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ERTH 2415 > Lectures 1 - 10 > Flashcards

Lectures 1 - 10 Flashcards

1
Q

define natural disaster

A

large amount of energy released in a short time, with consequences for life and infrastructure

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2
Q

give a example of a natural hazard

A

unstable rock on mountain slope

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3
Q

spring and fall there are heavy rains. give the frequency and return period of heavy rains a year

A

frequency = 2 per year

return period = 1 every 6 months

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4
Q

give the 4 sources of energy

A

earth’s internal energy,
solar energy,
gravity,
impact energy,

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5
Q

list the 4 global trends

A

–disasters are increasing over time

–fatalities are increasing over time

–human made disasters been decreasing

– economic loss is increasing

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6
Q

list the 3 Canadian trends

A

–natural disasters increasing with time

–fatalities are decreasing

–economic losses are due to weather-related disasters

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7
Q

define risk

A

risk = vulnerability * Hazard

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8
Q

what are the 4 pillars of emergency management

A

–Response

–Recovery

–Mitigation

–prepardness

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9
Q

what is the term for : “middle-term activites to put the situation back to normal”

A

recovery

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10
Q

what is mitigation

A

Long term actions to eliminate risk… addresses the root cause of the problem

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11
Q

define preparedness

A

planning for disasters by putting in place resources to cope with the problem when it occurs

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12
Q

define adaptation

A

gradual adjustments to reduce harm

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13
Q

who is the father of plate tectonics

A

J. Tuzo Wilson

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14
Q

how does the solar nebula constrain planets?

A

make planets move in the same direction as the disk

orbits on the same plane

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15
Q

what is differentiation?

A

a process by which gravity causes denser material to gradually migrate to the center of the planet

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16
Q

list the elements that make up the following Crust, Mantle, Outer core, Inner Core

A

Crust : silicon and oxygen
Mantle: Iron and magnesium
Outer core: Liquid Iron
Inner core: solid Iron

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17
Q

what is the difference between oceanic crust and continental crust?

A

oceanic = more dense, and thin

continental = less dense, and thick

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18
Q

what are the strength of the following layers?
lithosphere
asthenosphere
mesophere

A 
lithosphere = Rigid
asthenosphere = soft plastic
mesophere = stiff plastic
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19
Q

what layer are tectonic plates

A

lithosphereic floating on asthenosphere

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20
Q

whats the lithosphere/asthenosphere depth boundary

A

100km

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21
Q

how do tectonic plates move?

A

they move due to convection cells

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22
Q

how long is a tectonic cycle?

A

250 Ma

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23
Q

what is subduction

A

process in which a lithospheric plate descends beneath another

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24
Q

what is bathymetry

A

depth measurements at various places in water

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25
Q

where do shallow earthquakes happen

A

overriding and subducting plate.

deep earthquakes in subducting plate only

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26
Q

what dominant force is at divergent zone?

A

tension

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27
Q

what dominant force is at convergent zone

A

compression

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28
Q

what dominant is at transform fault

A

shear

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29
Q

where do 80% of earthquakes and 75% of active volcanoes lie?

A

pacific plate

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30
Q

where is Ottawa location

A

center of North American plate

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31
Q

at what depth do hypocenters stop?

A

700 km because material in mesosphere is soft

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32
Q

list for the 4 steps to a new oceanic lithosphere

A

Centering: lithosphere centers over hot region

doming: lithosphere bulge up into a dome
rifting: area is pulled-apart by tension
spreading: new lithosphere is formed in pulled-apart area

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33
Q

what types of earthquakes are at the subduction zone ~30 km

A

Megathrust - due to shear stress

crustal earthquakes - due to compression

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34
Q

what types of earthquakes are at the subduction zone > 100 km

A

intra-slab earthquake, due to cold rock being consumed into hot asthenosphere

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35
Q

what are the two plates involved with the Cascadia megathrust

A

North American plate (overriding)

Juan de fuca plate (subducting)

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36
Q

which type of faults cause infrequent, major, shallow earthquake

A

transform faults (shear force)

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37
Q

what is a fault

A

fracture across which two blocks move relative to each other

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38
Q

positive or negative correlation between rupture length and magnitude

A

positive

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39
Q

define the following:

  • -seismometer
  • -seismograph
  • -seismogram
A

seismometer – sensor that detects ground motion

seismograph – instrument that records ground motions

seismogram – paper record or digital file with data describing ground motions

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40
Q

what are the frequency of body waves? of surface waves?

A

body > 1 hz

surface < 1 hz

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41
Q

what is the sideways motion from?

A

S waves (shear energy)

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42
Q

define intensity

A

measure of the effects of an earthquake on people and infrastructure

43
Q

what does Mercalli intensity scale measure

A

eye witness accounts,

damage to infrastructure

44
Q

generated automatically in real time.

A

shakemap

45
Q

what is a Felt area

A

area of the perceptible earthquake ground motion

46
Q

is size of the felt area a good indicator of magnitude?

A

NOPE

47
Q

what are the depths of megathrust earthquake hypocenter?

A

Shallow (~30km)

48
Q

how can you tell if a earthquake is a aftershock or a new earthquake?

A

mainshocks and aftershock have the same hypocenter

49
Q

the top ? Meters of rocks and soils have a major impact of ground motion

A

30

50
Q

what is natural frequency of soils? hard rocks?

A

soils < 1 Hz

hard rock > 1 Hz

51
Q

what is resonance?

A

system experiences very large oscillations when disturbed by a force function of frequency equal to its natural frequency

52
Q

whats the Hz of body waves? Surface waves?

A

body waves > 1 Hz = hard rock

surface waves < 1 Hz = soils

53
Q

where does liquefaction occur?

A

saturated soils, where space between particles are filled with water.

54
Q

whats better for earthquakes wood or masonry and why?

A

wood, cause higher elastic limit

55
Q

how do you calculate natural frequency

A

10 hz / number of stories

56
Q

what can we predict about earthquakes

A
  • -how much ground shaking there will be

- -where earthquakes are likely to occur

57
Q

what magnitude of earthquakes cause a Tsunami

A

7.5

58
Q

what causes a tsunami

A

vertical motion of rocks

59
Q

when does shoaling occur

A

hen depth < WaveLenght / 2

60
Q

how many meters water of wavelengths are wind caused waves confined to

A

first 100 meters

61
Q

how long are Tsunami waves

A

~100 km, always interacting with the sea floor

62
Q

what caused the indian ocean tsunami to be so destructive

A

lack of awareness also was caused by a megathrust earthquake. with a vertical slip of 10 m

63
Q

what caused the Japan earthquake and tsunami to be deadly?

A

height of waves underestimated

64
Q

what earthquake triggered a tsunami by landslide?

A

grand banks earthquake

65
Q

where are hazards the highest in canada?

A

BC due to earthquakes

66
Q

which rocks form by cooling and solidfication from hot molten rock material

A

igneous

67
Q

whats the difference intrusive and extrusive igneous rocks

A
  • intrusive: (cooling at depth) slow, large grains
  • extrusive: (cooling at surface)
    fast cooling, small grains
68
Q

igneous cooling: pale rocks mean ?

A

high SiO2 content (above 65)`

69
Q

what are the 3 factors that control viscosity?

A

1) SiO2 (higher Si02 content higher viscosity)
2) temperature (lower temp higher viscosity)
3) # of solids (more solids, higher viscosity)

70
Q

give an example of low viscosity magma

A

basltic

71
Q

give an example of high viscosity magma

A

rhyolitic

72
Q

whats the main volatile from a volcano

A

H20

73
Q

give the measurements of

Ash,
Lapilli,
Scoria,

A

Ash < 2mm

Lapilli 2-64 mm

Scoria > 64 mm

74
Q

what are the difference between bombs and blocks?

A

bombs: are semi-molten fragments when airborne.
blocks: are ejected as solid fragments

75
Q

what are the four tectonic environments

A

`1) divergent zone

2) convergent zone
a) subduction zone
b) continent-continent collision zone
3) transform fault
4) hotspot

76
Q

what are the four tectonic environments with volcanic activity

A

1) divergent zone
2) convergent zone
a) subduction zone
3) hot spot

77
Q

in general list whether the following are peaceful, explosive or both.

  • divergent zones
  • subduction zones
  • hot spots
A
  • divergent zones = peaceful
  • subduction zones = explosive
  • hot spots = both
78
Q

what is the role of water for volcanoes at subduction zones?

A

water lowers the melting point of rock and allows magma to rise through overriding plate

79
Q

what provides more SiO2 enrichment? Oceanic-Continental or Oceanic-Oceanic

A

Oceanic-Continental

80
Q

how are hotspots aligned? can call the age of a hot spot?

A

with the direction of plate motion.. age increases with distance of hot spot

81
Q

hotspots, if rising magma mixes with thick continental crust it will be what type of explosion? thin

A

thick crust = explosive

thin crust = peaceful

82
Q

list the steps of a volcanic eruption

A

1) solid rock rises closer to surface (due to convection loop) this causes decompression melting
2) more rocks liquify causing volume expansion
3) gas (volatiles) come out of melt
4) when bubbles reach >= 75% of magma volume gas jet expels magma in atmosphere

83
Q

what are the three Vs of volcanism

A

1) Viscosity
2) Volatiles
3) Volume of magma

84
Q

describe the 3 Vs of icelandic-type eruptions and what landform does it create?

A

Viscosity = Low
Volatile Content = easily escaped
Volume = small

lava plateau

85
Q

what tectonic environments do you find: hawaiian-type eruptions and Icelandic-type eruptions

A

Divergent zones and Hot spots

86
Q

what are the 3 Vs of Hawaiian-type eruptions? and what landform does it create?

A

Viscosity = Low
Volatile content = Low
Volume = Large

Shield volcano

87
Q

whats the difference between a lava plateau and shield volcano?

A

shield volcano is larger,
shield volcano is a shape of a dome while lava plateau is flat.
shield volcano has a Surface rupture

88
Q

what are the 3 Vs of Strombolian-type eruptions?

and the landform it creates

A

Viscosity = medium
Volatile content = medium
Volume = small

Scora cone

89
Q

Scoria ccone is typically a monogenetic volcano. what does this mean

A

its eruptive phase is a few years.. and it doesn’t erupt again

90
Q

what are the 3 Vs of a Vulcanian-type eruption? and the landform it creates

A

Viscosity = medium
Volatile content = Medium
Volume = Large

stratovolcano

91
Q

what do Plinian-type eruptions normally follow?

A

Vulcanian-type

92
Q

whats the main difference between Philnian-type and Vulcanian-type eruptions

A

height of eruption

93
Q

During main phase what re the 3 Vs of Philnian-type eruptions

A

Viscosity = Medium
Volatile Content = High
Volume = Large

94
Q

During final phase what re the 3 Vs of Philnian-type eruptions

and what is the landform?

A

Viscosity = High
Volatile content = Low
Volume = Small

lava dome

95
Q

what are the details of a lavadom

A

volcanic cone with a highly viscous blob of lava forming over a half-ball over the vent

96
Q

what are the 3 Vs of a ERTH2415

Eruptive style and landforms Caldera-type eruption?

A 
Viscosity = High
Volatile = High
Volume = High
97
Q

what type of eruptions are the largest?

A

Caldera-type eruption

98
Q

list the steps of a typical explosive eruptive sequence.

A

early phase: vulcanian-type eruption thus formation of a stratovolcano

major phase: Plinian-type eurption, continued development of a stratovolcano

final phase: Plinian-type eruption (lava dome) OR caldera type eruption (caldera)

99
Q

what are Canadian volcanoes associated with?

A

curstal rifting

100
Q

what is responsible for the largest number of fatalities related to volcanism

A

Pyroclastic flow (hot gases and ash and rock moving down volcano)

101
Q

what is Lahar

A

mudflow that originates on the slopes of volcanoes when volcanic ash and debries become saturated with water

102
Q

where does lahar occur

A

almost always on stratovolcanoes

103
Q

why is mitigation hard for volcaones?

A

low frequency, high magnitude

difficult to predict

104
Q

what are the three factors of the VEI

A

volume of material extruded
height of eruption
duration of eruption

ERTH 2415 (6 decks)

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