cones is false? a. they are small volcanoes with fairly steep sides b. they are built mostly or entirely during one eruptive cycle c. the cinders and other pyroclastic particles are consolidated into welded tuff d. the cinders most commonly are basaltic

c. the cinders and other pyroclastic particles are consolidated into welded tuff

37. Which of the following best describes Shiprock, a famous volcanic feature in New Mexico? a. a very recently active, basaltic cinder cone b. an extinct, highly symmetrical, composite volcanic cone c. the eroded remains of a volcanic pipe and radiating dikes d. an extinct, massive, rhyolitic shield volcano

c. the eroded remains of a volcanic pipe and radiating dikes

37. In a normal fault ____________. a. the hanging wall block below an inclined fault plane moves downward relative to the other block b. the footwall block below an inclined fault plane moves downward relative to the other block c. the hanging wall block above an inclined fault plane moves downward relative to the other block d. the footwall block above an inclined fault plane moves upward relative to the other block

c. the hanging wall block above an inclined fault plane moves downward relative to the other block

8. Which of the following factors help determine whether a volcanic eruption will be violent or relatively quiescent? a. amount of dissolved gas in the magma b. temperature of the magma c. composition of the magma d. all of these

d. all of these

20. Which one of the following best characterizes tsunamis? a. they cause the land to ripple and oscillate b. they are faster than seismic surface waves c. they have relatively small amplitudes compared to their very long wavelengths d. they are easily seen at sea but are lost in the swell and breaking waves along a coast

c. they have relatively small amplitudes compared to their very long wavelengths

40. The Icelandic volcanoes are related to plate tectonics because ____________. a. they lie on a spreading center where two plates are converging b. they lie on a subduction zone where two plates are converging c. they lie on a spreading center where two plates are moving apart d. they lie along a subduction zone where two plates are diverging

c. they lie on a spreading center where two plates are moving apart

30. The Earth's magnetic field originates by ___________. a. weak electrical currents associated with hot, rising, mantle plumes b. magnetic mineral grains in the inner core c. weak electrical currents associated with fluid motions in the outer core d. magnetization of oxygen and nitrogen atoms in the atmospheric ozone layer by solar radiation

c. weak electrical currents associated with fluid motions in the outer core

53. The ____________ is (are) characterized by terrane accretion that has been active throughout most of Mesozoic and Cenozoic time. a. western margin of Africa b. southern margins of India and Australia c. western margin of North America d. western margin of the Mid-Atlantic Ridge

c. western margin of North America

15. Approximately how much more energy is released in a 6.5 Richter magnitude earthquake than in one with magnitude 5.5? a. 3000 times b. 3 times c. 300 times d. 30 times

d. 30 times

26. ____________ destroyed the city of St. Pierre, Martinique in 1902. a. Mudflows b. Basaltic lava flows c. Heavy ashfall d. A nueé ardente

d. A nueé ardente

In 1980, _____________ was the first Cascade Range volcano to erupt since Mt. Lassen in 1915-16. a. Mt. Rainier b. Mt. Shasta c. Kilauea d. Mt. St. Helens

d. Mt. St. Helens

9. The ____________ magnitude scale is a measure of the energy released. It does not directly measure the extent of building damage. a. Gutenberg b. Reid c. Mercalli d. Richter

d. Richter

14. ____________ are usually the most abundant gases emitted during basaltic volcanism. a. Chlorine and sodium b. Neon and ammonia c. Oxygen and nitrogen d. Water and carbon dioxide

d. Water and carbon dioxide

24. Which type of basaltic lava flow has its surface covered with sharp-edged, angular blocks and rubble? a. scoria b. pahoehoe c. pillow lava d. aa

d. aa

10. Cinder cones __________. a. have very steep slopes b. are usually less than 300 meters (1000 feet) high c. consist largely of pyroclastics d. all of these

d. all of these

6. The amount of destruction caused by earthquake vibrations is affected by __________. a. design of structures b. intensity and duration of the vibrations c. nature of the surface material d. all of these

d. all of these

42. Which of the following statements best describes the big Hawaiian volcanoes? a. lie directly above a transform plate boundary that cuts deeply into the mantle b. lie directly above an active subduction zone where the Pacific plate is sinking into the mantle c. lie along the crest of the East Pacific Rise, a mid-ocean ridge or spreading center d. are situated in the interior of a large, Pacific plate above a hot spot deep in the mantle

d. are situated in the interior of a large, Pacific plate above a hot spot deep in the mantle

18. The distance between a seismological recording station and the earthquake source is determined from the __________. a. earthquake magnitude b. intensity of the earthquake c. length of the seismic record d. arrival times of P and S waves

d. arrival times of P and S waves

44. What volcanic events formed Crater Lake, OR? When did they take place? a. a powerful explosion blew away the top of a stratovolcano; 10 million years ago b. the crater of a large, extinct cinder cone filled with water; 5 million years ago c. landslides and volcanic mudflows dammed the Mazama River; 500 years ago d. caldera collapse followed major ash and pyroclastic-flow eruptions; 6000 years ago

d. caldera collapse followed major ash and pyroclastic-flow eruptions; 6000 years ago

11. The most violent volcanic activity is associated with __________. a. fissure eruptions b. shield volcanoes c. cinder cones d. composite cones

d. composite cones

16. Mount Pelée on Martinique is an example of a __________. a. shield volcano b. cinder cone c. lava dome d. composite volcano

d. composite volcano

43. The Black Hills of South Dakota are a good example of a(n) __________. a. anticline b. syncline c. basin d. dome

d. dome

50. A good example of a present-day, passive, continental margin is the ____________. a. north flank of the East Pacific Rise b. west coast of South America c. east coast of the Japanese Islands d. east coast of North America

d. east coast of North America

45. Which of the following combinations should favor folding rather than faulting? a. high temperature and low confining pressure b. low confining pressure and low temperature c. high confining pressure and low temperature d. high temperature and high confining pressure

d. high temperature and high confining pressure

39. The recent (geologically) volcanic activity in Yellowstone National Park is ____________. a. related to plate subduction b. related to a divergent plate boundary c. related to a transform plate boundary d. related to intraplate, hot spot volcanism

d. related to intraplate, hot spot volcanism

30. Magma tends to rise toward Earth's surface principally because a. water is an abundant constituent of magma b. silica is abundant in magma c. magma is a fluid d. rocks become less dense when they melt

d. rocks become less dense when they melt

36. A ____________ volcano is a very large, gently sloping mound composed mainly of basaltic lava flows. a. composite b. stratospheric c. cinder cone d. shield

d. shield

6. The 1991 Pinatubo eruption in the Philippines caused brilliantly colored sunrises and sunsets to be seen for the next few years. What caused this phenomenon? a. the eruption added large amounts of carbon dioxide to the atmosphere b. the eruptive cloud destroyed parts of the Earth's protective ozone layer c. radioactive atoms blown into the atmosphere glowed red as they decayed d. sulfur dioxide and other erupted gases formed aerosols in the stratosphere

d. sulfur dioxide and other erupted gases formed aerosols in the stratosphere

38. Which region has the greatest concentration of currently active volcanoes? a. the coastal plain of western Africa b. European Russia and Siberia c. the area surrounding the Red Sea d. the circum-Pacific area

d. the circum-Pacific area

5. Which one of the following is true regarding tsunamis? a. they travel as deep-water waves at speeds greater than surface seismic waves but slower than S waves b. their wave heights decrease and wavelengths increase as they move into shallower water c. they are started by fault-induced, horizontal shifts in the sea floor that suddenly propel great masses of water in opposite directions d. they occur in the open ocean, wavelengths are many miles or kilometers and wave heights are only a few feet

d. they occur in the open ocean, wavelengths are many miles or kilometers and wave heights are only a few feet