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Practice Test – Geology 105, Chapter 8 from The Changing Earth
written and formatted by Joseph Wilkinson
1. Name three types of seismic waves. _______________, _______________, and
_______________.
2. Name three activities by which human beings can cause earthquakes.
3. The mantle constitutes _______________ of the Earth by volume and
_______________ of the Earth by mass (give answers in percentage form).
4. Define the word magnitude in relation to earthquakes. How is earthquake
magnitude recorded?
5. Body waves travel a) around the surface of the Earth, b) through the ocean, c)
through the Earth’s mantle and/or crust, or d) through the Earth’s inner core.
6. Shallow-focus earthquakes originate in the Earth’s _______________;
intermediate- and deep-focus earthquakes originate in the Earth’s
_______________.
7. Earthquakes can/cannot be prevented by human beings. The United States
Geological Survey can/cannot accurately predict earthquakes in advance (circle
correct answers).
8. The asthenosphere is a solid/fluid part of the Earth’s crust/mantle/core (circle
correct answers). It is situated directly above the _______________ and
directly below the _______________.
9. The place where an earthquake originates is called the _______________. The
point on the Earth’s surface directly above this point of origin is called the
_______________.
10. Name two types of surface waves: _______________ and _______________.
11. The Earth’s inner core is solid/liquid (circle correct answer). It has a density of
_______________, and is comprised mainly of the minerals _______________
and _______________.
12. Primary waves (“p-waves”) travel faster/slower (circle correct answer) than
secondary waves (“s-waves”, “shear waves”). Secondary waves start from the
origin a) before primary waves, b) after primary waves, c) at the same time as
primary waves.
13. The word lithosphere refers to the Earth’s _______________ and
_______________. The lithosphere is solid/liquid, and no thicker than
_______________ at its thickest point.
14. Define the word intensity in relation to earthquakes. How is earthquake intensity
recorded?
15. Every interval of one on the Richter Scale represents a _______________
increase in amplitude and a _______________ increase in energy (provide
numerical values).
16. The Earth’s outer core is solid. TRUE/FALSE
17. Most earthquakes are a result of plate tectonics. TRUE/FALSE
18. The oceanic crust is mainly intrusive/extrusive rock rich in the minerals
_______________, _______________, and _______________. The
continental crust is mainly intrusive/extrusive rock rich in the minerals
_______________ and _______________. The oceanic crust is more/less dense
(circle correct answer) than the continental crust.
19. Describe two ways to mitigate earthquake damage to buildings.
ANSWERS:
1. body waves, surface waves, and seismic sea waves (“tsunamis”)
2. deep-well injection of wastes, construction of dams and reservoirs, and
underground nuclear testing.
3. 82%; 67%.
4. The magnitude of an earthquake is a measure of the amount of energy released by
that earthquake. Magnitude is recorded on the Richter Scale (1-10).
5. C: Through the Earth’s mantle and/or crust.
6. crust; mantle.
7. cannot; can.
8. fluid; mantle. situated directly above the lower mantle and directly below the
upper mantle.
9. focus; epicenter.
10. l-waves (“love”/”land” waves) and r-waves (“Rayleigh” waves).
11. solid; 13g/cm3; Nickel (Ni – 6%) and Iron (Fe – 94%).
12. faster; C: At the same time as primary waves.
13. crust and upper mantle. solid; no thicker than 100km.
14. The intensity of an earthquake is a measure of the amount of damage caused by
that earthquake. Intensity is recorded on the Mercalli Scale (I-XII).
15. 10x; 30x.
16. FALSE
17. TRUE
18. extrusive; rich in Silicon (Si), Magnesium (Mg), and Iron (Fe). intrusive; rich in
Silicon (Si) and Aluminum (Al). The oceanic crust (2.9-2.5g/cm3) is more dense than
the continental crust (2-2.9g/cm3).
19. Earthquake damage can be mitigated by avoiding construction in earthquake-prone
areas, and upgrading construction standared (“Richter-Proofing”).