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Geography > Hazards (Physical) > Flashcards

Hazards (Physical) Flashcards

1
Q

Describe the crust:

A

The thin layer of the outer shell that we live on, 5-10km thick beneath oceans and 70km thick beneath continents, lithosphere

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2
Q

Describe oceanic plates:

A

An occasionally broken layer of basaltic rocks known as sima - silicon and magnesium

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3
Q

Describe continental plates:

A

Bodies of mainly granite rocks, known as sial - silicon and aluminium

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4
Q

What is the lithosphere?

A

The crust and upper mantle, where tectonic plates are formed

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5
Q

How thick is the mantle?

A

2900km

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6
Q

What is the asthenosphere?

A

A layer of soft, plastic like rock that carries the lithosphere

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7
Q

How hot is the core?

A

5000 degrees C

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8
Q

What are intrusive rocks?

A

Rocks formed by the cooling of molten Magma, that crystallises and solidifies slowly below the surface. Forms coarse grained igneous rocks. Vertical dykes and inclined sills may form within.

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9
Q

What are extrusive rocks?

A

Lava that is in contact with the air or sea. It cools, crystallises and solidifies much quicker than Magma that is still underground. Fine grained rocks with small crystals.

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10
Q

What is gravitational sliding?

A

The movement of tectonic plates under the influence of gravity

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11
Q

What is ridge push?

A

Gravity acting on the weight of the lithosphere near the ridge pushes the older part of the plate in front.

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12
Q

What is slab pull?

A

The lithosphere sinks into the mantle under its own weight following subduction, helping to ‘pull’ the rest of the plate with it.

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13
Q

What events and landforms occur at Constructive boundaries?

A

Volcanoes
Mid ocean ridges

Rift valleys

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14
Q

What events and landforms occur at Destructive boundaries?

A

Powerful earthquakes
Volcanoes

Fold Mountains
Ocean trenches

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15
Q

What events and landforms occur at Collision boundaries?

A

Powerful earthquakes

Fold Mountains

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16
Q

What events and landforms occur at Conservative boundaries?

A

Powerful earthquakes

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17
Q

What is jigsaw fit evidence for tectonic theory (Wegener, 1912)?

A

Similarity in outlines of West Africa and South America as well as other continental areas. Best fit at 1000m below sea level.

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18
Q

What is geological fit evidence for tectonic theory?

A

Ancient rock outcrops from South America and West Africa from over 2000 million years ago were continuous

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19
Q

What is Tectonic fit evidence for tectonic theory?

A

Fragments of the Caledonian mountain belt are found in Scotland, England, Greenland, Canada and Scandinavia

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20
Q

What is glacial deposit evidence for tectonic theory?

A

300 million year old deposits found in Africa, Australia, Antarctica, South America and India suggest ancient ice sheet

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21
Q

What is fossil evidence for tectonic theory?

A

Bands of identical fossils lie across continents, particularly of organisms which could not have travelled.

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22
Q

What happens at a conservative boundary?

A

Two plates do not directly collide but slide past one another

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23
Q

What happens at a constructive boundary?

A

2 plates are moving apart, leaving a gap for magma to rise up through. Volcanoes form but don’t erupt with force and earthquakes occur

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24
Q

Where are rift valleys common?

A

Where 3 plates meet at a junction

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25
Q

What happens at destructive boundaries?

A

Dense oceanic plate descends beneath less dense continental plate. Oceanic plate melted due to friction forming magma

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26
Q

What happens at collision boundaries?

A

Two plates of similar densities move together, causing the material between them to buckle and rise up

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27
Q

Where do rift valleys form?

A

On constructive boundaries

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28
Q

How do rift valleys form?

A

Magma rises and plates move apart
Over a magma chamber, crack and faults appear

Blocks of crust descend into mantle, creating steep sided valleys
Central plateaus sink in the middle, forming lakes

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29
Q

What is a Benioff zone?

A

The further the rock descends, the hotter it gets. Together with the heat from friction begins to melt the plate to magma

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30
Q

What boundaries do ocean trenches form at?

A

Destructive

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31
Q

What are the characteristics of shield volcanoes?

A

Gentle slopes, wide base
Frequent eruptions, basic lava

High speed and low viscosity basaltic lava
Non-violent eruptions

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32
Q

What are the characteristics of composite volcanoes?

A

Steep sides, cone shape
High with narrow base

Explosive eruptions
Layers of alternating ash and lava
Secondary/parasitic cones

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33
Q

What are the two types of lava?

A

Pahoehoe (thin) and A’a (thick)

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34
Q

What is a pyroclastic flow?

A

Fast flowing currents of rock, ash and hot gas from a volcanic eruption
Hot enough to kill in an instant.

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35
Q

What is a lahar?

A

Violent mudflow or debris caused by melting snow or ice.

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36
Q

What are tephras?

A

Rock fragments and particles ejected by volcanic eruption

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37
Q

How is vulcanicity measured?

A
  • Volcanic Explosive Index - more powerful = more explosive
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38
Q

How often do volcanoes erupt

A
  • Around 30-60 erupt each month
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39
Q

What hazards are caused by volcanoes?

A
  • Lava flows
  • Lahars (mudflows)
  • Floods
  • Tephra
  • Acid Rain
  • Toxic Gases
  • Pyroclastic Flows
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40
Q

What are the characteristics of shield volcanoes?

A

Gentle slopes, wide base
Frequent eruptions, basic lava

High speed and low viscosity basaltic lava
Non-violent eruptions

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41
Q

What are the characteristics of composite volcanoes?

A

Steep sides, cone shape
High with narrow base

Explosive eruptions
Layers of alternating ash and lava
Secondary/parasitic cones

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42
Q

Different responses to hazards [6]

A
  • Fatalism
  • Prediction: scientific research can help predict them
  • Adaptation: adjusting lifestyle choices to live with hazards
  • Mitigation: strategies to reduce the impact of a hazard
  • Management
  • Risk sharing: community shares the risk imposed by a hazard & prepares collectively
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43
Q

What are the places plates meet called?

A

Plate margins

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44
Q

What is nuees ardentes?

A

Pyroclastic flows:
Fast flowing currents of rock, ash and hot gas from a volcanic eruption
Hot enough to kill in an instant.

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45
Q

Hazard Management Cycle

A
  • Outlines the stages of responding to events, showing how the same stages take place after every hazard
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46
Q

Park Model

A
  • Graphical representation of steps taken in hazard recovery

- Provides a rough indication of the time frame

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47
Q

Eyjafjallajokull Spatial and temporal evidence (2)

A
  • April 2010, Iceland volcano erupted -> located on spreading ridge
  • Constructive/Divergent plate territory, convection currents
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48
Q

Eyjafjallajokull Effects in Iceland (3)

A
  • Areas flooded due to glacial melt water
  • 700-800 evacuated
  • Ash quantities poisoned animals, people had to wear masks
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49
Q

Eyjafjallajokull Effects elsewhere (4)

A
  • 100,000 flights disrupted for 10million people between 14-21st April 2010.
  • Airlines lost $1.7 billion revenue.
  • 50,000 Kenyan farmers laid off as no food transport
  • People left stranded, unable to commute
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50
Q

Eyjafjallajokull Tectonic setting (3)

A
  • Small volcano in SE rift zone chain of volcanoes
  • Located West of Katla volcano
  • Scientists scared it would trigger Katla.
51
Q

What hazards can earthquakes form?

A

Tsunamis - caused by displacement of large volumes of water
Landslides/Avalanches - shaking of ground can dislodge rock, soil or snow
Soil Liquefaction - vibrations of an earthquake can make soil saturated with water act like a liquid

52
Q

What is soil liquefaction? [2]

A
  • When soil is saturated with water, the vibrations of an earthquake can cause it to act like a liquid
  • Makes soil weaker & easier to deform, so it’s more likely to subside, especially where it has a heavy weight on top (e.g. a building)
53
Q

How often to do low magnitude / high magnitude earthquakes occur?

A

Low magnitude: Every day

High magnitude: much less often

54
Q

Are earthquakes predictable?

A
  • Currently impossible to tell when an earthquake will strike & magnitude
55
Q

What are shockwaves? {2}

A
  • When plates jerk past each other it sends out shockwaves.

- These vibrations are the earthquake - spreads out from the focus.

56
Q

Name 2 social impacts of seismic hazards

A
  • Earthquakes can cause buildings to collapse, killing & injuring people
  • Lack of clean water can cause disease to spread
57
Q

Name 2 environmental impacts of seismic hazards

A
  • Fires started by damaged gas and electricity lines can destroy ecosystems
  • Tsunamis can flood freshwater ecosystems, killing plants & animals
58
Q

Name 2 economic impacts of seismic hazards

A
  • Damage to buildings and infrastructure can be very expensive to repair
  • Damage to industry may mean the country has to rely on expensive imports of goods & energy
59
Q

Name 2 political impacts of seismic hazards

A
  • Shortages of food, water & energy can cause conflict and political unrest
  • Governments may have to borrow money for aid, leading to debt
60
Q

Prevention of seismic hazards [2]

A
  • Not possible to prevent most seismic hazards

- Possible to prevent them posing a risk to people e.g. building giant sea walls to prevent tsunamis

61
Q

Preparedness against seismic hazards [3]

A
  • Earthquake warning systems e.g. TV & SMS
  • Plans for how to respond during an earthquake e.g. evacuation drills
  • Search & rescue teams or fire response units can be set up
62
Q

Adaptation to minimise risks of seismic hazards [2]

A
  • Buildings designed to withstand earthquakes e.g. foundations that absorb an earthquake’s energy
  • Designed to reduce vulnerability to tsunamis e.g. strong tall buildings
63
Q

Short-term responses to seismic hazards [2]

A
  • Rescuing people from collapsed buildings after an earthquake
  • Evacuating people from areas at risk from a tsunami
64
Q

Spatial and temporal setting of Tōhoku Earthquake (3)

A
  • Struck below the North Pacific Ocean, 130km east of Sendai
  • Magnitude 9.0 earthquake 11th March 2011
  • Located on the ‘ring of fire’ - frequent earthquakes
65
Q

Perception of Tōhoku Earthquake (3)

A
  • It was unexpected, few scientists predicted it
  • “Polite demeanour”, little looting afterwards
  • Feb 2017- still 150,000 evacuees who lost homes
66
Q

Causes of Tōhoku Earthquake (3)

A
  • Along a subduction zone, plates collided and energy released as eq’s
  • Pacific plate subducted by Eurasian plate
  • Shaking lasted 6 minutes
67
Q

Impacts of Tōhoku Earthquake (5)

A
  • Killed 15,980 people
  • Caused Fukushima power plant meltdown -> EXPLOSIONS, was nearly fatal
  • 500,000 left homeless
  • $360 billion in damages - the worlds costliest natural disaster
  • 353 cultural properties damaged
68
Q

Responses to the Tōhoku Earthquake (3)

A
  • Tsunami warning sent out 3 min after quake
  • 30km evacuation zone from power plant
  • FDMA dispatched Emergency Fire Response Teams
69
Q

What are tropical storms?

A

Huge spinning storms lasting 7-14 days, with strong winds and torrential rain

70
Q

Where do tropical storms develop?

A

Over warm water - as moist air rises and condenses it releases energy that increases wind speed
Occur in Carribbean sea, Bay of Bengal, China Sea & Northern Australia

71
Q

What are the conditions needed for tropical storms to develop? [3]

A
  • An area of low pressure
  • Warm sea water above 27 degrees
  • A location at least 5 degrees from the equator
72
Q

Why do storms move away from the Equator?

A

The Coriolis effect:

Deflects the path of winds but is weak at the equator

73
Q

What is storm magnitude measured on?

A 
The Saffir-Simpson scale
Category 1 (120km/h winds)
Category 5 (>250km/h winds)
74
Q

How frequent are tropical storms?

A

Around one hundred occur every year
Northern hemisphere: more frequent June-November
Southern hemisphere: more frequent November-April

75
Q

Are tropical storms regular?

A

There are lots of factors affecting where a tropical storm will form so the hazards created by storms are largely irregular.

76
Q

How can tropical storms be predicted? [2]

A
  • Cloud formations can be identified from satellite imagery & used to tell when a tropical storm is forming.
  • Can be tracked using satellite imagery - path of a tropical storm can be predicted accurately
77
Q

2 Social impacts of tropical storms

A
  • Houses are destroyed, so people are left homeless

- People may drown, be injured or killed by debris/ flood water

78
Q

2 Political impacts of tropical storms

A
  • Expensive repairs to buildings, infrastructure etc limit amount of money that can be spent on development
  • People may blame authorities for food, water & energy shortages -> conflict & political unrest
79
Q

2 Economic impacts of tropical storms

A
  • Buildings & infrastructure cost a huge amount to rebuild

- Agricultural land is damaged, affecting commercial farming

80
Q

2 Environmental impacts of tropical storms

A
  • Beaches are eroded and coastal habitats are damaged

- Environments are polluted e.g. by salt water

81
Q

Short term responses to tropical storms [2]

A
  • Occur immediately before, during or immediately after the hazard
  • Evacuating people from areas of risk
82
Q

Prevention of tropical storms

A
  • Can’t be prevented but future developments can be planned to avoid high risk areas
83
Q

Preparedness for tropical storms [3]

A
  • Emergency services can train & prepare for disasters
  • Governments can plan evacuation routes
  • Educating people on how to prepare for a storm
84
Q

Adaptation against tropical storms [2]

A
  • Buildings can be designed to withstand tropical storms e.g. reinforced concrete
  • Flood defences e.g. levees can be built along rivers & coasts e.g. sea walls.
85
Q

[HURRICANE KATRINA 2005] When did Katrina occur?

A

23-31st August 2005

Began in Bahamas

86
Q

[HURRICANE KATRINA 2005] Which area did Katrina damage most?

A

New Orleans, on gulf coast of USA

87
Q

[HURRICANE KATRINA 2005] Why was New Orleans vulnerable? [4]

A
  • Levee system failed
  • Location
  • People didn’t leave- fatalism
  • Severity of storm
88
Q

[HURRICANE KATRINA 2005] Winds

A

Reached 175mph

89
Q

[HURRICANE KATRINA 2005] Why did levee system fail?

A
  • Not been constructed to modern standards.
  • The severity of storm also to blame
  • After 24 hours 80% of area was underwater
90
Q

[HURRICANE KATRINA 2005] How was New Orleans represented in media? [2]

A

As a disaster waiting to happen

Bureaucracy slows down relief effort

91
Q

[HURRICANE KATRINA 2005] Why did the aftermath of storm cause more devastation? [2]

A

Lack of leadership.

Evacuation was only initiated 19 hrs before landfall.

92
Q

[HURRICANE KATRINA 2005] How many DIDNT evacuate?

A

130,000

93
Q

[HURRICANE KATRINA 2005] Social primary [3]

A

60,000 people were stranded in New Orleans.
The Coast guard rescued 33,500 people
Most people fled in private cars and school buses

94
Q

[HURRICANE KATRINA 2005] Primary economic [2]

A

Transported destroyed

Flyovers collapses from flooding and pressure

95
Q

[HURRICANE KATRINA 2005] Environmental primary [2]

A

Water polluted with sewage and oils

Crops / habitats destroyed

96
Q

[HURRICANE KATRINA 2005] Secondary social [3]

A

Looting
1 million refugees traumatised
Racial tensions, many people were African Americans

97
Q

[HURRICANE KATRINA 2005] Secondary economic [3]

A

Destroyed 30 oil platforms
Tourism reduced
Financial cost $200 billion

98
Q

[HURRICANE KATRINA 2005] Secondary environmental [3]

A
  • 16 national wildlife refugees closed.
  • Breeding grounds for marine mammals lost.
  • Flooding - 110,000 out of 180,000 houses
99
Q

[HURRICANE KATRINA 2005] Immediate responses [3]

A
  • Management aid came from USA internal federal aid.
  • Volunteers gave assistance.
  • Approx 58,000 national guard personnel were activated to deal with storms aftermaths troops from 50 states
100
Q

[CYCLONE NARGIS 2008] Why was the Government ineffective? [4]

A
  • Refused aid, politicizing the aid, leaving Burma with a lack of aid
  • Military junta gov.
  • 100,000 ppl killed
  • Low rations
101
Q

[CYCLONE NARGIS 2008] When was Cyclone Nargis?

A

25th April 2008- 4th May

102
Q

Name & explain the three types of wildfires [3]

A

Ground fire: The ground itself (e.g. peat & tree roots) burns, slow smouldering fire
Surface fire: Leaf litter & low-lying vegetation burn. Fire can be low or high intensity
Crown fire: where fire moves rapidly through canopy (top layer of vegetation)

103
Q

How can vegetation type affect wildfire intensity? [2]

A
  • Closely spaced trees in contrast to patchwork forests allow fire to travel easily
  • Eucalyptus trees contain a lot of oil & so burn very easily
104
Q

How do different types of fuels affect wildfires? [2]

A
  • Fine, dry material catch fire & burn most easily

- Large amounts of fuel forming a continuous cover will help the fire spread

105
Q

How does the climate affect wildfire intensity? [3]

A

El Nino: Increases intensity of wildfires in North America

  • Warm, dry weather causes vegetation to dry up, so it’s more flammable
  • Strong winds help the fire burn & spread easily
106
Q

What are different behaviours of fires? [3]

A
  • Creeping fire: moves across ground surfaces fairly slowly
  • Running fire: spreads rapidly & more intense
  • Burning debris: helps fire spread & become more intense
107
Q

Natural causes of wildfires [3]

A
  • Lightning
  • Spontaneous heating
  • Volcanic eruptions
108
Q

Human causes of wildfires [3]

A
  • Dropping cigarettes, campfires, matches
  • Arson
  • Fireworks
109
Q

What % of wildfires are human caused

A

85%

110
Q

What is the ladder effect?

A
  • A wildfire climbing into the canopy
111
Q

Name 2 social impacts of wildfires

A
  • People may be killed or injured if they don’t evacuate in term
  • Wildfires can cause health problems e.g. inhaling smoke can cause long-term breathing difficulties
112
Q

Name 2 Political impacts of wildfires

A
  • Governments can face criticism when wildfires have severe impacts
  • Gov’s may have to change forest management practices to reduce wildfire risk e.g. clearing vegetation to limit fuel
113
Q

Name 2 Economic impacts of wildfires

A
  • Wildfires can destroy businesses -> loss of jobs & income

- Fighting wildifres is costly

114
Q

Name 2 Environmental impacts of wildfires

A
  • Soils are damaged as the fire removes organic matter

- Habitats are destroyed

115
Q

Short-term responses to wildfires [4]

A
  • Diverting away from settlements
  • Evacuating people from at-risk areas
  • Trying to put the fire out
  • Spraying water on roofs of houses to prevent them setting alight
116
Q

Prevention against wildfires [2]

A
  • Public education about the risks of using campfires and BBQs in vulnerable areas
  • Authorities may provide fire beaters to put small fires out before they spread
117
Q

Preparedness for wildfires [2]

A
  • Households having an emergency plan & supplies of food, water & medicine
  • Authorities making emergency shelters available
118
Q

Adaptation for wildfires [2]

A
  • Using non-flammable building materials

- Creating fire breaks (gaps in trees) around settlements to stop fire spreading

119
Q

[ALBERTA 2016] Spatial + Temporal setting [6]

A
  • Spread 540,000 hectares before control on 5th July
  • 10% of city = destroyed
  • Local state of emergency: May 1st 9:57pm
  • First spotted 15km from Fort McMurray
  • May 4th- large enough to make a firestorm
  • August 2nd 2017- extinguished
120
Q

[ALBERTA 2016] Perceptions of the wildfire [2]

A
  • May 2nd + 3rd, people went to school

- 21.6% before the fire thought it had x threat to family

121
Q

[ALBERTA 2016] Causes of wildfire [4]

A
  • No evidence of natural cause - lightning strikes
  • “Perfect storm” of conditions, e.g. 32.8•C, 72km/hr winds, El Niño 2016
  • $15mill fire protection budget cut month before.
  • Reduction of patchwork forests over time.
122
Q

[ALBERTA 2016] Impacts of the wildfire [4]

A
  • $3.6 billion in damages, 88,000 evacu.
  • 2,400 homes destroyed
  • Production of 1 mill oil barrels/day halted (1/4 of Canada’s oil production)
  • Mass job loss + unemployment
123
Q

[ALBERTA 2016] Response to the wildfire? [4]

A
  • ‘Fort McMurry Strong’ signs
  • Wood Buffalo Report, recommendations given on how to respond, e.g pet rescue
  • Some communities 1yr later being rebuilt
  • Prime Minister turned down aid from Australia, Israel, Mexico + Russia

Geography (13 decks)

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