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tect 2 (undone!!) Flashcards

1
Q

Define earthquake

A

LINK
Litosphere: Uppermost mantle, Plate

Answer
- Shaking of earth’s ground due to sudden release of energy from litosphere

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2
Q

Where do earthquakes generally occur at?

A

Along plate boundaries which have a system of faults

All plate boundaries have faults.

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3
Q

How does earthquakes form? (4 points)

A
  1. Rock masses on either side of fault pushed by [tectonic force]
  2. Friction causes plates to get locked, stress builds up
  3. When stress exceeds strength of [rock/ fault], rocks [snap/suddenly move to] another position
  4. causes seismic waves release, result in ground shaking
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4
Q

What are faults?

A

A system of deep fractures

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5
Q

What is a focus?

A

the place inside Earth’s crust where earthquake originates

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6
Q

where is the origin of an earthquake?

A

focus

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7
Q

what is the epicenter?

A

the point on earth’s surface directly above focus

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8
Q

where is shaking most strongly felt?

A

near the epicenter

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9
Q

how are earthquakes measured?

A

seisometers

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10
Q

how do the equipment to measure earthquake work?

A

LINK
Seisometer
ANS
sensitive instruments detect ground vibrations, determine magnitude

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11
Q

Increasing what will incrase the magnitude of earthquake?

A

Increasing the seismic energy released

LINK
Earthquake occur when seismic waves are released

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12
Q

Which scales do scientists use to rate magnitude of earthquake?

A
  • ML (richter scale)
  • Mw (Moment magnitude Scale)
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13
Q

How does Richter Scale calculate earthquake magnitude?

A
  • height of largest wave recorded on seismometer
  • based on maximum seismic intensity reached
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14
Q

Richter Scale’s characteristics

A
  • Numbered from 1-10
  • Logarithmic
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15
Q

What does a logarithmic scale mean?

A

Earthquake of Mw/ML 2 is 32 times greater than Mw/ML 1

LINK
- Mw Scale: Moment Magnitude Scale
- ML Scale: Richter Scale

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16
Q

What are the limitations of Richter Scale?

A
  • underestimates longer earthquakes that release more overall energy
  • rate an earthquake with 1 single drastic spike larger than earthquake with many large waves as higher
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17
Q

Is the richter scale commonly used?

A

No
- small, local earthquakes only

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18
Q

How does the Moment Magnitude Scale rate earthquakes?

A
  • total energy released during earthquake
  • estimates total energy released
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19
Q

Which scale is more accurate? Richter or Moment Magnitude?

A

Moment Magnitude (Mw) generally more accurate

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20
Q

Characteristics of Mw Scale

A
  • Logarithmic
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21
Q

Example of Mw Scale being used

A
  • Prince William Sound Earthquake readjusted from Richter scale to Mw Scale (more accurate)
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22
Q

What is magnitude?

A

Measuring amount of seismic energy

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23
Q

How are volcanoes created?

A

When lava erupts onto Earth’s surface cools, forming cone-shaped mountain

(By God, btw!)

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24
Q

Which plate boundaries do volcanic eruptions occur?

A
  • Divergent
  • Convergent

Only at these boundaries do volcanoes form

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25
Q

How does volcano form at divergent plate boundaries?

5 parts

A
  1. Plates diverge
  2. Crust stretches, fractures develop
  3. Decreased overlying pressure causes underlying mantle, melt -> magma -> rises in weak areas of crust
  4. erupts as lava (volcanic eruption)
  5. cools, solidifies, accumulates over time, form volcano

Lava is magma on the surface

By God.

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26
Q

How does volcanoes form in o-c, o-o convergent plate boundaries?

7 parts

A
  1. Plates converge
  2. Denser plate subducts under less dense plate
  3. High pressure forces water out of O crust
  4. Water lowers melting pt of overlying mantle, causing it to melt -> magma
  5. Magma contains dissolved gases, less dense than surrounding materials, hence rises thru weak areas in crust
  6. Erupts as lava (volcanic eruption)
  7. lava cools, solidifies, accumulates over time, forms volcanoes

c-c convergence has no volcanoes forming

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27
Q

4 characteristics

How does High Silica Magma cause a violent, explosive explosion?

A
  1. More viscous
  2. As magma rises -> surface, dissolved gases in magma cannot escape easily
  3. More pressure builds up -> gases escape explosively
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28
Q

Is high silica magma in stratovolcanoes or shield volcanoes?

A

BOTH
- More associated with stratovolcanoes

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29
Q

How does low silica magma lead to gentle, e___ explosions?

A
  1. Less viscous magma
  2. Magma rises to surface -> dissolved gases escape easily
  3. Less pressure builds up -> gentle, effusive explosions
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30
Q

What is viscous?

A

Thick, sticky consistency

Just imagine the thick, sticky magma. Gases would obviously find it harder to escape through thicker and sticker magma

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31
Q

what is effusive eruption characterized by? (4)

A
  • gentle
  • mainly lava outpouring into ground
  • no tephra ejected
  • non-explosive
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32
Q

Is low silica magma in stratovolcanoes or shield volcanoes?

A

BOTH
- More associated with shield volcanoes

Shield = defensive
Therefore strato = offensive

“Defensive Volcano” will eject a gentler, effusive eruption

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33
Q

How do stratovolcanoes form? (4 points)

A
  1. High viscosity magma, rises thru weak areas in crust -> Earth’s surface, erupts explosively as lava, ash, rocks
  2. Ash, rocks settle on sides of volcano, later covered by lava
  3. After successive eruptions, tall volcano consist of alternating lava, ash layer develop
  4. Highly viscous lava travels shorter distance before cools, solidifies -> volcano has steep sides, narrow summit

o3o pattern does not equal to made smhh

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34
Q

How does shield volcanoes form?

A
  1. Low viscosity magma rises thru weak areas in crust -> Earth’s surface, erupts effusively
  2. After successive eruptions, volcano consisting of layers of lava develops
  3. Less viscous lava travels longer distance before cools, solidifies, volcano has gently sloping sides, broad summit
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35
Q

How is volcano intensity measured?

A

Volcanic Explosivity Index scale

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36
Q

What does VEI scale base itself on?

A
  • Vol. of ejected material
  • Height of eruption cloud
  • Duration of eruption
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37
Q

VEI scale characteristics

A
  • Measured on scale of 0-8
  • Effusive eruptions given value of 0-1
  • 8 = mega colossal explosive eruption
  • Logarithmic scale
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38
Q

Recap from Tect.1: What is logarithmic scale?

A

Increase of “1” in scale = 10 times more powerful than prev. no

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39
Q

Numbers! Numbers! Numbers!

Amount of material ejected from effusive eruption VS mega-colossal explosive eruption tephra and eruption cloud

A

effusive
- <0.0001km^3 material ejected
mega-colossal (VEI > 8)
- >1000km^3 tephra
- >25km eruption cloud column

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40
Q

What is tephra

A
  • any type/size rock fragment
  • forcefully ejected
  • travel airborne path (during eruption)
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41
Q

What is volcanic cone

A

triangle-shaped hill/mountain formed as lava accumulates around vent

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42
Q

What is magma chamber

A

Location in Earth’s crust where magma located

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43
Q

what is crater

A

Bowl-shaped depression at top of volcano

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44
Q

what is lava

A

molten rocks erupted onto Earth’s surface

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45
Q

what is conduit?

A

central passageway in volcano which magma travels through

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46
Q

3 statuses of volcano

A
  • active (erupt recently, likely erupt again)
  • dormant (erupt in last 2000 yrs)
  • extinct (no evidence of eruption in historic times, no evidence of magma reservior
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47
Q

what is magma

A

molten rocks found below Earth’s surface

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48
Q

what is active vent

A

opening on Earth’s surface through which lava erupts, situated at bottom of crater

49
Q

What boundaries do earthquakes occur along? How does earthquakes occur at plate boundaries?

A

all
plates are pushed by tectonic forces -> stress builds up -> energy eventually released

50
Q

do earthquakes only occur along plate boundaries?

List the rough quantity of earthquakes along 1 specific transform, convergent, and divergent boundary

A

no.
- Eurasian Plate
- Broad belt of earthquakes along convergent plate boundaries of PROF
- Narrow belt of earthquakes along divergent plate boundary of Mid-Alantic Ridge
- Narrow belt of earthquakes along transform plate boundary of San Andreas Fault

51
Q

Give specific examples.

Where is the largest concentration of earthquakes in?

A

Pacific Ring of Fire

52
Q

Which, out of the 3 plate boundaries do earthquakes occur more commonly in?

A

Convergent
More stress built up during subduction

53
Q

What is the Pacific Ring of Fire?

A

Broad belt around Pacific Ocean where most earthquakes, active volcanoes occur

54
Q

Which plate boundaries does the Pacific Ring of Fire contain?

A
  • Convergent: Pacific + Phillippine
  • Divergent: Pacific + Cocos
  • Transform: Pacific + North American

refer to plate tectonic map for clearer view

55
Q

Where are volcanoes generally found?

Example of quantity of volcanoes found in these boundaries

A

Convergent (except C-C convergence) + divergent boundaries

Convergence
- Belt of volcanoes along Pacific Ring of Fire’s convergent plate boundaries’ subduction zones

Divergence
- Belt of volcanoes along divergent plate boundaries between NA and Eurasian Plates

56
Q

Any volcanoes at transform plate boundary?

A

No
- Magma does not rise to Earth’s surface to form volcanoes

57
Q

What are hot spot volcanoes?

A

Volcanoes that develop over into hot regions in mantle
- May develop in locations away from plate boundaries

58
Q

General hazards of earthquakes

A
  • Ground shaking
  • Soil liquefaction
  • Landslides
  • Tsunamis
59
Q

General hazards of volcanic eruption

A
  • Tephra
  • Volcanic gases
  • Lava flows
  • Pyroclastic flows
  • Lahars
  • Volcanic landslides
60
Q

What is distribution?

A

Way that something is spread out/arranged over geographic area

61
Q

What is a secondary cone? When does it form?

A

Small volcano formed on side of main volcano

forms when:
1. pressure builds up

62
Q

What is soil liquefaction?

A

Phenomena where saturated, lose soil loses it’s structure -> transforms into thick fluid (due to ground shaking)

63
Q

Which boundaries do strato and shield volcanoes mainly lie on?

A

Strato: Converging
Shield: Diverging

64
Q

What is pyroclastic flow

A

Hot clouds of gas, ash, rocks travelling down slopes of volcano at >200km/h

65
Q

What is lahars?

A

Mudflows, comprising -> volcanic ash + water

66
Q

What is tsunami?

A

Series of ocean waves

67
Q

High silica magma = increased rate of flow.

Is this true?

A

no.

High silica = increased visocity = thicker = slower flow rate

68
Q

Characteristics of earthquake hazards

A
  • soil liquefaction, ground shaking, landslides usually localized
  • found near plate boundaries
  • tsunamis not located near epicenter (can travel thousands of kilometers from pt. of origin)
69
Q

Characteristics of volcanic eruption

A
  • volcanic gases, lava flows, pyroclastic flows, lahars, volcanic landslides localised
  • volcanic ash unlocalised
  • Volcanic ash can travel thousands of kilometers

Tephra is ambiguous as some is too heavy to travel far. some are quite small and have the potential to travel far away

70
Q

is ash always localised/spread away from the eruption?

A

no
dispersal of ash depends on
- wind conditions
- volume of ash erupted
- height of ash thrown into atmosphere

71
Q

What is geothermal energy?

A
  • energy derived from heat in Earth’s crust
72
Q

what is weathering

A

breaking down/dissolving of rocks on Earth’s surface

73
Q

How does all earthquake/tsunami/volcano hazards affect natural and human systems? (4 points)

A
  • Destroys ecosystems
  • Destroys properties, infastructure
  • Disrupts human systems
  • Causes fatalities, injuries

tsunami isnt undersea earthquake. Not all of them are triggered by it

Not all have all four.

e.g. volcanic gses only has destroy ecosystem, properties, cause fatalities

74
Q

How does ground shaking destroy ecosystems?

A
  • ruptures chemical factories -> pollution
  • fractures, uproot trees
75
Q

how does ground shaking destroy properties and infastructure?

A

Weaken roads, buildings -> collapse -> difficult to rescue people/supply aid

76
Q

How does ground shaking disrupt human services?

A
  • snap waterpipes, result in water shortages
  • snap communication+electricity cables, affect important comm. services

((Gas+Water Pipes Electricity+Communication Cables) e.g. snap waterpipes, result in water shortages)

77
Q

How does ground shaking cause injuries and fatalities?

A

people trapped under collapsed infrastructure -> fatalities, injuries

78
Q

how does soil liquefaction destroy natural systems?

A
  • trees on liquefied soil sink, tip over, damage wildlife habitats, cause biodiversity loss
79
Q

how does soil liquefaction destroy properties and infrastructure?

A

infrastructure sink into soil -> tip over -> make rescuing difficult

80
Q

how does soil liquefaction disrupt human services?

A
  • same as disrupts human services for ground shaking
  • roads and railways above liquefied soil sinks -> difficult to rescue ppl

((Gas+Water Pipes Electricity+Communication Cables) e.g. snap waterpipes, result in water shortages)

81
Q

how does landslides destroy natural ecosystems

A
  • fast-moving debris bury huge areas of forest, pollute rivers
  • River blockages may cause floods
82
Q

how does landslides destroy properties and infastructure

A

Debris bury villages, farms destroy infastructure

83
Q

how does landslides disrupt human services

A
  • Debris -> (same as groundshaking disrupt human services)
  • roads, railways blocked by debris -> rescuing/aid more difficult

((Gas+Water Pipes Electricity+Communication Cables) e.g. snap waterpipes, result in water shortages)

Tip: think about what the debris/ground shaking/tsunami can snap (gas, water, electricity

84
Q

how does landslides cause fatalities and injuries

A
  • debris bury/hit people
  • debris block rivers -> floods -> drown ppl

blocking rivers cause flood
flood cause
- drowning
- flood coastal areas e.g., kill wildlife

85
Q

are tsunamis always caused by undersea earthquake

A

no.

  • landslides can also cause it!
86
Q

can tsunamis travel to the coastline?

A

yes!
Tsunamis can travel over thousands of km, devastate huge areas of coastline

87
Q

5 parts: How do tsunami occur?

A
  1. Undersea earthquake causes seabed to be displaced
  2. Large vol. of water lifted, form waves of great wavelength, low height (<1m)
  3. Waves travel -> land (high speed, >800km/h)
  4. On approaching coast, greater friction w/ shallower seabed slows waves down
  5. Waves get closer tgt -> increase in height (15m or more, 30-50km/h onshore)
88
Q

For tsunami, think about w___ and d____

how does tsunami destroy ecosystems?

A
  • seawater flood huge coastal areas, wetlands
  • large amt. of debris carried by waves pollute areas, kill wildlife

water and large amt of debris

89
Q

when think about tsunami, w___ and d____

how does tsunami destroy properties and infastructure?

A
  • fast moving water, large amt. of debris carried in by waves -> sweep away infastructure

water and large amt of debris

90
Q

how does tsunami disrupt human systems?

A
  • fast moving waters, large amt. of debris (same as ground shaking affect human systems)

  • water and large amt of debris
  • snap (electricity, comm. cables)
    electricity, gas, comm., water
91
Q

how does tsunami cause injuries and fatalities?

A
  • sweeping waters drown people
  • large amts. of debris carried in by waves hit, injure, kill people
92
Q

Tephra, think about a___, v___ b____

How does tephra destroy ecosystems

A
  • ash carried thousands of km away by prevailing winds, pollute huge areas o/ forests, rivers, habitats
  • ash suffocate, kill wildlife

all about ash

93
Q

Tephra think about v__b__ and a__

How does tephra destroy properties and infastructure?

A
  • volcanic bombs varying in size can hit properties, cause damage
  • ashfall accumulation on roof of building
  • ash + water -> double weight -> collapse buildings
  • ash corrodes buildings, weakens structure
  • ash damage farmlands, suffocate crops and livestock

yes, ash is corrosive, apparently

94
Q

how big are volcanic bombs?

A
  • from few cm to as big as a car
95
Q

tephra, think about a___ and v__b___

how does tephra disrupt human services?

A
  • ash particles damage plane engines, disrupt air transportation
96
Q

when think about tephra: a__, v__b__

how does tephra cause injuries and fatalities?

A
  • volcanic bombs hit people, cause injuries, loss of lives
  • ashfall cause respiratory, eye problems + suffocation
97
Q

when think about volcanic gases, 2 gases: s__ d___ and c___ d___

how does volcanic gases destroy ecosystems?

A
  • sulfur dioxide causes acid rain when react w/ water in air, damage vegetation, kill wildlife
  • cold carbon dioxide heavier than air, high conc. in low-lying areas like river valleys -> kill wildlife

high conc. in low lying areas as it sinks

btw Co2 still in gaseous form tho it is cold.

98
Q

when think about volcanic gases, 2 gases: s__ d___ and c___ d___

how does volcanic gases cause fatalities?

A
  • sulfur dioxide irritate skin nose eye throat
  • > 3% conc. of carbon dioxide causes breathing difficulties, >15% conc. cause death
99
Q

what gases does volcanic eruptions releaes

A
  • sulfur dioxide
  • carbon dioxide
100
Q

chaare deaths caused by lava flow common?

A

no
- people easily move out of way

101
Q

characteristics of lava flows

A
  • extremely hot
  • can be high silica/low silica
  • travel over some distance from volcano
102
Q

Lava is h___

how does lava flow destroy ecosystem

A
  • hot, low-silica lava travel over some distance, destroy forest, habitats
103
Q

Lava is h___

How does lava flow destroy properties and infastructure?

A

Burn through properties, infastructure

104
Q

How does lava flow affect human services?

A
  • (same as ground shaking destruction)

destroy: (water, gas pipes)
(electricity, comm. cables)

105
Q

how do pyroclastic flow occur

A
  • column of hot ash, gas gets thrown up into air by volcano
  • falls back down to ground due to gravity
106
Q

characteristics of pyroclastic flow

A
  • > 200km/h speeds
  • 700deg celcius temp
  • most devastating of all volcanic hazards
  • travel several kilometers
107
Q

Pyroclastic VS volcanic gases

A

Pyroclastic
- damn fast (>200km/h)
- most hot (700deg)
- gas, ash, rocks
volcanic gases
- sulfur, carbon dioxide
- acid rain (sulf. dioxide), suffocation (carb. dioxide)
- gases only

108
Q

think about t___, h___ f___, a__

how does pyroclastic flow destroy ecosystems?

A
  • huge areas of forest destroyed
  • thick layers of ash cover path of pyroclastic flows -> pollution of forests

ash, hot flows, temperatures

109
Q

how does pyroclastic flow destroy properties and infastructure

A

hot flows burn through homes, infastructure

110
Q

how does pyroclastic flow disrupt human systems

A
  • hot flows (same as how human systems are affected by ground shaking)

hot flows destroy elecrticity, comm. cables, gas pipes, water pipes

111
Q

how does pyroclastic flow cause injuries and fatalities

A

extreme temp. burn, kill people in fraction of a sec.

112
Q

how are lahars formed

A

huge amts. of ash+rocks ejected during eruption mixed w/ water

113
Q

2 example scenarios where lahars are formed (not specific example)

A
  • pyroclastic flows melt snow, ice, mix/w water on volcanic cone
  • Intense rainfall wash down on ash
114
Q

how does lahars destroy ecosystems

A
  • cover forest, ecosystems with thick mud
  • pollute rivers, kill aquatic life
115
Q

how dhow does lahars destroy properties and infastrcuture?

A
  • bury houses, buildings
  • cover properties w/ thick mud which hardens like concrete
116
Q

how does lahars disrupt human services

A
  • roads railways blocked by debris
  • lahars can (same as ground shaking affect human services)

lahars can damage comm. + electricity cables, water, gas pipes => disruption of comm + water shortage + disrupt supply of gas

117
Q

how doe lahars cause fatatlities?

A
  • bury houses w/ residents, killing them
118
Q

are volcanic landslides more common on strato or shield volcanoes? why?

A

strato
- strato taller, steeper volcanic cone, comprises of alternate layers of soldified lava layers + loose tephra

geo (2 decks)

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