Practice Quiz 3 Answer Key
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1.
Identify the type of stress indicated in each diagram by selecting the correct
respone. (Stress diagram, Copyright © Prentice Hall, Inc.) For each item
below, place the correct letter in front of the type of stress illustrated.
_____B___compressional stress
____A____tensional (extensional) stress
_____C___ shear stress
4.
5.
After erosion, an anticline will have the ____b______ rocks exposed at the center:
a.
younger
b.
older
Identify the type of fold indicated by selecting the correct response:
For each item below write the letter in front of the structure which labels the
correct part of the image.
__D___overturned fold
__B___symmetrical syncline
___C__asymmetrical anticline
___A__symmetrical anticline
6. Which of the following is NOT a difference between an “anticline” and a
“syncline,” when comparing the two different types of folds?
a. anticlines "open" downward, whereas synclines "open" upward
anticlines have older rocks in their middle (core) zone / synclines have younger
b.
rocks in their middle (core) zone
c. the two types are inverted relative to each other
d. anticlines "open" upward, whereas synclines "open" downward
7.
Identify the type of fault illustrated by selecting the correct response.
___D____
strike-slip fault
B (low angle
thrust fault
Reverse)
___C____
reverse fault
____A___
normal fault
8.
Which of the following is the best explanation of the difference between a
normal and reverse fault? CHECK ALL that are correct.
a.
b.
c.
Normal faults are usually associated with divergent plate boundaries and
tensional stress, whereas reverse faults are usually associated with
convergent plate boundaries and compressional stress.
Reverse faults are left lateral and normal faults are right lateral slip.
Normal faults are defined by the hanging wall block moved up relative to the
footwall block; reverse faults are defined by the hanging wall block moved
down relative to the footwall block.
9.
The deformation of rock layers can result in old rocks lying on top of younger rocks
so that the Law of Superposition does not apply.
a.
True
b.
False
10.
An earthquake’s source of energy is located at the _____________, but the
location at the land surface above that point is called the ______________.
a.
b.
c.
d.
epicenter, focus
focus, epicenter
fault, slip
primary, secondary
11.
Match the following basic earthquake terms with the appropriate description:
__E___ fault creep
__B___
elastic
rebound
A. a tremor or smaller earthquake that occurs after
a main larger earthquake
B. a “snap back” action – the cause of
earthquakes
__A___ aftershock
C. the location on the surface of the earth, above
which the point of rupture occurred
__F___ foreshock
D. the source point from which all earthquake
energy radiates
___G__ fault
E. slow and gradual displacement along a fault,
usually resulting in little earthquake activity
___C__ epicenter
F. a tremor or smaller earthquake that precedes a
main larger earthquake
___D__ focus
G. large fractures in the Earth along which rocks
are moved and/or displaced, causing earthquakes
12.
Which of the following best describes “elastic rebound” theory of
earthquakes?
As an earthquake occurs, the elastically deformed rocks along the fault
a . spring back to their original shape as much as possible
Just after the earthquake occurs, the elastic rocks along the fault spring
b. forward, then backward.
Just before an earthquake occurs, the elastic rocks along the fault spring
c. forward, then backward.
d.
As an earthquake occurs, the plastically deformed rocks along the fault
gently glide back to their original shape as much as possible.
13.
Which of the following is true about P and S waves?
a. P waves are the faster waves that arrive at seismographs first, before S
waves
b. P waves are the secondary waves that push and pull as they travel from the
earthquake focus
c. P waves are the slower waves that arrive at seismographs after S waves
d. P waves and S waves always arrive together as pairs.
14.
Which is correct regarding P and S seismic waves?
S waves travel through solids, but P waves travel through solids and
a.
liquids.
P and S waves travel through liquids, but S waves do not travel through
b.
solids.
P and S waves travel through liquids, but P waves do not travel through
c.
solids.
d. P waves travel through solids, whereas S waves do not.
15.
Using this earthquake travel-time graph, determine the approximate
distance that this station is from the epicenter of an earthquake if the
difference between first P and first S waves arrivals is 5 minutes.
a. 700 miles
b. 1000 miles
c. 1500 miles
d. 2000 miles
Using the chart and calculated distance from the previous question, if the first P
wave arrived at
10:28 am, what time did the earthquake occur?
a. 10:17
b. 10:22
c. 10:34
d. 10:39
16.
Earthquakes occur most frequently associated with ___________.
a. areas of current tectonic plate margins
b. areas of current continental margins
c areas of current tectonic plate interiors
d Volcanic regions
17.
Which of the following are important reasons to study earthquakes?
a. leads to the better understanding of tsunami (tidal waves)
b. leads to a better prevention of property and life casualties
c. leads to a realistic model of the Earth’s interior
d. leads to the development and refinement of the plate tectonic theory
e. all are important
18. ________ have the highest velocities.
a.
b.
c.
primary waves
secondary waves
surface waves
19. The ___________ is a direct measure of the distance from a seismic
receiving station to the focus of a distant earthquake.
a. time interval between the first P and S wave arrivals
b. magnitude of the ground acceleration of surface wave passing a
receiving station
c. time elapsed between the first P wave arrivals from the first and last
aftershocks
d. time interval between the first P wave and the last surface wave
20.
On earthquake distribution maps, the boundaries of the Earth’s tectonic
plates are shown as zones of low seismic activity.
a. true
b. false
21. The mantle transmits P waves but not S waves.
a. true
b. false
22. The ________ of the Earth does not transmit S waves.
a. outer mantle
b. inner crust
c. outer core
d. inner core
23. Identify the type of seismic activity of the following by selecting the correct
area on the map:
I
____D__. shallow earthquakes in
continental transform faults
___B___
Few detectable earthquakes
____A__
shallow focus earthquakes
along a mid-ocean ridge
____C__
deep earthquakes in a
subduction zone
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
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
The Great Rift Valley of East Africa is characterized by __________.
A) mainly reverse faulting as Africa collides with Arabia
B) mainly anticlines and synclines (folding) as Africa collides with Madagascar
C) mainly normal faulting as East Africa begins to rift apart
D) mainly transform faulting along zones connecting the rift with the Red Sea
Which one of the following statements concerning foci and epicenters is correct?
A) The focus is the faulted point on the surface directly above the epicenter.
B) The fault first cracks at the epicenter and breaks through to the surface at the focus.
C) The epicenter is at the surface directly above the focus where the earthquake initiates.
D) The earthquake starts at the focus and the rupture extends down to the epicenter.
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.
__________ have the highest velocities.
A) Primary waves
B) Secondary waves
C) Surface waves
D) Refracted S waves
On a typical seismogram, __________ will show the highest amplitudes.
A) P waves
B) S waves
C) surface waves
D) body waves
Which of the following foundation materials is most stable during earthquake shaking?
A) bedrock
B) unconsolidated moist soil
C) water-saturate
D) sand and mud
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
Energy is stored in rocks adjacent to the site of a future earthquake as __________.
A) elastic strain
B) plastic flow energy
C) thermal energy
D) plastic strain
__________ refers to the tendency for a loosely consolidated foundation material to lose its
internal cohesion and fail mechanically during earthquake shaking.
A) Slip
B) Liquefaction
C) Brittle fracture
D) Strain
Earthquakes result from the sudden release of elastic strain energy previously stored in rocks
surrounding a zone of fault movement.
a
b
true
false
Tsunamis are caused by sudden displacement of large volumes of seawater.
a
b
true
false
Because their energy dissipates rapidly in deep ocean waters, tsunamis seldom pose any danger
to coastal areas far away from the causative earthquake.
a
b
true
false
_________ are thought to be similar in composition to Earth's mantle.
A) Shooting stars
B) Metallic meteorites
C) Cosmic gas clouds
D) Stony meteorites
Which of the following best characterizes how the diameter of Earth's core and the nature of the
outer core were discovered?
A) Crystalline iron was found in lavas erupted from the deepest known hot spots.
B) By analysis of the P-wave and S-wave shadow zones.
C) Because P-wave speeds are higher in the outer core than in the lower mantle.
D) By using the ratio of iron meteorites to stony meteorites to deduce the relative diameters of the
core and mantle.
The __________ is the seismic discontinuity that forms the 660km deep boundary between the
crust and mantle.
A) Moho
B) D” layer
C) lithosphere
D) Inner Core
Continental crust is generally thicker than oceanic crust. TRUE
High rock temperatures enhance plastic deformation and flow in the asthenosphere and inhibit
brittle fracturing needed for earthquakes to occur TRUE
As P waves pass from the mantle into the outer core, velocities drop abruptly.
TRUE
On the blank spaces provided in the illustration below, fill in the names of the layers of Earth's
interior that are labeled.
NOTE: labeling on these layers is ambiguous and a bad question. It would
be more clearly labeled on the test.
a crust b inner core c lower mantle d asthenosphere
Which level indicates the P-wave shadow zone? (a) __B________
Which level indicates the zone where no direct P-waves are received? (b) ___A_______ (P is
refracted therefore not direct)
Which level indicates the zone where direct P-waves are received? (c) ___C_______
The east coast of North America is a good example of a(n) __________ tectonic margin.
a
passive
b
active
c
transform
d
volcanic