final exam written q examples Flashcards
1
Q
EARTH’S STRUCTURE & TECTONICS
A
2
Q
How is it that the compositions of certain types of meteorite represent the bulk composition of planet Earth?
Approximately what age are these meteorites?
A
3
Q
Draw two diagrams, each depicting a cross section through the solid Earth’s interior.
(a) On one diagram, label the major rheological layers stating the basic rheology of each one.
(b) On the other diagram, label the Earth’s main compositional layers, stating the basic chemical composition of each one
A
4
Q
(a) Describe the major differences between oceanic crust and continental crust in terms of their composition and physical properties.
(b) Show how these differences explain the contrast in deformation observed at ocean-continent convergent plate boundaries (subduction zones), versus continent-continent convergent plate boundaries (continental collisions)?
A
5
Q
What are coronal mass ejections, and how do they cause geomagnetic storms?
Describe a few of the human impacts of these event
A
6
Q
Describe one piece of geological evidence in support of the theory of continental drift and one piece of geophysical evidence used to develop the theory of plate tectonic
A
7
Q
Which bathymetric features (bathymetry = sea floor topography), mapped using sonar initially during the Second World War, were later used in the development of the theory of Plate Tectonics?
Illustrate by drawing a schematic cross-section of an ocean-ocean divergent plate boundary and an ocean-continent convergent plate boundary.
A
8
Q
MC
A
9
Q
What is the difference between continental and oceanic crust in terms of density?
Continental crust is denser than oceanic crust.
They have, on average, the same density.
Oceanic crust is denser than continental crust.
A
10
Q
What is the typical geothermal gradient in Earth’s lithosphere?
2.5ºC per kilometer
25ºC per kilometer
250ºC per kilometer
2500ºC per kilometer
A
11
Q
How long do coronal mass ejections take to travel from the Sun to the Earth?
From ∼1 second up to a few seconds
From ∼1 minute up to a few minutes
From ∼1 hour up to a few hours
From ∼1 day up to a few days
A
12
Q
What are the origins of the Earth’s internal heat?
Accretion of material forming the proto-Earth.
Frictional heating during Earth’s differentiation.
Radioactive decay of radioactive elements within the Earth.
All of the above.
A
13
Q
What are the main mechanisms for heat transfer through (a) the lithosphere and (b) the asthenosphere/mesosphere?
(a) Convection; (b) Convection
(a) Conduction; (b) Convection.
(a) Conduction; (b) Conduction.
(a) Convection; (b) Conduction.
A
14
Q
How do the Earth’s crust and lithosphere relate to one another?
The crust contains the lithosphere plus part of the asthenosphere.
Crust and lithosphere are compositional and rheological terms for exactly the same part of the Earth.
The lithosphere contains the crust plus part of the upper mantle.
A
15
Q
What was the Tunguska event?
The most recent reversal of Earth’s geomagnetic poles
An intense geomagnetic storm caused by a massive coronal mass ejection
An air burst due to a large meteor exploding in the atmosphere
A cratering impact event
A
16
Q
What rock type is the upper mantle made of?
Basalt
Granite
Sedimentary rock
Peridotite
A
17
Q
Which class of meteorite describes undifferentiated planetary material?
Chondrites
Iron meteorites
Achondrites
Stony-iron meteorites.
A
18
Q
How is Earth’s age of 4.56 billion years known?
From radiometric dating of chondrite meteorites.
From radiometric dating of the oldest known continental crust.
From radiometric dating of the oldest known oceanic crust.
From calculating the time needed for Earth to cool to its present temperature from an initial molten state.
From counting tree rings at the time of the dinosaurs
A
19
Q
MC
A
20
Q
Why does melting occur at mid-ocean ridges?
Due to higher water content of the mantle.
Due to structural weakness of the crust.
Due to lower mantle pressure.
Due to higher mantle temperatures.
A
21
Q
The Yellowstone hot spot track suggests that the North America plate is moving in which direction?
Towards the north-east.
Towards the south-west.
Towards the north-west.
No direction - it implies that the North America plate is stationary.
A
22
Q
How can hot spots be used as evidence for plate tectonics?
They indicate how the plate has moved over the stationary mantle plume.
Hot spots are evidence against plate tectonics.
They explain why volcanoes occur above subduction zones.
They indicate how the mantle plume has moved beneath the plate
A
23
Q
What is a passive continental margin?
A tectonically inactive plate boundary.
A transition from oceanic to continental crust within the same plate.
An ancient rift attempt that failed to establish a sustained spreading centre.
Any transition from oceanic to continental crust whether or not it is a plate boundary.
A
24
Q
How do you envisage the seismic risk changing in Victoria, BC, over the next fifty years?
Make reference both to the expected rapid population growth, and also to the potential to improve earthquake mitigation and/or preparedness.
A
25
What type of plate boundary does the San Andreas fault represent?
A continental strike-slip boundary.
A continental rift.
A continental collision.
A subduction zone.
26
Victoria is situated closest to the boundary between which tectonic plates?
The triple junction between the North American, Pacific, and Juan de Fuca plates.
The boundary between the North American and Juan de Fuca plates.
The boundary between the North American and Pacific plates.
The boundary between the Pacific and Juan de Fuca plates.
27
Which ocean is characterized by passive continental margins on both sides?
The Indian Ocean.
The Atlantic Ocean.
The Pacific Ocean.
28
Why does melting occur at subduction zones?
Due to lower mantle pressure.
Due to structural weakness of the crust.
Due to higher mantle temperatures.
Due to higher water content of the mantle.
29
Why does melting occur at hot-spots?
Due to higher mantle temperatures.
Due to lower mantle pressure.
Due to higher water content of the mantle.
Due to structural weakness of the crust.
30
What is the relationship between the theories of continental drift and plate tectonics?
Continental drift provides the physical mechanism to explain plate tectonics.
Plate tectonics and continental drift are rival theories that are mutually exclusive.
Continental drift and plate tectonics are different terms for the same thing.
Plate tectonics provides the physical mechanism to explain continental drift.
31
EARTHQUAKES
32
(a) What are the three basic types of fault, and how do they differ?
(b) Which type of fault is responsible for the largest (Mw>8) great earthquakes?
(c) What tectonic setting are these great earthquakes restricted to, and why?
33
What are the main types of seismic wave?
Discuss the basic characteristics of each, in terms of their path, velocity, particle motion, and potential to cause damage.
34
Explain in principle (no need to include any math) how the difference in seismic wave speeds can be:
(a) used to locate an earthquake?
(b) used to provide early warning of imminent ground shaking (“Earthquake Early Warning")
35
What are the basic differences between the earthquake magnitude and intensity scales?
Use a real earthquake case study to illustrate one of the major factors that determines intensity.
36
List some of the factors which control the peak intensity felt during an earthquake.
37
Why are seismic risks increasing through time, even as our understanding of earthquakes improves?
Briefly, what accounts for the large number of devastating earthquakes in the country of Iran (for example, the 2003 Mw 6.6 Bam earthquake)?
38
Briefly explain why in some earthquakes, buildings of a certain height are destroyed, whereas buildings that are shorter or taller withstand the shaking.
You may like to use a recent case study to illustrate.
39
(a) Briefly explain on what kind of geological structures intraplate earthquakes are found.
(b) What are some of the possible driving forces behind intraplate earthquakes.
40
(a) Below is a map of the tectonics of Cascadia. Sketch a simple diagram (not to scale) showing a cross-section of the structure along the line A-A’ indicating oceanic and continental crust, man- tle, lithosphere and asthenosphere; labelling tectonic plates and plate boundaries; and indicating directions of motion.
(b) With reference to your cross-section, what are the three major sources of seismic hazard in this region? How do they differ in terms of the likely earthquake magnitude, depth, and distance from population centres?
41
MC
42
How do earthquake seismograms recorded at larger epicentral distances differ from those recorded at shorter epicentral distances?
At larger epicentral distances, the S waves will arrive on the seismogram before the P waves do.
At larger epicentral distances, the P wave, S wave and surface wave arrivals will be more separated on the seismogram.
At larger epicentral distances, the P wave, S wave and surface wave arrivals will be more closely spaced on the seismogram.
At larger epicentral distances, no surface waves will appear on the seismogram.
43
The photo below shows a surface rupture from a recent earthquake in Taiwan (crossing the athletics track in the middle of the photo). What was the mechanism of this earthquake?
Reverse
Normal
Right-lateral strike-slip
Left-lateral strike-slip
44
What is the earthquake cycle?
The cyclic build-up and release of stress and strain on a fault.
The life cycle of an oceanic normal fault, from when it is formed at a mid-ocean ridge to when it is destroyed through subduction.
The duration of a single earthquake rupture, from when it starts to slip to when it stops slipping.
The return period between large earthquakes as felt at a given location.
45
At which of the following types of plate boundary are reverse/thrust faults most common?
Subduction zones and continental collision zones.
Mid-ocean ridges and continental rifts.
Continental shear zones.
46
What type of strain do normal faults accommodate?
Simple shear
Contraction (shortening)
Extension
47
What best describes earthquake body waves, which travel through the Earth's interior, in relation to surface waves, which travel around the Earth's surface?
Body waves are faster and larger amplitude.
Body waves are faster and smaller amplitude.
They travel at the same velocity, but body waves are larger amplitude.
Body waves are slower and larger amplitude.
Body waves are slower and smaller amplitude.
48
What is the name given to faults that accommodate both vertical and lateral slip?
Oblique slip faults
Mixed mode faults
Splay faults
Bilateral faults
49
What best describes particle motion during the passage of a P-wave?
Compression/tension in the direction that the P-wave travels.
Compression/tension perpendicular to the direction that the P-wave travels.
Shear in the direction that the P-wave travels.
Shear perpendicular to the direction that the P-wave travels.
50
The photo below shows a surface rupture from a recent earthquake in Italy. What was the mechanism of this earthquake?
Reverse
Normal
Right-lateral strike-slip
Left-lateral strike-slip
51
What type of faulting results in crustal thickening?
Normal faulting.
Left-lateral and right-lateral strike slip faulting.
Reverse/thrust faulting.
Left-lateral strike slip faulting.
Right-lateral strike-slip faulting.
52
MC - prt 2
53
What factors could influence the shaking intensity felt during an earthquake at a given location?
The magnitude of the earthquake.
The type of rock in that location (e.g. soft sediment, hard bedrock)
The depth of the earthquake.
The distance to the earthquake epicenter.
All of these factors would influence the felt intensity.
54
The photo shows fracturing of a road caused by a large earthquake in Alaska. Which phenomenon explains why road damage seems to be restricted to the causeway across a low-lying marshy area?
The rupture directivity effect
Earthquake surface rupturing
The basin amplification effect
Liquefaction of water-saturated sediment
55
Given two earthquakes of the same magnitude and depth, one in western North America and one in eastern North America, which will likely be felt over a wider area and why?
Neither will be felt over a wider area, since two earthquakes of the same magnitude and depth will always produce identical patterns of ground shaking
The earthquake in western North America will be felt over a wider area because the western half of the continent contains a much greater density of active faults
The earthquake in eastern North America will be felt over a wider area because of thick sediments underlying the eastern North American passive margin
The earthquake in eastern North America will be felt over a wider area because of the stronger (less fractured) geology underlying the eastern half of the continent
56
The largest magnitude earthquakes are:
Strike-slip earthquakes.
Subduction megathrust earthquakes.
Normal fault earthquakes at mid ocean ridges.
Reverse fault earthquakes in continental collisions.
57
How can the dip angle of the fault influence the magnitude of an earthquake?
Shallow-dipping faults rupture more slowly than steeply-dipping faults, generating smaller magnitude earthquakes.
Shallow-dipping faults have a larger surface area within the brittle upper crust than steeply-dipping faults, giving them greater potential for larger magnitude earthquakes.
Shallow-dipping faults naturally slip more than steeply-dipping faults, generating larger magnitude earthquakes.
Shallow-dipping faults naturally slip less than steeply-dipping faults, generating smaller magnitude earthquakes.
58
In the equation for seismic moment, what does the shear modulus describe?
It describes a material's resistance to deformation by shear stress — or put more simply, its stiffness.
It describes the area of fault that ruptures in an earthquake.
It describes the average slip in an earthquake.
59
Why do sedimentary basins amplify incoming seismic waves (basin amplification)?
Because seismic waves slow down as they pass into loose sedimentary rocks.
Because seismic waves speed up as they pass into loose sedimentary rocks.
Because water-saturated sedimentary rocks liquefy during ground shaking.
60
Which statement best describes earthquake frequency-magnitude relations?
For each unit increase in moment magnitude, there are about ten times more earthquakes.
For each unit increase in moment magnitude, there are about twice as many earthquakes.
For each unit increase in moment magnitude, there are about half as many earthquakes.
For each unit increase in moment magnitude, there are about ten times fewer earthquakes.
61
How much more seismic moment is there in a Mw 6.0 earthquake than in a Mw 5.0 earthquake?
6/5 = 1.2 times as much.
10 times as much.
(6/5) x 10 = 12 times as much.
101.5 = 32 times as much.
62
What is the truest measure of the energy released by an earthquake?
Its maximum intensity on the Mercalli scale.
Its seismic moment.
Its Richter scale magnitude.
Its rupture velocity (the speed at which the earthquake propagates along the fault).
63
MC. - prt 3 (case studies)
64
Which aspects of the 2011 Mw 9.0 2011 Tohoku earthquake took scientists by surprise?
Its rupture area, average slip, and moment magnitude were all much greater than expected.
It generated a larger tsunami than was anticipated.
It slipped all the way to the surface (the sea-floor at the trench).
All of the above.
65
During the interseismic period preceding the 2011 Mw 9.0 Tohoku earthquake, in which direction did the eastern coastline of the main Japanese island of Honshu move?
Westwards and upwards (uplift).
Eastwards and downwards (subsidence).
Eastwards and upwards (uplift).
Northwards and downwards (subsidence).
66
Intraplate earthquakes in eastern Canada are mostly associated with which geological feature(s)?
The Canadian Shield.
Failed rifts and the North Atlantic passive margin.
Faults and folds of the Appalachian mountain belt.
The Sudbury and Manicouagan impact craters.
67
What is a postglacial earthquake?
An earthquake caused by bending stresses following the melting of ice sheets and glaciers.
Any earthquake that occurred during the Holocene (i.e., since the end of the last Ice Age).
A fracture caused by thawing of the ground surface following the melting of ice sheets and glaciers.
An earthquake caused by shearing stresses from the flow of glaciers over the Earth surface.
68
Which of the following statements about the Iranian capital city of Tehran is true?
Tehran was badly damaged in the 2003 Mw 6.6 Bam earthquake.
Fortunately, Tehran lies within an area of Iran that is not thought to be at risk from earthquakes.
Tehran has no historic record of earthquakes, but modern seismic instrumentation detects abundant seismicity there.
Tehran has experienced several large earthquakes in its recorded history, but none since it grew into a large metropolis.
69
Which of the following regions within Cascadia is most closely associated with intermediate depth "intraslab" earthquakes?
Northern Vancouver Island.
The Lower Mainland region of BC.
Southern Vancouver Island.
The Puget Sound region in Washington State.
70
Which of the following U.S. States is closely associated with induced seismicity?
Oklahoma.
California.
Florida.
Alaska.
Hawaii.
71
Along some parts of some faults, the two sides move past each other slowly, and continuously, without the stick-slip behaviour associated with earthquakes. What is the name given to this slow and steady fault motion?
Fault creep.
Poro-elastic rebound.
Visco-elastic relaxation.
Interseismic deformation.
72
Iran occupies the boundary zone between which two tectonic plates?
Africa and Eurasia.
Arabia and Africa.
Arabia and Eurasia.
India and Eurasia.
73
During the 2011 Mw 9.0 Tohoku earthquake, in which direction did the eastern coastline of the main Japanese island of Honshu move?
Eastwards and downwards (subsidence).
Northwards and upwards (uplift).
Westwards and downwards (subsidence).
Westwards and upwards (uplift).
74
MC - more case studies
75
What is the engineering term for decoupling/disconnecting a building from the ground, in order to reduce its vibration in an earthquake?
Base isolation.
Seismic retrofitting.
Surface wave reduction.
Resonance.
76
Complete the sentence: earthquake prediction is...
... currently impossible.
... currently possible, but only for earthquakes with foreshocks.
... currently possible, but only in certain parts of the world.
... currently possible, but only for the largest earthquakes.
77
'There is a ~12% to ~33% chance of a megathrust earthquake on the Cascadia subduction zone in the next fifty years.' This statement is an example of what?
An earthquake early warning.
An earthquake forecast.
A seismic retrofit.
An earthquake prediction.
78
What is the central aim of the U.S. Geological Survey's PAGER program?
To map damage in each major earthquake from across the United States using satellite radar measurements
To map damage in each major earthquake from around the world using satellite radar measurements
To issue to users (e.g. scientists, emergency responders) a rapid alert to each earthquake above a threshold magnitude of 3 from across the United States
To issue to users (e.g. scientists, emergency responders) a rapid alert to each earthquake above a threshold magnitude of 4 from around the world
To estimate very rapidly the damage (in terms of both fatalities and economic costs) caused by each major earthquake from across the United States
To estimate very rapidly the damage (in terms of both fatalities and economic costs) caused by each major earthquake from around the world
79
What phenomenon is shown in the photograph below?
Soft first storey collapse
Pancaking
Liquefaction damage
80
If the BC government built an earthquake early warning system on Vancouver Island, what would happen to the seismic hazard and seismic risk in Victoria?
The hazard would stay the same, but the risk would decrease.
The hazard would decrease, but the risk would stay the same.
Both the hazard and the risk would stay the same.
Both the hazard and the risk would decrease.
81
Which of these statements is true?
Immediately after a large earthquake, authorities and media often underestimate the number of fatalities compared to expert estimates.
Immediately after a large earthquake, authorities and media usually overestimate the number of fatalities compared to expert estimates.
Immediately after a large earthquake, authorities and media are highly accurate at estimating the number of fatalities.
82
In what way did damage to Mexico City differ between the 1985 Mw 8.0 Michoacán and 2017 Mw 7.1 Puebla earthquakes?
The Michoacán earthquake destroyed all of the oldest buildings in the city, so that the Puebla earthquake damaged only modern buildings.
Damage from the Puebla earthquake was greater, despite its smaller magnitude.
Damage from the Michoacán earthquake occurred mostly to larger buildings, whereas damage from the Puebla earthquake occurred mostly to smaller buildings.
83
Which continent has suffered the most fatalities from earthquakes?
Europe
Asia
South America
Africa
84
Soft first storey collapse is a common mode of building failure in earthquakes, because...
...many buildings are constructed to withstand vertical forces, but not strong horizontal accelerations.
...many buildings are built from masonry, rather than with stronger steel or wood frames.
...many buildings are constructed upon soft sediment that can liquify during ground shaking.
85
VOLCANOES
86
(a) Why is magma viscosity important in governing how explosive a volcanic eruption is?
(b) List the three main magma compositions in order of increasing viscosity (i.e., starting with the“runniest”).
87
(a) What is a pyroclastic flow, and in what ways can one form?
(b) Describe an example of a real eruption in which pyroclastic flows were a major hazard.
88
(a) In the 18th May 1980 Mount St. Helens eruption, what was responsible for the strong northward focus of the lateral blast, shockwave, and pyroclastic flows?
(b) In hindsight, which measurements taken before the eruption might have helped anticipate this pattern of damage?
89
(a) Why was the 2010 Eyjafjallaj ̈okull (Iceland) eruption not a typical Icelandic-style eruption?
(b) Briefly describe the human impacts of this event.
90
The schematic cross-section below depicts three tectonic settings in which volcanism occurs, labelled A, B & C. The black arrows show relative plate motions and the contours represent mantle temperatures.
(a) On the diagram, label A, B and C as either an oceanic hot spot, a mid-ocean ridge, or a volcanic arc.
(b) At which of these tectonic settings is volcanism least explosive, and at which is it most explosive?
(c) At which of these tectonic settings does the majority (∼80%) of Earth’s volcanism occur?
(d) At which of these tectonic settings do shield volcanoes form, and at which do strato volcanoes form?
(e) Why does melting occur at location D?
91
MC
92
What is a volcanic igneous rock (e.g. basalt, andesite, rhyolite)?
Rock made from magma that solidified below the surface.
Rock made from lava that solidified at the surface.
Rock formed from fall-out of airborne pyroclasts like ash.
93
Which of the following volcanic eruption styles is associated with flood basalts?
Stombolian-type.
Plinean-type.
Icelandic-type.
Vulcanian-type.
94
What accounts for the initial melting in a subduction zone beneath a volcanic arc?
Compression melting, as pressure increases as the subducting slab moves to greater depths in the mantle.
Release of water from subducted wet sediments and hydrated minerals.
Friction on the subduction megathrust fault.
Radioactivity in the mantle.
95
What type of volcano can be found in parts of central and northern British Columbia?
Cinder cones (or scoria cones).
Stratovolcanoes.
Shield volcanoes.
96
Which component of silicate minerals is responsible for raising the viscosity of magma (making it less runny)?
Magnesium sulfate (MgSO4).
Calcium carbonate (CaCO3).
Silica (SiO2).
Water (H2O).
Iron carbono-potassiumate (FeCK).
97
Which of the following volcanic eruption styles is associated with shield volcanoes?
Hawaiian-type.
Vulcanian-type.
Icelandic-type.
Stombolian-type.
Plinian-type.
98
What is the volcanic equivalent of granite?
Rhyolite.
Basalt.
Andesite.
Gabbro.
99
Which of the following types of volcano is smallest?
Cinder cones (or scoria cones).
Stratovolcanoes.
Shield volcanoes.
100
Vulcanian-type eruptions are associated with which type of volcanic landform?
Tall, gently-sloped shield volcanoes.
Small, steep cinder cones (or scoria cones).
Tall, steep stratovolcanoes.
Stacks of flat flood basalts.
101
When magma rises, and become less pressurized, what process occurs that is a key factor in driving explosive volcanism?
The magma becomes less viscous (more runny).
The magma becomes hotter, and therefore less dense, and more buoyant.
Dissolved volatiles come out of solution ("exsolution"), forming gas bubbles.
102
MC - case studies
103
Which of the following volcanic hazards was not responsible for fatalities in the 1980 Mount St. Helens eruption?
The lateral blast.
Lava flows.
Lahars.
Pyroclastic flows.
104
Which best summarizes the human impacts of the 2018 eruption of Kīlauea volcano, Hawai'i?
Trans-Pacific air travel was disrupted for many days by ash dispersed in the atmosphere.
Lava flows and volcanic bombs destroyed much property, but nobody was killed.
Several tourists were killed by volcanic blocks and bombs.
Lahars wiped out roads and bridges, completely cutting off communities in southern Hawai'i.
105
Order the following volcanic processes according to speed, starting with the slowest:
A’a lava flow < Lahar < Pyroclastic flow
Lahar < Pyroclastic flow < A’a lava flow
A’a lava flow < Pyroclastic flow < Lahar
Pyroclastic flow < A’a lava flow < Lahar
106
Limnic eruptions are mostly associated with which continent?
Africa
Asia
South America
North America
107
Which was the deadliest volcanic eruption in North American recorded history?
The 2018 eruption of Kīlauea, Hawai'i.
The 1980 eruption of Mount St. Helens, Washington.
The ~1700 CE eruption of Tseax Cone, BC.
108
Over the past 4,000 years, which has been the most active of the Cascade arc volcanoes?
Mount Rainier, Washington.
Mount St. Helens, Washington.
Mount Baker, Washington.
Lassen Peak, California.
Crater Lake, Oregon.
109
In the 1980 Mount St. Helens eruption, what was responsible for the strong northward directivity (lateral blast)?
A landslide collapsed the northern flank of the volcano.
The underlying subducting slab dips towards the North.
Prevailing winds from the South.
Intensive forestry in the North, which destabilized the Northern flank of the volcano.
110
In which of these eruptions did around 30,000 people die in a pyroclastic flow?
The 1902 eruption of Mount Pelée, Martinique.
The 1980 eruption of Mount St. Helens, USA.
The 1985 eruption of Nevado del Ruiz, Colombia.
The 1991 eruption of Mount Unzen, Japan.
The 1991 eruption of Mount Pinatubo, Philippines.
111
What is a limnic eruption?
A sudden overturn of deep lake waters that releases large volumes of dissolved volcanic gases.
An explosion caused by hot magma or lava coming into contact with ground water, surface water, snow or ice.
An eruption that is intermediary between a Strombolian-type eruption and a Vulcanian-type eruption.
The ejection of pressurized mud from a mud volcano.
112
How can volcanic eruptions often be anticipated in advance?
Earthquake swarms indicate moving magma at depth.
The volcano “bulges” due to rising magma, which can be observed at the surface.
Both of the above.
Neither of the above: volcanic eruptions can never be anticipated.
113
LANDSLIDES
114
Describe three ways in which water can increase the likelihood of landsliding, using case studies to illustrate where possible.
115
(a) Annotate the schematic illustration below with the following geomorphic features: (i) head scarp, (ii) transverse cracks, (iii) toe, (iv) basal failure surface.
Please be precise with any arrows drawn.
(b) What type of landslide is depicted?
116
(a) What was the most important precondition(s) and trigger(s) of the January 2018 Montecito, California mudflows?
(b) Why did many people choose not to evacuate Montecito on the night of the disaster, even when advised?
117
MC
118
Which of these types of landslide is normally slowest?
Soil creep.
Earth flow.
Rock stasis.
119
By what characteristics are landslides normally classified?
On the basis of the type of movement and the speed of movement.
On the basis of the type of movement.
On the basis of the type of material being moved.
On the basis of the type of material being moved and the style of movement.
On the basis of the speed of movement.
120
Which statement is true?
Mass movements are a subset of landslides.
Mass movements and landslides mean exactly the same thing.
Landslides are a subset of mass movements.
121
Why are clay minerals so slippery?
Water gets trapped between the silicate "sheet" layers, which slide past each other.
Clay minerals do not contain chemical bonds, so they dissolve easily in water.
Clay minerals contain Potassium (K), which is radioactive. Decay of K atoms breaks apart the mineral structure.
122
Which natural hazards are effective triggers of landslides?
Earthquakes.
Intense rainfall events (e.g. storms, hurricanes).
Both of the above.
123
Amongst the different types of landslides, what is unusual about lateral spread landslides?
They involve material moving out radially from the centre of the landslide.
They involve triggering by earthquakes.
They involve material falling into sinkholes.
They involve material moving down low-angle slopes of just 0.5-1º.
124
What is the category of composite landslide which starts as a rock fall and then becomes a debris slide?
Rock avalanche.
Rotational rock slide.
Lateral spread.
Mass movement.
125
What was the trigger for landslides that killed ~11,000 people in Honduras and Nicaragua in 1998?
A volcanic eruption.
A major earthquake.
A tornado.
A hurricane.
126
Why does steepening a slope reduce its stability (or increase its instability)?
The coefficient of friction on the slope is reduced.
Gravity is increased.
The component of gravity acting parallel to slope is increased, while the component acting perpendicular to slope is reduced.
The component of gravity acting parallel to slope is reduced, while the component acting perpendicular to slope is increased.
The coefficient of friction on the slope is increased.
127
Why are formerly-glaciated landscapes (including most of Canada) especially prone to landsliding?
Because glacial weathering left behind glacial till rich in clay minerals, which expand when wet and act as potential failure planes.
Because isostatic rebound raises the gravitational potential energy of these areas, so they are more prone to ground failures.
Because melting permafrost makes slopes weaker and the Northern latitudes are more susceptible to raising temperatures due to climate change.
Because these areas experience more winter precipitation (rain or snow), which will saturate the soil and promote landsliding.
128
MC - case studies
129
Which landslide disaster was likely made worse by "evacuation fatigue"?
The 2018 Montecito landslide.
The 2008 Wenchuan earthquake landslides.
The 2010 Mt Meager landslide.
The 2014 Oso landslide.
130
What is the purpose of an acoustic flow monitor and how does one work?
Early warning of rock falls from detecting the "crack" of the rock fracturing.
Early warning of rock slides from detecting air pressure waves.
Early warning of volcanic mass movements from detecting the shockwave of the initial explosion.
Early warning of debris flows or lahars from detecting the vibrations they produce.
131
There were many preconditions that led to the 2014 Oso (Washington) landslide, but what was the likely trigger?
Meandering of the Stillaguamish River undercut the hillslope.
A large earthquake caused heavy ground shaking.
A period of heavy rainfall preceding the landslide.
Deforestation due to logging weakened the hillslope.
132
Which broad region of Canada has the greatest landslide hazards?
Ontario and Quebec in Central Canada, because that’s where most Canadians live.
Western Canada (BC, Alberta, Yukon), because of its steep, mountainous terrain.
The Atlantic Maritime provinces of eastern Canada, because of their long, rocky coastline.
Northern Canada, because of melting permafrost.
133
In the weeks leading up to the 9th January 2018 Montecito mudslides, what weather systems affected coastal southern California?
A westerly cold weather front, followed by dry easterly Santa Ana winds.
Dry easterly Santa Ana winds, followed by a westerly cold weather front.
An easterly cold weather front, followed by dry westerly Santa Ana winds.
Dry westerly Santa Ana winds, followed by an easterly cold weather front.
134
Based on evidence from the 2010 Mt Meager landslide, roughly how long might a debris flow or lahar take to reach Pemberton from the base of the volcano? (The distance is ~65 km).
Nearly an hour.
Five hours.
Twenty five seconds.
Five minutes.
135
What is the most effective way to reduce the risk of rock falls along coastal sea cliffs?
Reducing erosion at the base of the cliff, such as with offshore breakwaters ("supporting the toe").
Removing material from the top of the cliff ("unloading the head").
Inserting horizontal rock bolts into the middle of the cliff ("reinforcing the body").
136
Why is Mt Meager especially prone to landsliding?
It lies on the active Lillooet fault which experiences frequent earthquakes.
It is an extremely active volcano that erupts every few decades.
Summer hikers cause significant erosion to trails, destabilizing the mountainsides.
It is made of volcanic rocks weakened through hydrothermal activity and steepened through glaciation.
137
In the 6th August 2010 Mt Meager landslide, how long did it take material to travel the 13 km from near the top of Mt Meager to the Lillooet River?
About one and a half minutes (90 seconds).
About five minutes (325 seconds)
Just ten seconds.
About thirty minutes.
138
The 2010 Mt Meager landslide is a good example of a composite landslide. What sequence of mass movements occurred?
Snow avalanche --> snow and debris flow
Rotational rock slide --> debris slide
Rock fall --> rock avalanche --> debris flow
Volcanic eruption --> pyroclastic flow --> lahar
139
TSUNAMIS
140
Why is a 5 m-high tsunami wave much more devastating than a 5 m-high wind wave at the coastline?
141
Explain in simple terms why megathrust earthquakes often produce ocean-wide tsunamis, while landslide-induced tsunamis normally affect only local or regional coastlines.
List one case study of each type of tsunami (provide the name of the event and the year).
142
What was unusual about the 28th September 2018 Palu (Sulawesi) tsunami?
List three possible mechanisms for how the wave was generated.
143
(a) What sequence of geological events triggered the 18th November 1929 Grand Banks tsunami, and how was it discovered?
(b) How did these triggers differ from those of the 9th July 1958 Lituya Bay tsunami?
Briefly, compare and contrast the human impacts of these two tsunamis.
144
MC
145
Tsunami waves are preceded by a period of sea-level drawback, in which sea water is seen to retreat from beaches...
...some of the time (i.e. this occurs about half of the time).
...none of the time (i.e. this is an urban myth).
...always (i.e. this occurs before every tsunami wave arriving at a coastline).
146
What is a "seiche"?
Periodic “sloshing” of water back and forth across an enclosed basin such as a lake or fjord.
A tsunami wave generated in the ocean which travels up a river valley.
An atmospheric phenomenon, causing strong winds.
An underwater current of sediment-laden water moving rapidly down slope.
147
Which of these tsunami sources is most likely to generate an ocean-wide tsunami?
Megathrust earthquakes, submarine landslides and submarine volcanic eruptions are equally likely to generate an ocean-wide tsunami.
Submarine volcanic eruptions.
Submarine landslides.
Megathrust earthquakes.
148
What happens to tsunami waves when they pass from deep water into shallow water?
They accelerate and diminish in height.
They stay the same speed, but grow larger in height.
The accelerate and stay the same height.
They slow down due to friction on the sea floor, but grow larger in height.
149
What is a meteotsunami?
Any medium-sized tsunami wave.
A tsunami or seiche wave caused by atmospheric conditions, such as strong winds.
A tsunami or seiche wave caused by a meteorite impact.
150
Roughly how long do tsunami waves generated on one side of the Pacific Ocean take to travel to the other side, ~10,000 km away?
~10 days: the tsunami travels across the deep ocean at about the same speed as a car.
~10 minutes: the tsunami travels across the deep ocean at about the same speed as seismic waves.
~10 hours: the tsunami travels across the deep ocean at about the same speed as a commercial airliner.
151
Where does the word "tsunami" originate?
From the Hawaiian for "watery death".
From the Japanese for "harbour wave", because fishermen would go out to sea, notice nothing unusual, but then come home to find their harbours destroyed.
From the Japanese for "tidal wave", since tsunamis are associated with tidal forces.
152
What is the common cause of seiches in the Great Lakes (e.g. Lake Erie)?
Rock falls along steep sections of the lakes’ shorelines.
Local intraplate earthquakes.
Strong and persistent westerly winds.
Ocean tsunami waves that migrate up the St Lawrence River.
153
What causes focusing and defocusing of tsunami waves crossing the deep ocean?
Variations in water depth due to bathymetry (sea-floor topography).
Ocean currents.
Changes in atmospheric pressure and wind direction.
Rotation of the Earth (the "Coriolis effect").
154
In the simplest of terms, why are tsunami waves more dangerous than wind waves?
Their greater height (amplitude).
Their longer wavelength and greater momentum.
Their greater velocity.
155
MC - case studies
156
What triggered the 2017 Nuugaatsiaq (West Greenland) tsunami?
A local earthquake.
Collapse of part of the Greenland Ice Sheet.
A debris flow.
A coastal rock avalanche.
A distant megathrust earthquake.
157
What tsunami hazard monitoring system(s) are being implemented around Vancouver Island?
A shore-based radar system at Tofino detects strong currents associated with incoming tsunami waves.
An offshore fiber-optic cabled observatory of ocean bottom pressure sensors detects the excess weight of incoming tsunami waves.
Both of the above.
None of the above. These systems are being implemented elsewhere, but not around Vancouver Island.
158
Why were tsunami waves from the 11th March 2011 Tohoku (Japan) earthquake much higher in some coastal towns (e.g. Miyako) than in neighbouring towns the same distance from the tsunami source (e.g. Sendai)?
Because the wind direction at the time of the tsunami pushed the waves northwards.
This effect is poorly understood, and appears to be due to random chance.
Because the shape of the coastline funnelled more of the wave energy into coastal gulfs and inlets.
159
How is the hazard cascade that resulted in the 1929 Grand Banks tsunami best characterized?
An earthquake triggered a submarine landslide that generated the tsunami.
An offshore earthquake generated the tsunami.
A coastal rock slide generated the tsunami.
A submarine landslide generated the tsunami.
An earthquake triggered a coastal rock slide that generated the tsunami.
160
Which of the following can be ruled out from being a possible cause of the 2018 Palu, Indonesia tsunami.
A subduction zone megathrust earthquake.
A shallow crustal earthquake.
Earthquake-triggered landsliding.
161
Which of the following types of water wave should be of concern to British Columbians?
Seiche waves like those following the 1959 Hebgen Lake earthquake.
Tsunami waves from Cascadia megathrust earthquakes like the AD 1700 earthquake.
Tsunami waves from distant megathrust earthquakes like the 2011 Tohoku-oki earthquake.
Tsunami waves triggered by landslides like in the 1958 Lituya Bay tsunami.
All of the above.
162
Which country frequently affected by tsunamis has invested heavily in sea wall defences?
Canada
New Zealand
USA
Indonesia
Japan
163
In the 1958 Lituya Bay tsunami, what was the approximate maximum local wave height?
5 meters.
50 meters.
500 meters.
5 kilometers.
164
Anthropogenic global warming may have contributed towards the 2017 Nuugaatsiaq tsunami — but how?
Global warming has resulted in less sea ice in western Greenland, subjecting the shores of Karrat Fjord to increased wave erosion.
Global warming has resulted in more intense rainfall in western Greenland, a major factor in generating the landslide responsible for the 2017 tsunami.
Global warming has accelerated glacial retreat at the end of Karrat Fjord, debuttressing its slopes. Permafrost melting may have further weakened these slopes.
Melting of the Greenland ice sheet has raised sea-level, increasing the tsunami hazard for coastal communities like Nuugaatsiaq.
165
How is the hazard cascade that resulted in the 1958 Lituya Bay tsunami best characterized?
A coastal rock slide generated the tsunami.
An earthquake triggered a coastal rock slide that generated the tsunami.
An offshore earthquake generated the tsunami.
An earthquake triggered a submarine landslide that generated the tsunami.
A submarine landslide generated the tsunami.
166
WEATHER & CLIMATE HAZARDS
167
(a) Seven of nine of the deadliest weather events in the 20th Century were in Bangladesh.
What type of events were these? Describe why they were so devastating.
(b) Are the frequencies and risks of these events likely to increase or decrease in the next several decades?
168
List and describe five separate mechanisms by which hurricanes kill and injure people and destroy infrastructure.
169
Name and describe the most common type of flooding in Canada, how it develops, and relevant characteristics.
170
What aspect(s) of the 2005 Hurricane Katrina were most devastating to the city of New Orleans?
What were the human impacts of this disaster, and what could have been done differently/better to reduce such impacts?
171
With reference to the geography of North America, explain where tornadoes typically form and briefly explain why this is so.
172
Name four different forest wildfire suppression techniques, and what portion of the “fire triangle” they remove from the fire.
173
What factors made the 2016 Fort McMurray wild fire so devastating?
174
MC
175
What pattern of atmospheric convection occurs within the Hadley cell?
Air rises at Mid-latitudes (30º) and sinks at the Equator (0º)
Air rises at High-latitudes (60º) and sinks at the Poles (90º)
Air rises at Mid-latitudes (30º) and sinks at High-latitudes (60º)
Air rises at the Equator (0º) and sinks at Mid-latitudes (30º)
176
Why are hurricanes becoming more impactful due to anthropogenic global warming?
Warmer ocean surface temperatures increase evaporation, feeding larger and more intense tropical storms.
Sea-level rise is increasing the land area at risk from storm surges.
Both of the above.
Neither of the above – in contrast with other weather hazards, hurricane impacts are not increasing.
177
Why are tornadoes so prevalent in the American Midwest?
Because tornadoes require warm air temperatures, and this region experiences the warmest summers in North America.
Because tornadoes require flat topography, and this is the flattest region in North America.
Because tornadoes require atmospheric instabilities, and several distinct air masses converge in this region.
178
According to which scale are tropical cyclones classified?
The moment magnitude scale.
The Saffir-Simpson scale.
The Mercalli intensity scale.
The Fujita scale.
179
Which type of tropical cyclone is most common?
Hurricanes in the North Atlantic and NE Pacific
Typhoons in the West Pacific
Cyclones in the Indian Ocean
180
Why don't tropical cyclones occur at the Equator?
There is insufficient atmospheric disturbance here, because of the weak Coriolis effect.
The water is too warm; tropical cyclones require water at intermediate temperatures.
Air at the Equator descends, whereas tropical cyclones require the air to rise.
181
Which hazard associated with tropical cyclones has caused the greatest number of fatalities, globally?
Flooding from heavy rainfall
High wind speeds
Landsliding
Storm surges
182
According to which scale are tornadoes classified?
The Fujita scale
The Saffir-Simpson scale
The Mercalli intensity scale
The moment magnitude scale
183
What rise in global average sea-level do current climate models forecast happening this century (i.e. by 2100)?
Between 12 cm and 30 cm
Between 120 cm and 300 cm
Between 3 cm and 12 cm
Between 30 cm and 120 cm
184
What are the prevailing wind directions at Mid-latitudes (~30º–40º North or South)?
Westerly winds in the northern hemisphere and easterly winds in the southern hemisphere
Easterly winds in the northern hemisphere and westerly winds in the southern hemisphere
Westerly winds (i.e. blowing from west to east) in both hemispheres
Easterly winds (i.e. blowing from east to west) in both hemispheres
185
MC - case studies
186
What is a jökulhlaup?
An outburst flood from a glacier.
A flood caused by a landslide.
Another name for a glacial erratic (boulder dropped by glaciers).
A volcano in Iceland with a glacier on top.
187
Hydro-meteorological floods are caused by:
Rainfall
Snowmelt
Ice jams
All of the above
188
When a flash flood submerges a road, what level of water is required to move an average-sized car laterally?
10 centimeters
60 centimeters
30 centimeters
1 meter
189
What is the main reason behind the rapid growth in reported number of floods in Canada over the past few decades?
More intense run-off due to the effects of deforestation and wildfires
More and more people living in flood-prone areas
Heavier rainfall due to warmer sea-surface temperatures
More concentrated snowmelt due to global warming
190
What is the definition of a 100-year floodplain?
An area which last flooded 100 years ago
An area which is flooded once every 100 years.
An area with a 1% chance of flooding in any year.
An area with a 100% chance of flooding in any century.
191
Flash floods involve torrential rainfall over what time period?
<6 hours
<12 hours
<1 hour
>24 hours
192
At what time of year does flooding peak in Canada?
Spring (March, April, May)
Summer (June, July, August)
Fall (September, October, November)
Winter (December, January, February)
193
Outburst floods are caused by:
Intense local precipitation.
Sustained rainfall, often from hurricanes.
Catastrophic failure of natural dams.
Structural failure of man-made infrastructure.
194
Where can ice jams cause flooding?
Both upstream and downstream of the ice jam
Upstream of the ice jam
Downstream of the ice jam
195
People are drawn to building and living on floodplains for the reason of:
Safety from landslides.
Fertile land for farming.
Inexpensive real estate.
Easier transportation.
196
197
