Geo Final
which layer is the weak plastic layer on which the lithospheric plates slide
asthenosphere
prior to wegeners development of the theory of continental drift, the prevailing view of geologists was that
earths continents developed during the initial formation of earth and remained permanently fixed in position throughout geologic time
a characteristic of elastic deformation is
it is recoverable in that the original shape returns after the applied stress is released
for earthquakes in the crust the largest amplitude waves tend to cause most of the damage are
surface waves
Which building shown in Figure 5 would have the lowest resonance frequency
tallest building
the 1964 alaska earthquake the second most powerful earthquake recorded in the last 100 years and yet because of low population density only 131 people died what was the main cause of those deaths
tsunamis flooded the costal lines
p waves travel at about
twice the speed of s waves
the himalayan mountain belt is an example of a tectonic setting in which
two continental blocks are colliding
the modern theory of the origin of earthquakes originally proposed by Henry Reid holds that during the time interval between earthquakes the region to either side of the earthquake producing faults
undergo slow elastic deformation with little or no slip across the fault
Which two features are used to determine the surface wave magnitude
wave length and height of the wave
Which volcano type is formed completely of basalt lava flows?
Shield
Which volcano type is most common at oceanic hot spots
Shield
which tectonic setting is where continental collision occurs
--> <-- convergent
the oldest rock found in oceanic crust approach
200 million
so called great earthquakes are earthquakes of magnitude 8.5 and larger how often do such earthquakes occur worldwide
1 every 3 years
how fast do the tectonic plates that make up earths surface move
1 to 10 cm per year
Geologic study of the past earthquake activity along the South-Central San Andreas fault, north of Los Angeles, indicates that the average time interval between magnitude 7.0 or larger earthquakes is about:
235 yrs
the oldest whole rocks found in continental crust approach
4 billion
The pattern of past earthquakes in the San Francisco Bay area suggests:
70% chance of a magnitude 6.7 or greater earthquake before 2030.
According to paleoseismic evidence, which fault segment shown in Figure 1 has highest probability of having an earthquake of magnitude 6.7 or greater by 2030?
A
Explosive volcanic eruptions will occur most often on which boundary,
Convergent
Which segments of the San Andreas Fault shown in Figure 1 have produced earthquakes of magnitude 7.5 or greater in historic time (since 1800)?
A and C
The best long-term earthquake forecasting on the scale of decades for particular fault segments is based on:
A combination of the historic records plus the geologic record of fault rupture.
The main eruption of Mt Saint Helens on May 18, 1980, that caused complete destruction out to distances of 15 miles from the volcano, started with:
A large portion of the mountain collapsing in a giant landslide.
Which earthquake magnitude scale is most useful for determining the magnitude of deep earthquakes with focal depths greater than 400 km
Body Wave magnitude
Mt Rainier, 40 miles southwest of Seattle, Washington has been called "North America's most dangerous mountain", because of the risk of which hazardous event:
A spontaneous mudflow without an eruption.
Which volcano type has the most violent and dangerous eruptions
Caldera
Which site(s) shown in Figure 2 has(have) experienced a magnitude 7.5 or greater earthquake in the last 400 years?
All four ( california utah missouri south carolina)
Earthquakes in the US east of the Rocky Mountains tend to occur:
Along old weaknesses in the continental crust.
Which fault segment shown in Figure 1 tends to produce a magnitude 6 earthquake every 22 years, but no large earthquakes?
B
Silica-rich volcanic rocks will be more common on which boundary?
Convergent
Adjacent to which of the three plate boundaries, labeled A, B, or C in Figure 4, would you expect to find no volcanic activity?
Boundary near northern california
Which fault segment shown in Figure 1 is associated a with restraining bend in the fault?
C
Which volcano type is made of alternating pyroclastic and viscous lava flows
Composite
Which volcano type is most common adjacent to subduction zones
Composite
Composite volcanoes have:
Curved cone shape and alternating layers of ash, debris and lava.
Which fault segment shown in Figure 1 last produced a magnitude 7.7+ in the late 1600s?
D
The pattern of deposits from past eruptions of Mount Shasta indicates that risk associated with pyroclastic flows:
Decreases uniformly with distance away from the volcano.
Low-silica volcanic rocks will be more common on which boundary
Diverge
Peaceful lava flows will be more common on which boundary?
Diverge
The study of earthquakes is important to the study of volcanic eruption prediction because:
Earthquakes beneath dormant volcanoes are a good indicator of renewed volcanic activity.
Seismic gaps along earthquake producing faults are thought to be places where:
Earthquakes have not occurred recently, but are likely occur in the near future.
Shield volcanoes tend to erupt by:
Emitting rivers of lava that flow for miles.
The rock record of ejected material from past volcanic eruptions gives clues about:
Eruption type, size and how often eruptions occur.
Attempts to predict earthquakes on time scales of days or weeks before the event are based on looking at:
Events or physical changes in rock properties within the fault zone before the quake.
Tsunami waves differ from wind-driven waves in the ocean in that the motion within the tsunami wave:
Extends all the way to the seafloor.
The mechanism by which tsunamis propagate differs from the other forms of seismic waves in that the energy contained in tsunami waves is alternately stored as:
Gravitational potential of water and motion of the water.
The presence of large glaciers on top of many Cascade Range volcanoes tends to:
Greatly increases the danger because of the increase in mudflow potential.
Groundwater plays what role in the volcanic eruption process?
Groundwater is drawn into the magma chamber and causes the pressure inside to increase.
Evidence that the Cascadian Trench, along the US Pacific Northwest coast, is one 1200 km long seismic gap was recognized from:
Groves of dead trees along the coast.
The viscosity of magma with relatively high silica content is relatively:
High
The pattern of deposits from past eruptions of Mount Shasta also indicates that risk associated with mudflows:
Is mainly in the river valleys flanking the volcano.
The major risk of damage to housing subdivisions at the foot of Kilauea, Hawaii is:
Lava flows and fissure eruptions.
Paleoseismology results indicate that damaging earthquakes on individual segments of the Wasatch fault likely occur:
Less often as earthquakes on segments of the San Andreas Fault
To avoid the tsunami hazard on the Pacific and Indian Ocean shorelines, buildings should be:
Located on land that is at least 100 ft above sea level.
The viscosity of magma containing relatively high amounts of dissolved gas, such as water vapor and carbon dioxide is relatively:
Low
The viscosity of magma with relatively high temperature is:
Low
Over the last 30 years, the track record on long-term earthquake forecasting on time scales of decades has been:
Many correctly forecasted earthquakes, but there have been cases of smaller earthquakes and longer periods between quakes than expected.
The status of short-term earthquake prediction on time scales of days or weeks is that:
Many potential earthquake precursors have been evaluated, but none have work consistently.
When a tsunami is believed to be approaching a shore near you, you should:
Move inland and to higher elevation as fast as possible.
Tsunami waves traveling across the deep ocean basins travel at speeds that are:
Much slower than normal seismic waves.
Tsunami waves traveling across deep ocean basins are characterized by:
Periods of an hour or more and heights on the sea surface of only a meter or two.
Which of the following eruptive styles is the most violent?
Plinian
The summit of Mt Vesuvius, a stratovolcano, is located 12 kilometers from the center of Naples Italy, with a population of over 3 million people. It has no permanent ice on its summit. What is likely the greatest hazard posed to the lives of the people of Naples from this volcano?
Pyroclastic flows.
he status of an earthquake warning system on the US west coast, which would warn people of approaching seismic wave on time scales of a few 10s of seconds is that:
Reliable approaches have been found, but the instrumentation needed to monitor each fault segment is not yet in place to implement on a large scale at this time.
. The magma type that contains the largest proportion of silica is:
Rhyolite
What is main driver of explosive volcanic eruptions?
Steam from water infiltrating the magma chamber.
Earthquakes begin when
Stress in rock adjacent to the fault equals or exceeds the friction on the fault.
What type of tectonic plate setting has historically produces the most tsunamis?
Suduction zones
Which earthquake magnitude scale is most useful for making quick estimates of the magnitude of small earthquakes observed at great distances
Surface Wave magnitude scale
Which earthquake magnitude scale is most useful for determining the relative size of a great earthquake with magnitude greater than 8.5
The Moment Magnitude scale
On Hawaii, Pahoehoe lava flows and Aa lava flows are both composed of basalt. They differ in their physical appearance because:
The Pahoehoe lava has a lower viscosity because it is hotter and has higher water content.
The speed at which tsunami waves travel is controlled by:
The depth of the water in which it travels.
. The Wasatch fault of Utah is an example of a fault not associated with a plate boundary that represents a potential seismic risk to population centers. Motion on this fault is caused by the fact that:
The motion between the Pacific and North American plates is not parallel to the San Andreas Fault.
Which statement best characterizes the hazards associated with pyroclastic flows?
The risk to both people and property is high 10 to 20 km from the volcano.
which statement best characterizes the hazards associated with mudflows?
The risk to both people and property is high in river valleys 40 to 60 of kilometers from the volcano.
Which statement best characterizes the hazards associated with lava flows?
The risk to people is low, but there is high risk to property 10 to 20 km from the volcano.
Dilatancy in rock adjacent to faults occurs when:
The rock volume increases due to relative movement of grains in the rock.
The fact that the Pacific coast of the states of Washington and Oregon are rising at a rate of 5 to 6 millimeters per year is thought to be due to:
The subducting Juan de Fuca Plate being locked to the edge of the North American Plate.
The formation of the Cascade Range volcanoes in the Pacific Northwest is associated with:
The subduction of the Juan de Fuca Plate under North America
Increases in gas emissions from volcanoes and the temperature of hot springs on volcanoes indicate:
The upward movement of magma from the magma chamber into the volcano.
The most common cause of tsunamis since good record keeping began in 1790 has been
The vertical motion of the seafloor during earthquakes.
Increases in elevation of the summit or outward tilt of the flanks of a volcano over periods of weeks or months can mean:
The volcano is beginning a new active phase
The Volcanic Explosive Index scale is determined primarily from:
The volume of the erupted material.
The main factor that increases the earthquake hazard to down town Mexico City compared to neighboring areas is:
The weak lake sediments that underlying that part of the city.
The May 18, 1980 eruption of Mt Saint Helens ejected 0.2 cubic miles of material. Compared with past eruptions of this and other volcanoes, the 1980 eruption:
Was smaller than many eruptions in both recorded history and the geologic record.
One of the main differences between efforts to avoid the hazards from tsunami vs normal seismic waves is that:
We have the technology to warn many people hours in advance of tsunami arrival.
Few or no volcanoes will be found on which boundary
Transform
Another way in which tsunami waves differ from other seismic waves is that:
Tsunamis can cause damage and kill people thousands of kilometers from the epicenter
Volcanologists are better able to warn people of impending volcanic eruptions than seismologists are able to predict earthquakes because:
Volcanoes often show clearer signs they are becoming active before major eruptions.
One of the main earthquake hazards in modern cities is the disruption of transportation due to the collapse of highway overpasses supported by reinforced concrete columns. What is one of the main ways these concrete columns are retrofitted to better survive earthquakes?
Wrapping the concrete columns in steel shells.
s waves that reach the base of the mantle and top of the outer core
are not transmitted into the core
typical continental lithosphere is made of
a brittle upper crust ductile lower crust and brittle uppermost mantle
the submerged mountain belt that wraps around earth in the middle of the oceans stand 4 kilometers above the adjacent seafloor the weight of these mountains is supported by
a region of hot upper mantle directly beneath mountains caused by upwelling asthenosphere
Existing buildings can be made more earthquake resistant by: a. Wrapping concrete columns in steel.
b. Reinforces the joints between beams. c. Adding external triangular trusses. d. Adding internal shear walls.
Adjacent to which boundary would you expect to find an average of andesitic lava compositions being produced?
boundary by oregon
Adjacent to which boundary would you expect to find the highest concentration of composite volcanoes
boundary by oregon
Adjacent to which boundary would you expect to find volcanoes that produce pyroclastic flows?
boundary by oregon
Adjacent to which boundary would you expect to find only basalt lava being produced
boundary by washington
Which building shown in Figure 4 above would tend to suffer the greatest damage in an earthquake
brick
Which building shown in Figure 4 would support large vertical loads, but would quickly fail in response to horizontal loads
brick
scientific hypothesis are theories that are both scientific ideas
but hypotheses are more consistent with existing observations at the time they are proposed whereas theories have also correctly predicted new observations
the ground elevation of parts of canada is rising several centimeters per year because
canada is moving over a hotspot and is being heated by the upwelling mantle
Earthquake intensity is determined by
categorizing the severity of damage associated with the quake
which region contains rock with the most silica rich composition
continental crust
which plate boundary produces the largest number of earthquakes
convergent
which plate boundary type produces the most powerful earthquakes
convergent
which tectonic setting is where old ocean lithosphere is recycled back into the mantle
convergent ( but where the arrows are overlapping each other
which layer is composed of iron in solid form
core
which region is composed almost completely of iron
core
which type of crust contains the oldest rocks found on earth
core
S waves are represented by paths that look like
defracted waves
the amount of energy released during an earthquake or so called seismic moment is directly controlled by which 3 factors
displacement across the fault, the rupture area, and the strength of adjacent rocks
Which two features are used to determine the distance from the earthquake epicenter to the recording seismic station
distance from P wave to S wave
which plate boundary is the lithosphere the weakest
divergent
which plate boundary type produces mostly small earthquakes
divergent
which tectonic setting is where new oceanic lithosphere is formed
divergent
damage caused by the 2011 magnitude 9 earthquake in japan was greatly increased by what human factor
flooding by the associated tsunami caused the meltdown of three nuclear reactors
what aspect of the fossil record did wegener use to support his theory of continental drift
fossils older than 120 million years are the same in africa and south america whereas young fossils differ
Due to differing foundation materials, which of the buildings shown in Figure 3 would tend to sustain the least damage in an earthquake
hard bed rock
What property of silica causes it to control the viscosity of magma?
he tendency for silica to form chain and sheet molecules.
the biggest weakness is wegener's original continental drift hypothesis was
his idea that continental crust slides over the seafloor is not mechanically feasible
a characteristic of brittle deformation is
it is promoted by low pressure and rapid deformation
the east African rift system is a 3000 km long zone in which Africa is being pulled apart. seismic activity along that boundary can be characterized as
infrequent small earthquakes in the 4-5 magnitude range with some magnitude 6
a characteristic of ductile deformation is
it is promoted by high temp and slow deformation
which layer acts as a rigid shell broken into separate pieces
lithosphere
richters original magnitude scale is still used under a different name what is richter's original scale called now
local magnitude
which region contains rock with the most iron and magnesium rich composition
mantle
the moderate strength (6.7 mag) 1994 northridge earthquake in southern california produced the largest monetary loss of any earthquake in us history what was the main factor that greatly increased monetary loss
many buildings and bridges made of reinforced concrete failed
since reid proposed his theory of earthquake occurrence his proposed mechanism of earthquake energy accumulation and release has been verified by
measuring the change in ground surface elevation before and after earthquakes
which layer is the strong plastic layer that slowly convects heat from the core to the asthenosphere
mesosphere
At which sites would the areas in which damage could occur due to a 7.5 or greater earthquake be the largest?
missouri and south carolina
seismic tremor which involves low intensity shaking that lasts for weeks occurs
near the bottom of the lower crustal ductil zone
Which fault type forms by extension
normal
Which fault type is most common on divergent plate boundaries
normal
which type of crust has the highest density
oceanic
1886 Charleston, South Carolina earthquake is estimated to have had a magnitude in the mid 7s what evidence did scientists use to estimate the magnitude of this earthquake
old newspaper accounts of the effects of the quake throughout the eastern US
Which melting point diagram in Figure 3 produces melts that tend to evolve into a mixture of basalt, andesite, and rhyolite lavas at the surface?
one where melt section is bigger
which tectonic setting is where lithosphere moves over a fixed hot spot in the mantle
one where one arrow is pointing sideways and the other is under it pointing up
Which melting point diagram in Figure 3 tends to results in exclusively low viscosity lavas at the surface in oceanic settings?
one where solid section is bigger
which layer is the only layer of the solid earth that is liquid enough to pore
outer core
4 of the 5 most powerful earthquakes in history were associated with which tectonic setting the
pacific belt of subduction zones v
Which building shown in Figure 4 would tend to support short-term earthquake loads, but would tend to crumble and collapse after repeated cycles of shaking
reinforced concrete
In the earthquake design of large office buildings, engineers choose the building height primarily so that the building's:
resonance frequency differs from the frequency of the seismic waves.
Which fault type is most common on convergent plate boundaries
reverse
a key point in understanding how plate tectonics is possible was the recognition that
rocks that behave like solids in terms of transmitting seismic waves can behave like liquids at geologic time scales
which of the following statements is not necessarily true of scientific ideas
scientific ideas are that have been proven to be correct
in the modern view of science described by Karl Popper the main characteristics of scientific ideas that distinguish them from other kinds is that
scientific ideas can be tested in a way that could be proven false
the submerged mountain belt that wraps around earth in the middle of the oceans discovered by tharp are now known to be formed by
seafloor spreading
linear stripes pf alternating high and low magnetic anomalies on the seafloor are caused by
seafloor spreading and reversals in the direction of earths magnetic field
the deep trenches in the seafloor adjacent to asia in northwest edge of the pacific ocean were formed by
seafloor subduction
the most important driving force moving the tectonic plates seems to be
slab pull associated with the weight of the down going lithosphere in subduction zones
seismic surface waves travel
slower than s waves
Which of the foundation materials shown in Figure 3 would most likely undergo liquefaction during an earthquake?
soft sediment
Within which of the foundation materials shown in Figure 3 would the amplitude of vibrations from an earthquake be the lowest
soft sediment
Which building shown in Figure 4 would tend to suffer the least damage in an earthquake?
steel frame
Which fault type is most common on transform plate boundries
strike slip
the coldest lithosphere is the
strongest
as p waves travel thru the earth
the alternately compress and dilate the rock
Whats used to determine the Body Wave Magnitude of an earth quake
the amplitude and period of the P wave and the epicentral distance.
which tectonic feature accounts for about 80% of all earthquakes
the circum pacific belt of subduction zones
the damage due to the 1906 earthquake in san francisco was much greater than it would have been if not for what additional human factor
the city gas pipelines broke and produce widespread fire
in his theory of continental drift wegener proposed that
the continental crust slid thousands of kilometers over the seafloor
Airys principle of istosity holds that mountain belts such as the himalayas stand higher than the surrounding regions because
the crust is thicker beneath the mountains and therefore the floats higher on the mantle
it has been observed that earthquakes along the san andreas fault all occur in the upper crust above a depth of 18 km fro what we know a out rock
the lower crust undergoes ductile deformation and does not break
the 5 deadliest earthquakes in history were associated with which tectonic feature
the mediterranean asiatic belt of continental collision
the apparent motion of the magnetic north pole thousands of miles over the seafloor surface of earth through geologic time is actually caused by
the motion of continents
the modern theory of plate tectonics involves
the motion of oceanic and continental lithosphere over the asthenosphere
long linear island chains that become progressively older from one end to the other like the hawaiian chain were formed by
the movement of the seafloor over a hotspot in the mantle
upon what observational evidence did reid base his theory
the pattern of ground displacement along the san andreas fault in response to the 1906 san francisco earthquake
What is the hypocenter of an earthquake?
the point on the fault surface where the fault rupture begins
It is commonly said that earthquakes do not kill people what additional factors are needed to make earthquakes more hazardous
the presence of humans together with structures and facilities inappropriate for earthquake prone areas
the most powerful earthquakes occur in lithosphere that is
the strongest
the thickness and properties of earths internal layers are mainly known from
the time it takes earthquakes to travel through the earth
as seismic waves travel through the interior of earth they curve back toward the surface what characteristics of earth cause the paths of the seismic waves to curve rather than follow straight lines
the velocity of seismic eaves increase with depth in the earth
The shape of volcanoes and the way they erupt are both determined largely by:
the viscosity of the magma that feeds the volcano.
which plate boundary types produces an intermediate number of earthquakes
transform
which seismic station would the P wave be observed but not s waves
where station is not by a wave path thats not shaded
which seismic station would the P wave not be observed
where station is not by a wave path thats shaded
Which building shown in Figure 4 is made of a relatively low-cost building material that can survive earthquakes when combined with quality fasteners in single story homes?
wood frame
the floor of the atlantic ocean is
youngest in the middle and oldest adjacent to north america and africa