Tectonics Flashcards

1
Q

What are the 5 features of a shield volcano?

A
  • Non-viscous
  • Domes upwards- wider
  • Erupt frequently BUT softly
  • Basaltic magma
  • Volcano gasses diffuse away easily
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2
Q

4 characteristics of Rhyoltic lava

A
  • Coolest
  • High silica
  • Thick + stiff flow (high viscosity traps gasses)
  • Very violent/ cataclysmic
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3
Q

3 characteristics of Andesitic Lava

A
  • Intermediate
  • Slow (intermediate viscosity traps gas)
  • Moderately explosive
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4
Q

5 characteristics of Basaltic Lava

A
  • Low silica
  • Low has content
  • Low viscosity
  • Gentle/effusive eruption energy
  • Hottest
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5
Q

Are crust fracture is another term for a..?

A

Fault

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6
Q

What does the term ‘jökulhaup’ stand for?

A

Masses of ice suddenly released from a glacier by the heat from lava inside a volcano. Can become a mudflow if the ground is unconsolidated.
Glacial outbursts

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7
Q

What does the term ‘Lahar’ mean?

A

Volcanic mudflows commonly created when ash mixes with snow and ice from a volcano summit. Move down volcano flanks like liquid cement.

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8
Q

3 characteristics of a Strato volcano

A
  • Erupt viscous- ANDESITIC or RHYOLITIC
  • Eruptions are explosive
  • Deadly pyroclastic flow
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9
Q

What are the 4 variations of wave?

A

1 Primary First: can travel through
2 Secondary whole world.

3 Love Second: Only move through
4 Rayleigh crust

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10
Q

Why does an intra-plate earthquake occur?

A

1 Stresses build up along ancient faults causing them to become active again

2 Crust that was once weighed down by glaciers is slowly rebounding from the mantle triggering earthquakes

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11
Q

What is the disaster risk equation?

A

Hazard (times) Vulnerability (divided by) capacity to cope

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12
Q

What is a hazard?

A

A physical event which has a negative impact on people causing death, injury, loss of property or destruction of life

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13
Q

What is a disaster?

A

An event that disrupts normal conditions to a point where the place cannot adjust and there is significant loss of life/injuries or economic cost

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14
Q

How to primary waves flow?

A

A compression/expanding movement

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15
Q

How to secondary waves move?

A

A vertical movement

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16
Q

How to love waves flow?

A

A side to side motion

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17
Q

How to rayleigh waves flow?

A

A circular/orbital movement

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18
Q

What two plate boundaries do volcanos occur on?

A
  • Divergent

* Convergent

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19
Q

What is magnitude?

A

The amount of energy released at the epicentre

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20
Q

What does intensity mean?

A

The earthquakes effect on people, structures and the natural environment

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21
Q

How do you measure intensity?

A

Via the mercalli intensity scale

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22
Q

How do you measure volcanic magnitude?

A

Via the volcanic explosively index

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23
Q

Where are shield and strato volcanos found?

A
  • Constructive boundary

* Divergent boundary

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24
Q

What does the term ‘viscosity’ mean?

A

An internal property of a fluid that offers resistance to flow
ie. low viscosity= runny

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25
Q

What are hot spot volcanos?

A

Volcanos that exist as isolated points + aren’t a consequence of a movement of a plate boundary

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26
Q

What is a hot spot track?

A

A chain of extinct volcanos

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27
Q

3 characteristics of primary waves

A
  • Can move through solids + liquids
  • Fastest
  • Push through crust
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28
Q

3 characteristics of secondary waves

A
  • More damaging
  • Can only move through solids
  • Arrive after primary waves
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29
Q

What are the 4 theories to explain reasons for mantle convection?

A

1) mantle convection
2) sea floor spreading
3) subduction
4) slab pull

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30
Q

What are the 2 primary effects of an earthquake?

A
  • Ground shaking

* Crustal fracturing

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31
Q

What are the 3 secondary effects of an earthquake?

A
  • Tsunami
  • Fire
  • Land slides and avalanches
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32
Q

How are volcanos formed?

A

Via the extrusion of lava onto the earths surface

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33
Q

What are the two main volcano types?

A
  • Shield

* Strato/composite

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34
Q

What are the first 2 earthquake waves called?

A
  • Primary

* Secondary

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35
Q

What are the 2 seconds earthquake waves called?

A
  • Love

* Rayleigh

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36
Q

What are surface raptures directly in line with?

A

The focus

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37
Q

What are 3 characteristics of a love wave?

A
  • Produced by body wave
  • Fastest surface wave
  • Most damaging
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38
Q

What are 3 characteristics of a Rayleigh wave?

A
  • Only move through crust
  • Last wave to arrive
  • Move crust up and down
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39
Q

What are strato volcanos built up of?

A

Ash and pyroclastic material

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40
Q

What are shield volcanos built up of?

A

Layers of solidified lava

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41
Q

What is DART?

A

A sea floor bottom pressure recording system capable of detecting tsunamis as small as 1cm

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42
Q

What is a rift valley?

A

When a plate moves apart on continents, crust stretches and breaks into sets of parallel cracks (faults). Land between these fault then collapse, forming steel sides rift valleys.

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43
Q

What the 3 stages of a tsunami?

A

1) Generation
2) Tsunami run-up
3) Landfall

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44
Q

What is slab pull?

A

At a subduction zone the defending part of the oceanic plate pulls the rest of the plate with it

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45
Q

What is subduction?

A

Melting of an oceanic plate as it descends into the mantle at a convergent boundary

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46
Q

What is convection?

A

Movement of mantle material in cells when heated by radiation from the earths core

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47
Q

What is liquefaction?

A

Groundwater and lose soul/sediments are shaken during and earthquake- acts like fluid

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48
Q

What is an intra plate earthquake?

A

An earthquake that occurs at centre of a plate

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49
Q

What is the benioff zone?

A

Zone where descending oceanic plate is in contact with continental plate as it’s subducted.
Zone of earthquake activity created by friction between the two plates

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50
Q

What is the asthenosphere?

A

Partially molten part of the mantle on which the earths tectonic plates lie

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51
Q

What is water column displacement?

A

The movement of a volume of seawater above the point at which the seabed was moved up or down by an earthquake event, such as a thrust.

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52
Q

What is a mantle plume?

A

Hotter areas of mantle that move upwards underneath crust + push up.
Weak spots= hotspots

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53
Q

What is crustal fracturing?

A

Occurs when earths crust causes rock to break and fracture under stress and strain caused by seismic stresses

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54
Q

What is magnitude?

A

Amount of energy released durning a tectonic event

55
Q

What is lithosphere?

A

The rigid, outer most layer of the earth from which tectonic plates are formed. Made up of the crust and upper mantle.

56
Q

What is a hotspot?

A

Intra-plate location where magma from the mantle has broken through weak point on a crust

57
Q

What is the definition of a moment magnitude scale?

A

Most accurate earthquake scale, total energy measurement

58
Q

What is the mercalli scale?

A

An earthquake intensity scale based on 12 levels of damage to areas

59
Q

What is sea floor spreading?

A

Process in which tectonic plates—large slabs of Earth’s lithosphere—split apart from each other.

60
Q

What are seismic waves?

A

Shockwaves created by release of tension at the focus

61
Q

What is palaemagnetism?

A

Magmas and lavas solidify, the iron minerals in the rock align with the earths magnetic field.

62
Q

What is speed of onset?

A

How slow or rapidly the tectonic hazard develops

63
Q

What does the term duration mean?

A

How long the tectonic event lasts

64
Q

What does the term areal extent mean?

A

How widespread the hazard is

65
Q

What does the term spacial predictability mean?

A

How likely scientists are to estimate where a tectonic event will strike

66
Q

What is a hazard profile?

A

A diagram which can be used to show the main characteristics of a hazard.

67
Q

What are the 3 element on the Deggs disaster model?

A
  • Vulnerable population
  • Disaster
  • Tectonic event
68
Q

What is the PAR (pressure and release) model?

A

The PAR model suggests that the socio-economic context of a hazard is important. In poor, badly governed (root causes) places with rapid change and low capacity (dynamic pressures) and low coping capacity (unsafe conditions), disasters are likely.

69
Q

What is a multiple hazard zone?

A

Also known as disaster hotspots, they are an area with vulnerable populations at rick from two or more natural hazards.

70
Q

What can different natural hazards hazards be categorised as?

A

Geophysical (earth related including tectonic movements)

Hydrometeorogical (climate related)

71
Q

What is a mega disaster?

A

The Un states that a mega disaster is when:
• More than 2000 deaths have occurred
•Over 20 000 homeless
•The GDP of a county is reduced by at least 5%
•Dependence on aid from abroad
lee than a year after an event

72
Q

In a globalised world it is even more likely…

A

…that disasters will have a major influence across the planet

73
Q

What is a context hazard?

A

Such as climate change, increases the magnitude and frequency of other hazards (especially hydrometrogical hazards)

74
Q

What are the 4 key titles on the hazard management cycle?

A

1 Mitigation (prevention)
2 Preparedness
3 Response
4 Recovery

75
Q

What is involved in the ‘preparation’ of a hazard?

A
  • Developing preparedness plans
  • Early warning systems
  • Raising public awareness
76
Q

What is involved in the ‘response’ of a hazard?

A
  • Search and rescue efforts
  • Evacuating people where needed
  • Restoring critical infrastructure
77
Q

What is involved in the ‘recovery’ of a hazard?

A

Long term OR short term

  • Rebuilding homes
  • Providing food and temporary shelter
  • Re opening business, schools etc
78
Q

What is involved in the ‘mitigation’ of a hazard?

A
  • Zoning and land use planning
  • Developing and enforcing building codes
  • Protective structures
79
Q

What is the definition of a hazard management cycle?

A

The Hazard Management Cycle takes into account preparedness, response, recovery and mitigation. The Disaster Cycle. The disaster cycle or the disaster life cycle consists of the steps that emergency managers take in planning for, and responding to, disasters.

80
Q

What is the parks response curve (1992)?

A

The Park model is also known as the disaster response curve. Its aim is to show the effects of a hazard on quality of life over a sequence of time.

81
Q

What is the shape of the parks response curve related to?

A

Socio-economic status of the country affected

82
Q

What are the 3 phases of a hazard event according to the parks response curve?

A

Pre disaster

Relief > Rehabilitation > Reconstruction

83
Q

What does the term mitigation mean?

A

Mitigation means to reduce or prevent the effects of something from happening

84
Q

What does the term adaptation mean?

A

Actions taken to adjust to living with tectonic hazards

85
Q

What are 3 options to take when trying to manage a hazard?

A

1) Modify the event- change the tectonic processes/hazards
2) Modify the vulnerability- plan strategies to make the area/population more resilient to the hazard
3) Modify the loss- accept or share the losses of from the hazard

86
Q

What is an example of the option ‘modifying the event’?

A

Lava diversion

Tsunami defences

87
Q

What is an example of the option ‘modifying the vulnerability ’?

A

Preparedness/risk awareness days

Technology monitoring

88
Q

What is an example of the option ‘modifying the loss’?

A

Emergency aid

Insurance

89
Q

Which two plate boundaries create submarine volcanos?

A

Oceanic-Oceanic

Oceanic-Continental

90
Q

In which direction are tectonic plates moving at constructive boundaries?

A

AWAY- divergent

TOWARDS- convergent

91
Q

Why do continental plates never subduct?

A

The asthenosphere is denser

92
Q

Why do conservative boundaries produce no volcanos?

A

There’s no magma- plate isn’t subducted

93
Q

Which plate boundary is the most hazardous?

A

Convergent- destructive

94
Q

What is a transform fault?

A

A large scale break in the crust: conservative boundary

95
Q

What does the Degg Model illustrate?

A

When a hazard becomes a disaster?

96
Q

What does the term threshold mean?

A

The magnitude of a hazard , above which a disaster occurs.

97
Q

What does the term seismic gaps mean?

A

Areas that have not experienced an earthquake for some time and are ‘overdue’

98
Q

What are 2 ways in which an earthquake can be predicted?

A

Areas at high risk identified, together with those likely to suffer sever ground shaking and liquefaction

Seismic gaps can point to areas especially at high risk

99
Q

What are 4 methods to predict a volcanic eruption?

A

Monitoring equipment on volcanos can measure changes as magma chambers fill and eruption nears

Tilt metres record ‘bulging’ as magma rises

Seismometers record minor earthquakes that indicate magma movement

Gas spectrometers analyse gas emissions that can point to increased likelihood of eruption

100
Q

What are 2 methods to predict a tsunami?

A

Seismometers can tell that an earthquake has occurred and locate it

Ocean monitoring equipment can detect tsunamis in the open ocean

101
Q

What are 4 examples of good governance that reduce disaster vulnerability?

A

Meeting basic needs- providing sufficient food and water

Planning- land use planning/zoning

Environmental management- preventing exacerbating factors such as deforestation, effective monitoring systems

Preparedness- education and community awareness

102
Q

What 3 other geographical factors influence resilience and vulnerability?

A

Population density
Isolation and poor accessibility
Degree of unbanisation

103
Q

What is a hazard profile?

A

A way of summarising the physical processes that all hazards share to help decision makers determine the places most at risk.

104
Q

What does the moment magnitude scale measure (MMS)?

A

The energy released via an earthquake

105
Q

What does the mercalli scale measure?

A

The damaging effects (ie shaking) produced by earthquake

106
Q

What are effusive eruptions of basaltic lava with love VEI associated with?

A

Constructive boundaries or plumes

107
Q

What are explosive eruptions with high VEI of andesitic it rhyolitic lava associated with?

A

Destructive boundaries

108
Q

What does the term resilience mean?

A

The degree to which a society or environment can absorb a hazardous event and yet remain within the same state of an organisation- it’s ability to cope with stress and recover.

109
Q

What are the 4 sources of evidence for continental movement?

A

Carboniferous glaciation round is southern hemisphere continents

Fossil remains of small fresh water reptile have been found in both S america and africa

Coal found in antarctica: it is unlikely to have formed at its current latitude, and requires tropical climate

Basaltic lava flows are located where continents tear apart

110
Q

What do volcanos lie on?

A

Mid-oceanic ridges

Volcanic arcs that border trenches

111
Q

What does the term subaerial mean?

A

above sea level (volcanos)

112
Q

What does the term hot spot track mean?

A

A chain of extinct volcanos form when the overlying plate moves over a fixed plume

113
Q

What is the definition of a tsunami?

A

A series of larger than average waves which are usually caused by submarine earthquakes or volcanic eruptions. Tend to occur along plate boundaries.

114
Q

What is seismic activity?

A

Seismic activity is defined as the types, frequency and size of earthquakes that happen over a period of time in a certain area.

115
Q

Why do disasters happen?

A

Failures of development which increase vulnerability

116
Q

What does the term root cause mean?

A

Political or economic systems that control who has power and access to resources such as money eg. level of development, national debt, government corruption

117
Q

What does the term dynamic pressure mean?

A

The effect the root causes might have eg. poor infrastructure, no defences, deforestation

118
Q

What does the term unsafe conditions mean?

A

The conditions the dynamic pressures lead to ie. lack of evacuation, illegal housing in unsafe conditions- disease outbreaks etc.

119
Q

What are the 3 plate boundaries?

A

Divergent-
oceanic-oceanic

Convergent-
oceanic-continental, continental- continental

Conservative

120
Q

What does the hypo centre mean?

A

The point within the earth where an earthquake originates

121
Q

What does the term epicentre mean?

A

The point on the earths surface vertically above the focus of an earthquake

122
Q

What does slab pull mean?

A

A subduction zone- the descending part of the oceanic plate pulls the rest of the plate with it

123
Q

What does sea floor spreading mean (or palaeomagnetism)?

A

The movement of oceanic crust from constructive wave boundary, recorded by magnetic stripes in basaltic rock. Magma fills gaps, solidifies forming new crust.

124
Q

What does the term mantle convection mean ?

A

Movement of material in cells when heated by radiation > radioactive elements decay, move through mantle

125
Q

What are the 3 primary volcanic hazards?

A

Lava flows
Gas eruptions
Pyroclastic flows

126
Q

What does the term hazard management mean?

A

A process in which governments and other organisations work together to protect people from the natural hazards that threaten their communities

127
Q

What is the definition of land use zoning?

A

Process by which governments regulate how land in a community may be used (eg industrial, commercial etc). Common in wealthy countries

128
Q

What is involved in diverting lava flows?

A

Building barriers, digging channels to try and diverge the lava into a safer direction.
A fairly ineffective method

129
Q

What is involved in GIS mapping?

A

Can be used in all stages of the disaster management cycle > eg identify where evacuation routes will be

130
Q

What is the main cause of death during an earthquake?

A

Collapsing buildings

131
Q

How are NGOs a crucial role in disaster management?

A

Especially important when local government is struggling to respond, or doesn’t have resources to do so. Can provide funds, rescue efforts etc

132
Q

Why is insurance key in hazard management?

A

It provided individuals and businesses with the money they need to repair and build

133
Q

What are the 3 destructive plate boundaries?

A

oceanic-continental
oceanic-oceanic
continental-continental