Download Earthquakes and Earth`s interior

Physical Geology Learning Objectives and Study Questions
Chapter 9: Tarbuck and Lutgens, 12 ed.
1. Explain why, in light of the elastic rebound model, that a longer period of repose along a fault
might be expected to produce a larger magnitude earthquake.
2. Distinguish P- and S-waves based on the nature of the particle motions they cause and their relative
speeds and abilities to travel through various Earth materials.
3. Calculate how much the relative amplitudes of ground motion (at a given distance from the
epicenter) and amounts of energy released will differ for two quakes of known magnitudes.
4. Cite two factors that can influence an earthquake's intensity in addition to its magnitude.
5. Describe the measurements you would have to make on a set of at least three seismograms in order
to determine the location of an earthquake's epicenter.
6. Predict which types of earthquake effects (such as building collapse, liquefaction, landslides and
tsunamis) might pose the greatest threats to the populations of large cities, coastal areas or
mountainous areas and explain his or her rationale.
7. Cite one observation that you could make as a basis for a long-term quake prediction, and one that
you could as a basis for a short-term quake prediction. In each case, explain the connection between
what you observe and the potential for an earthquake.
8. Sketch the path a seismic ray will follow if it is reflected from or refracted across a horizontal
boundary between lower and higher density rocks.
9. Briefly explain the physical changes implied by the: (1) decrease in P and S-wave velocities as they
pass through the asthenosphere; (2) increase in P and S-wave velocities in the zone between 400
and 700 km; and (3) "loss" of S-waves as they enter outer core.
10. Sketch a cross-section of the Earth that shows the paths followed by a series of P and S-wave rays
as they traverse the mantle and core. Be sure to label the angular positions of any shadow zone
boundaries defined by the rays.
1. As P-waves pass through a material, particles move _____.
A. perpendicular to the wave motion
B. parallel to the wave motion
C. in circular patterns
D. side to side from the wave motion
E. not at all
2. S-waves cannot pass through Earth’s _____.
A. crust
B. asthenosphere
C. lower mantle
D. outer core
E. inner core
3. The “strength” of an earthquake estimated from how easily it is felt and the damage it does is its
_____.
A. intensity
B. severity
C. magnitude
D. seismicity
E. moment
4. An earthquake with a magnitude (moment magnitude) of 8 releases approximately _____ times as
much energy as a M 5 earthquake.
A. 33
B. 100
C. 1100
D. 10,000
E. 36,000
5. In addition to shaking, earthquakes cause damage by causing _____.
A. landslides
B. tsunamis
C. liquefaction
D. fires
E. all of the above
6. In order to generate a tsunami an earthquake must _____ or trigger an undersea landslide.
A. offset the seafloor laterally
B. cause a volcanic eruption
C. offset the seafloor vertically
D. occur at the same time as a high tide
E. have a magnitude of at least 9
7. Although most earthquakes occur _____, some occur well inland at places like New Madrid,
Missouri.
A. along coastlines
B. along continental margins
C. in mountainous regions
D. along plate boundaries
E. in politically liberal areas
8. Long-range forecasts of earthquakes rely on the measurement of _____.
A. ground deformation
B. foreshocks
C. radon emission
D. groundwater levels
E. recurrence intervals
9. Short-range predictions of earthquakes rely on _____.
A. foreshocks
B. groundwater levels
C. radon emission
D. P-wave velocity
E. all of the above
10. Seismic waves that change direction as they bounce off of boundaries between materials with
different properties are _____.
A. diffracted
B. diffused
C. reflected
D. refracted
E. scattered
11. At depths of about 400 and 700 km, pressure in the mantle causes the minerals in peridotite to
form _____.
A. small amounts of melt
B. rising plumes
C. less dense minerals
D. denser minerals
E. earthquakes
12. S-waves are not received at stations farther than 103° from an earthquake’s hypocenter because of
interaction with the _____.
A. crust
B. lithosphere
C. asthenosphere
D. outer core
E. inner core
13. P-waves are not received at stations between 103 and 143° away from an earthquake’s hypocenter
due to refraction by _____.
A. crust
B. lithosphere
C. asthenosphere
D. outer core
E. inner core