Spring 2005 Test1 (100+ec points)
ISNS 4359 EARTHQUAKES AND VOLCANOES Carefully read each question and select the best
answer by circling the T or F for true or false, filling in the blank, writing a short answer, or by drawing a
picture as instructed.
Your Name__________________________________________
T or F 1. The duration of ground shaking does not affect the numbers of lives lost from earthquakes in
populated areas such as large cities.
T or F 2. In general, there is an inverse correlation between the frequency and the magnitude of disaster
processes such as earthquakes and volcanoes (that is, the largest events occur least frequently).
T or F 3. Only a small fraction of the radiant heat energy generated by the Sun reaches the Earth’s surface,
but it is over a hundred times the average heat flowing from the Earth’s interior to the surface.
T or F 4. Each year, the Earth is shaken by several million earthquakes with Magnitude >1.0, but only less
than an average of twenty with Magnitude >7.0.
T or F 5. The average rate of plate motion is comparable to the rate of human fingernail growth, about 4
cm/yr.
T or F 6. The Earth’s core is mainly composed of silicon, whereas the mantle is composed of magnesium,
nickel, and oxygen.
T or F 7. When data from the Earth’s magnetic field locked inside volcanic rocks on the seafloor became
widely understood in the 1960’s and 1970’s (so-called “magnetic stripes”), skeptics around the world were
convinced that seafloor spreading at mid-ocean ridges occurs, thereby validating concept of plate
tectonics.
T or F 8. The concept of isostasy applies a buoyancy principle to the lower-density continental crust that
‘floats’ on the denser mantle below and is higher because of greater thickness, compared with oceanic
crust.
T or F 9. Most subduction-zone earthquakes on Earth presently occur around the rims of the Arctic and
Indian Oceans.
T or F 10. The fate of oceanic lithospheric plates is destruction resulting from subduction into the mantle.
T or F 11. The primary cause of human deaths in earthquakes in the last century was people being
swallowed alive by the Earth or drowning from resulting tsunami, but not by building collapse.
12. Name the three main types of plate boundaries corresponding to these relative directions of plate
motions (map views).  


A____________________________B____________________________C__________________________
_____13. The oldest oceanic crust rocks on the world’s seafloor are approximately: (a) 50,000 years; (b) one
million years; (c) 200 million years; (d) 2 billion years; or (e) 4.5 billion years old.
_____14. As an observer moves away from an oceanic ridge spreading center, the rocks forming the oceanic
crust: (a) become progressively younger; (b) become progressively older; or (c) do not change
significantly in age.
_____15. The most famous and outspoken of the early proponents of continental drift was: (a) Plato, for
whom "plate tectonics" was named; (b) Leonardo Da Vinci; (c) Alfred Wegener; (d) Galileo;
(e) Immanuel Kant; or (f) Isaac Newton.
_____16. The age of the Earth is approximately: (a) 10 million years; (b) 100 million years;
(c) 1 billion years; (d) 4.6 billion years; (e) 46 billion years or (f) 46 trillion years.
_____17. Compared to the lithosphere, the asthenosphere (a) is weaker, (b) is stronger, or (c) has the same
strength.
_____18. Given the time delay between the arrival of P-waves and S-waves on a seismograph, it is possible
to use a formula to estimate : (a) the distance to the nearest plate boundary, (b) average seismic velocity,
(c) distance to the earthquake hypocenter, (d) thickness of the crust, or (e) depth to the hypocenter.
_____19. The total range of values on the Modified Mercalli Intensity Scale is (please note the use of Roman
numerals): A. I-X, B. I-XII,
C. O-XI,
D. I-XIII,
E. I-MCLXVI, or
F. A-E-I-O-U.
_____20. In a normal dip-slip fault, the hanging wall moves in what direction relative to the footwall?
A. up; B. down; C. horizontally to the right; or D. horizontally to the left.
_____21. The Loma Prieta, California Earthquake of 1989 (which halted the World Series, killed ~63
people, and resulted in over $10 billion in damage) occurred along what type of plate tectonic
boundary?
A. Subduction, B. Left-lateral strike-slip, C. Right-lateral strike-slip, or D. Rift/Spreading.
_____22. A unique measure of an earthquake's size or energy released is called the Earthquake:
A. Hypocenter; B. Focus, C. Intensity, D. Epicenter, E. Magnitude, or F. Rupture.
_____23. Which of the following rock/sediment groups is capable of amplifying seismic waves the most,
increasing ground shaking and the resulting damage to nearby buildings? A. Limestones;
B. Granites; C. Alluvium, Muds, and Silts; D. Metamorphic rocks; or E. Sandstones.
_____24. The currently accepted approximate temperature at the center of the Earth's inner core is
approximately the same as the average surface temperature of the sun, which most scientists accept as: A.
50,000-60,000 C,
B. 5,000-6,000 C; C. 500-600 C; D. 50-60 C, or E. –273 C.
_____25. A measure of the violence of ground shaking based on damage done to human-made structures,
surface changes, and felt reports, which varies with distance and ground conditions is called the Earthquake:
A. Magnitude; B. Hypocenter, C. Epicenter, D. Focus, E. Intensity, or F. Moment.
_____26. An earthquake of Moment Magnitude: A. 5-6, B. 6-7, C. 7-8, or D. 8-9 is called a Great
Earthquake, can cause very serious damage to nearby buildings, and globally occurs on average about once
per year.
_____27. The earthquakes releasing the greatest amount of energy in the world occur: (a) where plates
separate from one another; (b) where plates converge towards one other; (c) where plates slide past one
other; (d) within the interiors of plates over 1000 km from plate boundaries.
_____28. Lines of equal Earthquake Intensity typically plotted as curved contours on maps are called:
A. Intensomers, B. Isotherms, C. Isoseismals, D. Isopleths, or E. Isoclines.
_____29. Which type of seismic wave moves the fastest through solid materials?
A. S-waves,
B. L-waves,
C. Q-waves,
D. P-waves, E. R-waves, or
F. Tsunami.
30. Fill in the main type of fault associated with each of the three main types of plate boundaries and
three types of stress regimes (realizing that any and all faults can occur along a given plate
boundary):
A. Reverse, B. Strike-Slip, C. Normal
Plate Boundary
Stress regime
______ Transform
______ extensional
______ Subduction/Collision Zone
______ shear
______Spreading Center/Rift
______compressional
_____31. The Moho (Mohorovicic discontinuity) is one of the major boundaries within the Earth that separates
the: A. core and mantle, B. mantle and crust, C. inner core and outer core, D. upper crust and lower
crust,
E. crust and atmosphere, or F. hydrosphere and atmosphere.
_____32. The point located at the surface directly above the earthquake focus of fault rupture is called the:
A. Isocenter, B. Hypocenter, C. Millicenter, D. Decicenter, E. Epicenter, or F. Megacenter .
_____33. P-wave Seismic velocity generally increases with increasing depth in the earth, so a plot of P-wave
travel time versus travel distance will produce a: A. Curve, B. Straight line, or C. Triangle.
_____34. The Great Alaska Earthquake of 1964 occurred near the boundary separating the North American
and Pacific plates, which in this region is mainly a: A. Left-Lateral Strike-Slip Fault Zone, B. RightLateral Strike-Slip Fault Zone, C. Oblique-Slip Reverse Fault Zone, or D. Normal Fault Zone.
_____35. Most human deaths associated with the 1906 San Francisco Earthquake were caused by:
A. Building collapse, B. Tsunami, C. Fire,
D. Landslide, or E. None of the Above.
_____36. The two main types of Seismic Surface Waves were named after:
A. Poseidon and Seismos
B. Lasting and Rattling, C. Love and Rayleigh, D. Linear and Righteous, or E. Larry and Roy.
a._______________________________37. What are the two main causes of lithospheric plate motion?
(hint-both involve gravity)
b._______________________________
_____________38. What do most geologists call a fracture in rocks across which offset has occurred?
_____________39. Which type of seismic body wave cannot be transmitted through a liquid or gas.
___________________________40. Name two of the largest 13 plates that lack a major continental
landmass:
41. Fill in the main type of plate boundary that characterizes most of the following six boundaries:
A. Divergent, B. Convergent, C. Strike-Slip or Transform, or D. The plates do not form a boundary
____Arabian-African (Red Sea)
_____ Cocos-North American
____North American-Eurasian (in the Atlantic)
_____ Indian-Antarctic
____North American-Pacific (in California)
_____ Nazca-South America
________________________________42. What is the name of the seismic zone along the Mississippi
River in the central USA in which three M7-8 earthquakes occurred from Dec 1811 to Feb 1812?
lith____ asth____43. How is heat mainly transferred in the lithosphere (lith) & asthenosphere (asth): A.
radiation, B. conduction, C. nuclear fission, D. convection,
E. nuclear fusion,
F. quarks entering
black holes
44. What seismic features do geologists use to distinguish between underground nuclear explosions and
natural tectonic earthquakes?
_____45. Seismic moment of an earthquake is calculated by multiplying all except which one of the
following 3 quantities together? (a) the shear strength (modulus) of the rocks, (b) the Modified
Mercalli Intensity at the epicenter, (c) the rupture area of the fault, or (d) the average displacement (slip)
on the fault.
46. Scientific explanations of natural phenomena are testable and verifiable, whereas Religious
explanations are based on _____________________________________.
47. What are the three main sources of energy that drive natural disasters such as earthquakes, volcanoes,
windstorms, hurricanes, and floods? A._______________ B._________________ C._________________
48. Compare how natural philosophers living 2000 years ago and geoscientists in the last 40 years have
explained the causes of earthquakes and volcanoes.
2000 years ago:
last 40 years:
49-50. Describe in several (3-5) short sentences how the plate tectonic cycle works (you may use map or
cross section sketches to help illustrate the process if you wish). You do not have to define these terms
but may wish to use them in your concise response: lithospheric plates, asthenosphere,
conduction, convection, continental crust, collision, cold, drift, dense, oceanic crust,
subduction zone, hot, rift, seafloor spreading centers.
Extra credit (max 6 points total)
a. Why do a vast majority (>90%) of earthquakes occur along plate boundaries?
b. What is the name of the most common rock on Earth (that is, this green rock forms the Earth’s mantle,
accounting for >80% of the Earth’s volume) and what are the three main elements that compose this
rock?
c. A Magnitude 6.4 earthquake occurred at Zarand in Central Iran at 5:55 AM this morning destroying
over a dozen villages and killing over 230 people. What 2 plates were involved and what type of plate
boundary do they form? Provide a map sketch showing plate motions if you wish.