Geology Exam 3

Earthquake A is classified as a 3 on the Richter scale. Earthquake B is classified as a 6. Approximately how many times more energy has Earthquake B released than Earthquake A? -1,000 times -100 times -5 times -33,000 times

1,000 times

When going from a 5 to a 6 on the Richter scale, what is the increase in amplitude of seismic waves? -32 times -2 times -1 time -10 times

10 times

Propagation of fault slip occurs at a rate of about ________ per second. -6 to 20 meters -2 to 4 km -3 to 5 centimeters -20 to 30 micrometers

2 to 4 km

What is the minimum number of points needed to pinpoint the epicenter location of an earthquake, using the radius of a circle of possible points, as obtained from the lag time in arrival between a P wave and an S wave? -2 -3 -4 -5 -6

3

What is a fault? -Foliation in a rock that acts as a plane of weakness -A fracture in a rock along which motion has occurred -A solution pathway created by carbonic acid -A stress fracture created by rocks stretching and pulling apart near the surface

A fracture in a rock along which motion has occurred

What is diffraction? -A seismic wave is bent when moving from one material to another. -A seismic wave is bent when it passes by a curved surface. -Seismic waves are separated by liquids. -A seismic wave is bounced back toward its source.

A seismic wave is bent when it passes by a curved surface.

________ are smaller earthquakes of lesser magnitude, but nonetheless sometimes dangerous, that follow a major earthquake. -Displacement -Aftershocks -Foreshocks -Ripples

Aftershocks

Where is oceanic crust generated? -Where magma bodies are emplaced deep in the crust -Where continents collide -Where volcanic lava meets the sea -Along divergent plate boundaries

Along divergent plate boundaries

In which location on a continent would one be likely to find young mountain belts (less than 100 million years old)? -On the stable platform -In the center of the continent -Along the margins of the continent -On the continental shield

Along the margins of the continent

A relatively weak layer in the Earth due to temperature is known as the ________. -Crust -Mantle -Lithosphere -Asthenosphere

Asthenosphere

Where is the highest rate of heat flow escaping the Earth's interior? -At mountain ranges -At mid-ocean ridges -At volcanoes -At subduction zones

At mid-ocean ridges

What is a mineral phase change? -Atoms in a mineral are rearranged into a denser and more stable structure. -The exterior of a mineral weathers and changes color. -A mineral melts from a solid state to a liquid state. -A mineral changes density because of the addition of water.

Atoms in a mineral are rearranged into a denser and more stable structure.

Which of the following are examples of fault-block mountains? -Rocky Mountains -Alps -Basin and Range -Himalayas

Basin and Range

Where is the thinnest continental crust in North America? -Mississippi River Valley -Appalachian Mountains -Colorado Plateau -Basin and Range region

Basin and Range region

What are the two categories of seismic waves? -Air waves and ground waves -Compression waves and tension waves -Primary waves and secondary waves -Body waves and surface waves

Body waves and surface waves

Which of the following scenarios would best indicate that a thrust fault is present at a location? -Two parts of the same rock have been horizontally displaced by 20 feet -The crust has lengthened, allowing a graben to slip down and create a pull-apart basin -Cambrian-aged rocks have been shoved on top of Jurassic-aged rocks -Th hanging wall of the fault has slipped

Cambrian-aged rocks have been shoved on top of Jurassic-aged rocks

Most mountain ranges are the result of ________ stress. -Shear -Compressional -Tensional

Compressional

What is the source of the sediments in a forearc basin? -Continental sediments and pyroclastic materials -Glacial sediments -Carbonate reefs -Sediments washed from the landmass

Continental sediments and pyroclastic materials

Which process is responsible for Earth's magnetic field? In which layer does this process occur? -Radiation; upper mantle -Crystallization; inner core -Subduction; lower mantle -Convection; outer core

Convection; outer core

Which plate boundary type along the Circum-Pacific Belt is responsible for the majority of that belt's earthquakes? -Transform -Convergent -Divergent

Convergent

Which tectonic boundary is associated with compressional stress? -Transform -Convergent -Dip-slip -Divergent

Convergent

Which tectonic boundary is associated with megathrust faults? -Convergent -Transform -Divergent

Convergent

Which tectonic boundary is responsible for the most powerful and destructive earthquakes recorded? -Convergent -Transform -Divergent

Convergent

Which tectonic boundary would likely have many thrust faults associated with it? -Divergent -Convergent -Transform

Convergent

The ________ layer is thought to have large variations in composition as well as temperature. -A" -B" -C" -D" -E"

D"

Which layer is thought to be the birthplace of deep mantle plumes? -D" layer -Transition zone -Outer core -Shadow zone

D" layer

Put the four regions of a subduction zone in order from the convergent boundary landward toward the continental interior. -Volcanic arc, deep-ocean trench, forearc region, back-arc region -Forearc, back-arc, deep-ocean trench, volcanic arc -Back-arc region, volcanic arc, forearc, deep-ocean trench -Deep-ocean trench, forearc region, volcanic arc, back-arc region

Deep-ocean trench, forearc region, volcanic arc, back-arc region

________ refers to the changes in shape or position of a rock body in response to differential stress. -Brittle Failure - Compression -Stress -Deformation

Deformation

Which physical property was responsible for determining how Earth materials separate into interior layers at the time of Earth's formation? -Density -Color -Tensile Strength -Molecular change

Density

________ is the process where materials separate into different layers due to density. -Phase change -Differentiation -Tensional Stress -Shearing

Differentiation

________ is the angle of inclination of the surface of a rock unit measured from a horizontal plane. -Faulting -Dip -Strike -Plunge

Dip

Which tectonic boundary would have many normal faults associated with it? -Convergent -Transform -Divergent

Divergent

You are accuracy-checking a geologic map of a structural dome with the inner layers dating back to the Paleogene and its outer layers dating back to the Permian. You immediately know this map is wrong. What is your evidence? -Domes don't have layers -Now that we know the age of the layers, we could call it a syncline -Domes have older layers in the middle, not the youngest -Domes didn't exist back then

Domes have older layers in the middle, not the youngest

Unbending a paper clip wire is an example of what kind of deformation? -Shear deformation -Ductile deformation -Brittle deformation -Elastic deformation

Ductile deformation

The elastic rebound associated with earthquakes is an example of ________ behavior. -Permanent -Ductile -Brittle -Elastic

Elastic

A rubber band being stretched in preparation to fire across the room is an example of what kind of deformation? -Shear deformation -Ductile deformation -Brittle deformation -Elastic deformation

Elastic deformation

What is the term used to describe slow, gradual displacement along a fault without the accumulation of significant strain? -Fault creep -Megathrusting -Elastic rebound -Fault propagation

Fault creep

________ is a measurement of displacement on the fault surface. -Fault propagation -Fault slip -Fault creep -Divergence

Fault slip

During an earthquake, energy waves radiate outward in all directions through the interior from the ________ whereas energy waves radiate outward in all directions along the surface from the ________. -Focus; epicenter -Hypocenter; focus -Megathrust; fault -Epicenter; focus

Focus; epicenter

Which of the following regions of a subduction zone is characterized by thick sequences of relatively undeformed sedimentary rocks? -Suture -Transform Fault -Volcanic island arc -Forearc region

Forearc region

A ________ occurs when an iron-rich fluid in the core is electrically charged and flowing, which generates a magnetic field. -Geophysical anomaly -Geosyncline -Geotherm -Geodynamo

Geodynamo

Which of the following terms describes the increasing downward force on basal rocks as a mountain continues to grow? -Accretion -Delamination -Isostacy -Gravitational collapse

Gravitational collapse

Which of the following researchers coined the term elastic rebound after the 1906 San Francisco earthquake? -Charles Richter -Zhang Heng -H. F. Reid -Giuseppe Mercalli

H.F. Reid

Folds form in ________ temperature-________ pressure environments. -High; low -Low; high -Low; low -High; high

High; high

Movements along normal faults can produce alternating upthrown and down-dropped fault blocks. What are the names associated with these blocks, respectively? -Domes and basins -Synclines and anticlines -Horsts and Grabens -Left-lateral and right-lateral

Horsts and Grabens

If the outer core is cooler than the inner core, why is it in a liquid state? -It has greater water content than the inner core -It has higher density materials than the inner core -It has more radioactivity than in the inner core -It is under less pressure than the inner core.

It is under less pressure than the inner core.

You are a seismologist and are driving out to a location where a fault has recently shifted. When you arrive at the location, you see that the road you are driving on was constructed across the fault line. Because of slippage along the fault, the road ahead has been shifted to the left by 20 feet. What kind of fault is present? -Left-lateral strike-slip -Normal -Right-lateral strike-slip -Thrust

Left-lateral strike-slip

What physical property of continents makes them difficult to subduct? -Low density -Age -Temperature -Thickness

Low density

Faults form in ________ temperature-________ pressure environments. -High; low -Low; high -Low; low -High; high

Low; high

Which layer or layers of the interior are believed to have convection cells? -Outer core and inner core -Inner core -Mantle and outer core -Mantle

Mantle and outer core

Which of the following materials would cause the greatest gravity anomaly? -Quartz -Granite -Water -Metallic Ore

Metallic Ore

The ________ is a seismic boundary between the crust and the mantle where there is a dramatic increase in seismic wave velocity. -Moho boundary -Schrodinger discontinuity -Greenschist Facies -Low-velocity pathway

Moho boundary

The ________ is a newer scale that measures the total energy released during an earthquake by determining the average amount of slip on the fault, the area of the fault surface that slipped, and the strength of the faulted rock. -Beaufort Scale -Richter Scale -Mercalli Intensity Scale -Moment Magnitude Scale

Moment Magnitude Scale

The suspended weight in a seismograph allows it to remain ________, which allows it to give a wave reading after the earth moves. -Fractured -Motionless -Propagated -Horizontal

Motionless

A ________ fault is created when the hanging wall moves down relative to the footwall. -Strike-slip -Normal -Graben -Reverse

Normal

Detachment faults are low-angle ________ faults. -Normal -Thrust -Reverse -Stirk-slip

Normal

Fault-block mountains are created due to ________ faults. -Thrust -Normal -Strike-slip -Reverse

Normal

Which of the following best describes the age relationship of the layers in a syncline? -Horizontal bedding with the youngest layers on the top -Oldest materials thrust up on top of younger layers -Oldest on the outside of the fold, youngest on the inside -Oldest on the inside of the fold, youngest on the outside

Oldest on the outside of the fold, youngest on the inside

Which seismic waves would be most useful in determining the extent and thickness of the Earth's interior layers? -P and S waves -P and L waves -L and G waves -S and L waves

P and S waves

Which seismic waves are released first during an earthquake? -L waves -R waves -P waves -S waves

P waves

How will strike and dip marks be oriented on the geologic map of a nonplunging syncline? -Strikes intersecting, but no dips because of horizontal layering -Parallel strikes with dips pointing toward from the center of the fold -Parallel dips with strikes pointing away from the center of the fold -Strikes ringing the fold with the dips pointing toward the center

Parallel strikes with dips pointing toward from the center of the fold

What are slickensides? -Polished and striated surfaces made on fault blocks -Folded rocks along a convergent boundary -Joints made as an igneous rock cools and contracts -Fractures made in a rock as a result of tensional stress

Polished and striated surfaces made on fault blocks

Which of the following rocks would be more likely to experience brittle deformation rather than ductile deformation when subjected to stresses that exceed their strength? -Rock salt -Sandstone -Schist -Quartzite

Quartzite

Which of the following factors contributed toward the early increase in temperature in the Earth's interior? -Radioactive decay and impact from planetesimals -Impact from planetesimals -Friction between landmasses and radioactive decay -Friction between landmasses

Radioactive decay and impact from planetesimals

A(n) ________ fold has limbs that are tilted beyond the vertical to the point that the axial plane is horizontal, giving it the appearance of lying on its side. -Inverted -Plunging -Recumbent -Overturned

Recumbent

Which of the following materials will allow for the fastest transmission of seismic waves? -Partially molten material -Molten material -Material that has been slightly heated -Rigid, less compressible material

Rigid, less compressible material

Why is conduction not an efficient way to move heat through most of the Earth? -Molecules are too far apart to transfer heat via that method. -Radiation is the most efficient way to move heat through the interior. -Rocks are poor conductors of heat. -Radioactive decay generates too much heat.

Rocks are poor conductors of heat.

What is the term for stored-up energy released by earthquakes? -Seismic -Geophysical -Structural -Tectonic

Seismic

________ is a technique to view three-dimensional changes in composition and density by using seismology. -Magnetometry -Seismic tomography -Chemical convection -Paleomagnetism

Seismic tomography

What is the primary method scientists use to determine the layering of the interior of the Earth? -Drill cores -Seismic waves -Volcanic rocks -Sonar

Seismic waves

________ are records of seismic waves. -Seismometers -Seismic relays -Seismographs -Seismograms

Seismographs

________ are instruments that sense earthquake waves and transmit them to a recording device. -Seismometers -Seismic relays -Seismology -Seismograms

Seismometers

How does the angle of subduction affect the dimensions of the forearc basin? -Shallow angle of subduction leads to a wide forearc basin -Steep angle of subduction leads to a wide forearc basin -Steep angle of subduction leads to a narrow forearc basin -Shallow angle of subduction closes the forearc basin

Shallow angle of subduction leads to a wide forearc basin

________ are responsible for the heat generated in the interior today. -Nuclear reactions -Meteorite impacts -Magma plutons -Short-lived radioactive isotopes

Short-lived radioactive isotopes

How does compressional force change a rock body? -Strech and thin the rock -Shorten and thicken the rock -The rock will not chance -Fracture the rock and grind the pieces alongside each other

Shorten and thicken the rock

A chocolate bar will behave similarly to a rock. If you try to bend a chocolate bar at room temperature it will ________ exhibiting ________ behavior. -Bend; brittle -Bend; ductile -Snap; ductile -Snap; brittle

Snap; brittle

How does tensional force change a rock body? -Strech and thin the rock -Shorten and thicken the rock -The rock will not chance -Fracture the rock and grind the pieces alongside each other

Stretch and thin the rock

________ is the compass direction of the line produced by the intersection of an inclined rock layer with a horizontal plane. -Angle -Dip -Strike -Plunge

Strike

The San Andreas Fault is a ________ fault. -Thrust -Reverse -Strike-slip -Normal

Strike-slip

The ground shaking produced by large earthquakes is not only ________, but takes a ________ time than shaking produced by slippage along small fault segments. -Stronger; longer -Weaker; shorter -Weaker; longer -Stronger; shorter

Stronger; longer

Which of the following is the best description for structural geology? -Study of intergrown mineral crystals in igneous rocks -Study of earthquakes and how they move through Earth's interior -Study of rock deformation in response to tectonic forces -Study of sequences of sedimentary rocks and how their environments of deposition dictate how sediments are laid down

Study of rock deformation in response to tectonic forces

Generally speaking, which seismic waves will have the greatest amplitude on a seismogram? -S waves -Surface waves -P waves

Surface waves

Which factor(s) will most influence the depth of deep-ocean trenches? -Temperature and density of the plate -Density and composition of the mantle beneath -Rate of convection -Compressive force

Temperature and density of the plate

How is the shape of the Earth affected by its rotation? -Earth is perfectly spherical. -The equator is further from the center of Earth than the poles. -The earth is more elongate at 45 degrees North and South latitude as compared with elsewhere. -The poles are further from the center of Earth than the equator.

The equator is further from the center of Earth than the poles.

What is the definition of the focus? -The location where three monitoring stations overlap -The build-up of potential energy in a new location after an earthquake -The location on Earth's surface directly above the point of slippage -The exact location on the fault where slippage occurs

The exact location on the fault where slippage occurs

The inner core is believed to rotate independently from the outer layers of Earth. Why is this possible? -Radioactive decay generates spin. -The immense interior pressures generate rotation. -Frictional drag pushes the inner core at a different rate than the rest of the planet. -The inner core is separated from the mantle by the liquid outer core and can spin freely.

The inner core is separated from the mantle by the liquid outer core and can spin freely.

What is the outcrop pattern of a plunging syncline? -The layers will open up in the direction of the plunge -The layers will close to a point in the direction of plunge -The layers will intersect at right angles -The layers will be oriented parallel to each other

The layers will open up in the direction of the plunge

What is an epicenter? -The exact location on the fault where slippage occurs -The location on Earth's surface directly above the point of slippage -The location of migrating magma in the crust -The contact point between two tectonic plates

The location on Earth's surface directly above the point of slippage

What is the major difference between the inner core and the outer core? -The outer core is solid while the inner core is liquid. -The inner core is mostly iron and magnesium while the outer core is mostly silicon and oxygen. -The outer core is mostly iron and magnesium while the inner core is mostly silicon and oxygen. -The inner core is solid while the outer core is liquid.

The outer core is solid while the inner core is liquid.

How would the angle of subduction of a tectonic plate influence the location of a volcanic arc? -The steeper the angle, the closer the arc would form to the trench -The shallower the angle, the closer the arc would form to the trench -The angle of subduction doesn't affect the location of the volcanic arc -The steeper the angle, the further the arc would form to the trench

The steeper the angle, the closer the arc would form to the trench

What information is needed to determine the distance from the focus of an earthquake to the seismic receiving station? -The time interval between the P and S waves -The magnitude of the earthquake -The amplitude of the seismic waves on a seismogram -The velocity of the P and S waves

The time interval between the P and S waves

What will happen to a seismic wave when it is refracted? -The wave will be bounced back toward its source. -The wave will be bent when passing into a material of differing density. -The wave will undulate. -Nothing will change the wave.

The wave will be bent when passing into a material of differing density.

What will happen to a seismic wave when it is reflected? -The wave will undulate. -The wave will be bounced back toward its source. -The wave will be bent. -Nothing will change the wave.

The wave will be bounced back toward its source.

Why do seismic waves follow strongly curved paths as they move through the interior? -Their velocities are altered by changes in chemistry. -Their paths are altered by changes in temperature. -Their velocities are changed because of increasing pressure with depth. -Their paths are altered by reflection off dense materials.

Their velocities are changed because of increasing pressure with depth.

The Cascadia subduction zone off the coast of Washington and Oregon famously lacks a well-defined deep-ocean trench. Why might this be the case? -The descending plate is warm and buoyant, so it subducts shallowly. -There is a shallow angle of plate subduction, as well as large quantities of sediment infill. -Compression from the convergent boundary has squeezed any potential trench closed. -There is a massive amount of sediment fill from the Columbia River basin.

There is a shallow angle of plate subduction, as well as large quantities of sediment infill.

Mountain ranges such as the Appalachians and the Himalayas are examples of mountains that formed as a result of ________ faulting. -Normal -Transform -Thrust -Strike-slip

Thrust

Which of the following would be the most unstable during an earthquake? -Unconsolidated Sediments -Crystalline bedrock -Sedimentary strata -Concrete foundations

Unconsolidated Sediments

Which of the following best describes a seismic gap? -Faults that have not been active for several million years -Unusually quiet zones along typically active faults -A down-dropped valley bound by normal faults -An erosional valley that has developed in an inactive fault

Unusually quiet zones along typically active faults

What is the highest level on the Mercalli Intensity Scale? -XV -X -XII -IX

XII

The Modified Mercalli scale is ________. -based entirely on direct readings from seismographs -originally proposed by Charles Richter -takes into account how much earth was displaced -still used today by the U.S. Geological survey to gather data from those who felt an earthquake

still used today by the U.S. Geological survey to gather data from those who felt an earthquake ????