Geology homework questions
Which of the following is true of the lithosphere?
It is composed of the crust and the uppermost rigid part of the mantle.
Slab pull occurs because subducting slabs are _________, and therefore are _________ dense than the surrounding asthenosphere.
cooler; more
Normal, reverse, and thrust are all examples of ________ faults.
dip-slip
Which basic type of plate boundary is shown in the image below?
divergent
Designing and retrofitting a building to withstand the effects of earthquakes is a type of
earthquake engineering
The distribution of _________ around the globe provides the primary indicator of the boundaries between lithospheric plates.
earthquakes
At transform plate boundaries
earthquakes are common but volcanoes are absent.
We can describe the orientation of planar features such as faults and joints using measurement of the _______.
strike and dip
The deepest earthquakes on earth occur along
subduction zones
Earthquake waves that travel along the Earth's surface are termed
surface waves
What type of seismic waves cause the most damage?
surface waves
produce most of the damage to buildings during earthquakes.
surface waves
In the image below, the rocks have been bent into an elongate trough. This is a(n) ________.
syncline
Oceanic lithosphere thickens as it moves away from mid-ocean ridges primarily because of
the addition of new lithospheric mantle as a result of cooling.
In plate tectonics, a triple junction is a place on the Earth's surface where
the boundaries of three lithospheric plates meet at a single point.
The map below depicts the locations of earthquakes in the ocean basins. Which of the following locations is most likely to be located along a plate boundary?
the middle of the north Atlantic Ocean, where there is a north-south belt of earthquakes
A long delay between the arrival of P-waves and S-waves at a seismometer means that
the seismometer is located far from the earthquake.
The time it takes for a seismic wave to travel from the focus of an earthquake to a seismometer is called the ________.
travel time
Mid-ocean ridges are
underwater volcanic mountain ranges.
Tsunamis are most commonly generated by sudden _________ movement of the seafloor during an earthquake.
vertical
Deep-sea trenches are likely to be located near
volcanic arcs.
Earthquakes that occur in a band called the ________ can be used to track the motion of subducted oceanic lithosphere.
wadati-benioff zone
Seismic retrofitting is the process of
strengthening existing buildings and structures
Lithospheric plates move relative to other along plate boundaries at velocities between ___________
1 and 20 centimeters per year
A magnitude 7.0 earthquake is approximately _________ times larger than a magnitude 5.0 earthquake in terms of ground motion.
100
What is the largest earthquake ever measured?
1960 Chilean Earthquake
According to the moment magnitude scale (Mw), the amplitude of ground shaking during a magnitude 8 earthquake would be 1,000 times greater than a magnitude ________ earthquake.
5
Who proposed continental drift?
Alfred Wegener
_________ proposed the continental-drift hypothesis, suggesting that the arrangement of continents on the planet has changed over geologic time.
Alfred Wegener
Which of the following is NOT an earthquake hazard? A. fire B. tsunami C. flooding D. ground shaking
C. Flooding
Which of the following is true of continental lithosphere compared to oceanic lithosphere?
Continental lithosphere is thicker than oceanic lithosphere.
A good scientific theory... A.is the simplest explanation B. explains a wide range of phenomena C. Begins as a hypothesis D. All of these
D
Which U.S. State has the smallest seismic hazard?
Florida
Match the letter in the seismogram below with the correct seismic wave name:
Group A: P-waves; Group B: S-waves; Group C: Surface Waves
__________ is the balance between the weight of a mountain range and the buoyancy provided by the underlying mantle.
Isostasy
Which of these properly illustrates the principle of isostasy?
Mountains stand high because they are gravitationally balanced by their deep crustal roots.
Which seismic phase travels the fastest?
P wave
Which of the following phases passes through the outer core?
PKP
In earthquake hazard maps, PGA stands for...
Peak Ground Acceleration
In the following graph, why does the line for S-waves NOT appear in the outer core?
S-waves can't travel through the outer core because it is liquid.
Which of the following best describes how scientists study the interior of the Earth?
Scientists use seismic waves, gravity, and magnetism to study the Earth's interior.
What kind of stress is associated with the left lateral strike slip fault?
Shear
How is stress different from strain?
Strain is the change in shape of a rock due to applied stress.
How is stress different from force?
Stress is the force applied per unit area
In a hot-spot volcanic island chain, such as the Hawaiian Islands, which of the following is true?
The ages and distance between volcanoes can be used to calculate plate velocities.
What can be said about the ocean sediments collected from far from the mid-ocean ridge as compared to close to mid ocean ridge
They are thicker and older.
Which of the following best describes the distribution of earthquakes around the globe?
They occur in distinct zones.
a tsunami is
a seawave generated by an earthquake, landslide, or submarine volcanic eruption that may destroy coastal cities thousands of kilometers from its source.
Faults that have moved recently or are likely to move in the future are referred to as ________ faults.
active
The vast majority of earthquakes occur
along any plate boundary
Seafloor spreading is driven by volcanic activity
along mid-ocean ridges.
In the image below, the rocks have been bent into an elongate arch. This is an example of a(n) ________.
anticline
The majority of new oceanic crust is created
at mid-ocean ridges.
Most of the pulling force driving plate motion is produced
at subduction zones.
The rock produced at mid-ocean ridges consists of
basalt at shallow depths and gabbro at deeper depths.
On a geologic map, if the contacts between sedimentary rock units form a bull's-eye pattern of concentric circles, with the youngest unit in the center, the underlying structure is a(n) ________.
basin
The graph below shows the change in velocity of seismic waves with depth in the crust. Why does the velocity of the P-wave drop drastically at the core-mantle boundary?
because the outer core is liquid and seismic waves travel slower in liquids
Short-term predictions of earthquake behavior have
been largely unreliable
body waves include
both S- and P-waves
Faulting and earthquakes are examples of what type of deformation?
brittle
Continental lithosphere does not subduct because it is too
buoyant.
Mountain ranges formed along subduction zones are formed, in part, by ___________ in the crust.
compression
As shown in the figure below, a coiled spring would be useful in illustrating any ________ wave.
compressional
Large, thick-crusted, nonvolcanic mountain belts, like the Himalayas, are associated with
continent-continent collisions.
A ________ is a linear feature in continental lithosphere where a plate is pulled apart, resulting in a deep valley, extensive faulting and volcanism, and if sustained, division into two plates separated by new oceanic lithosphere.
continental rift
Subduction zones are found at _________ plate boundaries.
convergent
What kind of plate boundary is a subduction zone?
convergent
Most medium- and deep-focus earthquakes occur at
convergent plate boundaries
Before an earthquake, rocks can respond to applied stress to a small degree by bending and warping without breaking. This is termed _________.
elastic behavior
The point on the Earth's surface directly above the point where an earthquake occurs is termed the
epicenter
At the subduction zone where the Pacific Plate is subducting under the islands of Japan, the Wadati-Benioff zone of deep earthquakes
extends from the trench westward underneath Japan.
Seismic waves travel ________ in solids than in liquids; however, unlike P-waves, S-waves ________ travel through liquids.
faster; can't
Movement along faults often produces a rock formed from sharply angled rock fragments termed ________.
fault breccia
The distinction between joints and faults is that ________.
faults are fractures along which displacement has occurred; displacement does not occur along joints
What is the best way to describe stress?
force per area
The idea that the continents had once fit together as a single supercontinent called Pangaea was rejected when first proposed because
geologists did not know of a force great enough to move continents.
At any point along the surface of any nonvertical fault, as is shown in the figure below, the
hanging wall lies vertically above the footwall.
The portion along a fold where curvature is the greatest is termed the fold ________.
hinge
Hot spots are caused by
hot plumes of mantle material that rise up through cooler, denser surrounding rock.
The point within the Earth where an earthquake originates is termed the
hypocenter
With increasing distance from a mid-ocean ridge, the age of oceanic crust
increases.
At a subduction zone, the downgoing (subducting) plate
is always composed of oceanic lithosphere.
If a P-wave is traveling through the Earth and encounters a molten magma chamber, what will happen to the velocity of the P-wave?
it will decrease
If an S-wave is traveling through rock when it encounters a molten magma chamber, what will happen to the velocity of the S-wave?
it will not travel through the magma
If you stand on one side of a strike-slip fault and the block on the other side of the fault has moved to your left, this is known as a(n) ________.
left lateral fault
What type of fault is illustrated in the figure?
left lateral strike slip
If a fault is nearly vertical in orientation and the two walls of rock on opposite sides slide past one another horizontally, the fault is termed a ________ fault. Refer to the figure below for an example of such a feature.
left lateral strike-slip
The sides of a fold, where curvature is at a minimum, are termed ________.
limbs
Wet and unconsolidated substrates are uniquely susceptible to ________ during an earthquake.
liquefaction
A very active fault zone in a lightly populated part of the world poses a
low risk and large hazard
Marine magnetic anomalies in oceanic crust result from seafloor spreading in conjunction with
magnetic polarity reversals.
Aftershocks after a major earthquake
may continue for days, weeks, or years after the initial earthquake.
Which earthquake scale is used to assess the effects of an earthquake on humans and human-made structures?
mercalli scale
What kind of plate boundary is shown in the image below
mid ocean ridge
Marine magnetic anomaly belts run parallel to
mid-ocean ridges.
What kind of fold is shown in the image?
monocline
Most earthquakes are a result of
movement of rocks along faults
In a ________ fault, the fault plane is non-vertical and the hanging wall block moves downward relative to the footwall block.
normal
What type of fault is shown below:
normal
Which type of a fault is the result of deformation to accommodate tensile stresses such as those that occur during rifting?
normal
If compressive stresses acting on a rock are greatest in a north-south direction, the rock will likely deform by shortening in a _________ direction.
north-south
Transform plate boundaries are unlike other plate boundaries because
old plate is not consumed nor is new plate created.
On a geologic map, the beds of an eroded anticline will be _________ near the fold hinge compared to further from the hinge.
older
An episode of mountain building is termed a(n) ________.
orogeny
What is the name of the waves shown in box A?
p wave
Which type of seismic wave has the fastest velocity?
p-waver
The study of pre-historic earthquakes is called
paleoseismology
Continental coastlines that occur within the interior of a lithospheric plate are called ___________ margins.
passive
According to the theory of plate tectonics, plates are
pieces of lithosphere that move over the surface of the Earth with respect to one another.
If we assume the seismogram below is a vertical component seismogram (i.e. shows up and down ground motion), what is the name of the type of waves shown in box C?
rayleigh waves
The average length of time between earthquakes along a fault is termed the ______.
recurrence interval
If a fault plane is greater than 30° from horizontal and the hanging wall block moves upward relative to the footwall block, the fault is called a ________ fault.
reverse
What type of fault is shown below:
reverse
What type of seismic wave cannot travel through the outer core
s waves
The energy that is released during an earthquake travels through the Earth as vibrations termed _______.
seismic waves
A ____________ is a scientific instrument used to record the ground motions produced by an earthquake.
seismometer
A body of rock affected by compressive stress will likely undergo ________.
shortening
On either side of a mid-ocean ridge, oceanic lithosphere slowly _________
sinks into the asthenosphere because it cools and thickens, increasing in density.
The core consists of two layers: a(n) ________ inner core and a(n) ________ outer core.
solid; liquid
Periods of intermittent sliding on a fault because of stress release during episodes of slip, followed by stress buildup to the point that the fault is reactivated, are termed
stick-slip behavior
The term for a change in shape induced by stress is ________.
strain
Which of the following is NOT an example of deformation?
stratification