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Geography > 1) Global hazards > Flashcards

1) Global hazards Flashcards

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1
Q

What are the four components of the earth?

A

Crust
Mantle
Outer Core
Inner Core

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2
Q

Characteristics of crust 3

A

Divided into tectonic plates
Around 20c
Between 8-65 km

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3
Q

What are the two types of tectonic plates?

A

Oceanic

Continental

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4
Q

Characteristics of oceanic plates

A

Thinner and denser

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5
Q

Characteristics of continental plates?

A

Thicker and less dense

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6
Q

Characteristics of mantle 2

A

Semi-molten rock

1200c

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7
Q

Characteristics of outer core 2

A

3700c

It is liquid

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8
Q

Characteristics of inner core 2

A

5500c

A solid ball of iron and nickel

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9
Q

What is a convection current?

A

When hot materials (molten rock) rise because they are less dense and cooler rock sinks because it is denser

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10
Q

How do convection currents move tectonic plates?

A

Magma near the outer core is heated
As it warms, it expands and becomes less dense
As it nears the crust, it begins to cool
The cooling magma becomes more dense and begins to sink
This motion creates circular convection currents in the mantle
These currents create friction with the crust above and cause it to move

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11
Q

What is a destructive plate boundary?

A

Two plates move towards each other
Where an oceanic plate and a continental plate meet, the denser oceanic plate is forced into the mantle and destroyed
This creates volcanoes and deep ocean trenches

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12
Q

Example of a destructive boundary

A

The pacific plate is being subducted under the Eurasian plate

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13
Q

What is a collision plate boundary?

A

Both plates are made from continental crust
They move towards each other
Both plates are forced upwards
This creates fold mountains

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14
Q

Example of collision plate boundary

A

The Eurasian and Indian plates are colliding to form the Himalayas

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15
Q

What is a constructive plate boundary?

A

Two plates move away from each other

Magma rises to fills the gap and cools to create new crust

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16
Q

Example of constructive plate boundary

A

The Eurasian and North American plates are moving apart at the Mid-Atlantic Ridge

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17
Q

What is a conservative plate boundary?

A

Two plates move sideways past each other or move in the same direction at different speeds
Crust isn’t created or destroyed

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18
Q

Example of conservative plate boundary

A

The Pacific and North American plate are moving past each other at the San Andreas fault

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19
Q

What is continental drift?

A

When convection currents move plates away from each other

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20
Q

What are hot spots?

A

Areas of intense volcanic activity that are away from plate boundaries

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21
Q

How was the chain of Hawaiin Islands made?

A

There is a hotspot in the crust

The hotspot remains stationary but the unusual heat causes the plats above it to move

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22
Q

How is a hotpot formed?

A

When a plume of hot magma form the mantle moves towards the surface, causing a flow of heat from the mantle to the crust

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23
Q

What is the volcanic cloud?

A

Gas steam and ash escaping from the volcano

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24
Q

What do the secondary vent and cone do?

A

Allow magma to escape from the sides of the volcano

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25
Q

Why do earthquakes occur at destructive boundaries?

A

Tension builds as one plate gets stuck as it subducts

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26
Q

Why do earthquakes occur at collision boundaries?

A

Tension builds as the plates are forced together

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27
Q

Why do earthquakes occur at constructive boundaries?

A

Tension builds along cracks within the plates as the plates move away from each other

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28
Q

Why do earthquakes occur at conservative boundaries?

A

Tension builds up when plates moving past eachother get stuck

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29
Q

How do earthquakes form?

A

Tension builds between plates
Convection currents build up, increasing potential energy
When potential energy is greater than friction, the plates eventually jerk past eachother, releasing the tension as shock waves
These seismic waves spread out from the focus

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30
Q

What is the focus of an earthquake?

A

The point in the earth where the quake starts

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31
Q

What is the epicentre?

A

The point on the earth’s surface above the focus

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32
Q

What are shallow focus earthquakes and where do they occur?

A

Caused by tectonic plates moving at or near the surface

They have a focus of between 0 and 70 km below the earth’s surface

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33
Q

What are deep focus earthquakes and where do they occur?

A

Caused by crust that has previously subducted into the mantle and are moving towards the core
Focus of 70 - 700 km below earth’s surface

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34
Q

Why are deep-focus earthquakes less damaging?

A

The shock waves have to travel through more rock to reach the surface so they lose much of their power

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35
Q

Another name for a transform plate boundary

A

Conservative

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36
Q

Another name for a convergent plate boundary

A

Destructive

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37
Q

Another name for a divergent plate boundary

A

Constructive

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38
Q

How do volcanoes form at destructive plate margins?

A

The oceanic plate is subducted
A pool of magma forms
It rises through vents in the crust
The magma erupts onto the surface

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39
Q

How do volcanoes form at constructive plate margins?

A

The magma rises up into the gap, forming a volcano

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40
Q

What are the two types of volcano?

A

Composite and shield

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41
Q

Characteristics of composite volcanoes

A

Tall and narrow
Violent explosions and lava bombs
Thick, sticky lava

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42
Q

Where do composite volcanoes occur?

A

Destructive plate boundaries

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43
Q

Example of composite volcano

A

Mount St Helens

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44
Q

Characteristics of shield volcanoes

A

Small and wide
Gentle eruptions, no lava bombs
Thin, runny lava

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45
Q

Where do shield volcanoes occur?

A

Hotspots or constructive plate boundaries

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46
Q

Example of shield volcano

A

Mauna Loa in Hawaii

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47
Q

What is bi-lateral aid?

A

Government to government

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48
Q

What is multilateral aid?

A

Co-ordinated response of many governments

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49
Q

What are NGOs?

A

Organisations such as Oxfam

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50
Q

3 ways of reducing the impact of tectonic hazards?

A

Building designs
Predicting and monitoring volcanoes
Early warning system for earthquakes

51
Q

How can building designs reduce the impact of a tectonic hazard? 3

A

Buildings can be built from reinforced concrete or by using materials that absorb an earthquake’s energy
Existing buildings can be strengthened (e.g. cross bracing)
Pipelines can be designed to flex and not break

52
Q

How can early warning systems help reduce the impact of a tectonic hazard? 3

A

People can start to prepare
Utilities can be shut off
People doing delicate jobs can stop, e.g. surgeons

53
Q

How can predicting and monitoring volcanoes during eruptions reduce the impact of a tectonic hazard? 3

A

It gives people time to evacuate
Flights can be diverted from ash covered zones
Gas masks can be distributed early on

54
Q

What is mitigation?

A

Reducing the impact of an earthquake

55
Q

What is retrofitting?

A

The addition of new technology to older buildings

56
Q

Examples of ways that buildings can be earthquake-proofed 3

A

Cross bracing
Automatic sprinkler system and gas shut off
Shock absorbers

57
Q

How do tiltmeters work?

A

They measure the shape of volcanoes to detect bulges

58
Q

How can measuring the soil/water pH help us predict earthquakes/eruptions?

A

May become more acidic before an eruption

59
Q

What causes water and soil to become more acidic before an eruption?

A

An increase in sulfur levels

60
Q

How can satellite imaging help us predict earthquakes/eruptions?

A

thermal imaging shows whether magma is rising

61
Q

How can gas emissions help us predict eruptions?

A

Sulfur dioxide and carbon dioxide levels rise as magma rises

62
Q

4 ways in which technology can be used to predict earthquakes

A

Tiltmeters
Measuring soil/water pH
Satellite imaging
Gas emisions

63
Q

Which earthquake did we study?

A

The Nepal 2015 Earthquake - SEE CARDS

64
Q

In which direction do winds move?

A

From areas of high pressure to areas of low pressure

65
Q

What does hot, rising air do?

A

Create a belt of low pressure

66
Q

What does cool, sinking air do?

A

Create a belt of high pressure

67
Q

Why is the equator hot and wet?

A

The hot air causes a belt of low pressure, which creates rainfall

68
Q

How do the three belts work?

A

The sun heats the earth at the equator, creating low pressure belt
The air cools and moves to 30 north and south of equator
Here, the cool air sinks, creating a high pressure belt with low rainfall
The cool air moves as surface winds either towards the poles or equator
At 60 north and south of the equator, the warmer surface winds meet cold air from the poles. The warm air rises, creating low pressure
Some air move towards the equator and the rest to the poles
At the poles, cool air sinks, creating high pressure.
This air is drawn back to the equator as surface winds

69
Q

What are surface winds blowing towards the equator called?

A

Trade winds

70
Q

Which direction do trade winds blow in the northern hemisphere?

A

From NE

71
Q

Which direction do trade winds blow in the southern hemisphere?

A

From SE

72
Q

Why do trade winds form clouds?

A

The two meet at the equator and are heated by the sun, making them rise and form clouds

73
Q

What are surface winds blowing to the poles called?

A

Westerlies

74
Q

Which direction do westerlies blow from in the southern hemisphere?

A

NW

75
Q

Which direction do westerlies blow from in the northern hemisphere?

A

SW

76
Q

What are the four types of climate?

A

Polar, dry, temperate, tropical

77
Q

Characteristics of polar climate

A

Cold all year round

78
Q

Characteristics of temperate climate

A

Moderate summers and winters

79
Q

Characteristics of tropical climate

A

Hot and wet

Found near the equator - rising air from two cells meeting causes low pressure and lots of rainfall

80
Q

Characteristics of dry climate

A

Low rainfall

Sinking air from two cells causes high pressure and low rainfall

81
Q

What are winds like in pressure belts?

A

Weak

82
Q

What are winds like between pressure belts?

A

Strong

83
Q

How is extreme wind formed?

A

Wind moves from areas of high to low pressure
Winds are weak in high and low belts
Winds are strong between belts
When the difference between high and low pressure belts is large, winds can be very strong

84
Q

How is extreme rain formed?

A

Precipitation is formed when warm air rises and cools, causing water vapour to condense
Air rises in low pressure belts. Rain is frequent and intense here
In high pressure belts, rainfall is low
The exact location of the pressure belts changes over time, so places like the UK can experience extreme rainfall

85
Q

How is extreme temperature formed?

A

The equator receives most of the suns energy
The poles receive the least
Heat drives atmospheric circulation as warm air moves from the equator to the poles
Near the equator, the high pressure means there are few clouds to block the suns energy so it is often very hot

86
Q

Hottest place on earth
Description of conditions
Explanation for conditions

A

Congo jungle
Over 30c the whole year
Sun rays strongest at equator/little cloud cover

87
Q

Coldest place on earth
Description of conditions
Explanation for conditions

A

Antarctica
-50c in some areas
Albedo affect reflects heat/sun rays hit at angle

88
Q

Windiest place on earth
Description of conditions
Explanation for conditions

A

Commonwealth Bay, Antarctica
Average speed of 80km/hr
Katabatic winds carry wind down from high ground

89
Q

Place on earth that experiences most tornadoes
Description of conditions
Explanation for conditions

A

Tornado Alley
Over 500 tornadoes/year
Warm moist air from Mexico and dry cool air from Canada meet
Change in wind direction and increased speed creates spinning effect

90
Q

Wettest place on earth
Description of conditions
Explanation for conditions

A

Cherrapunji, India
9300mm of rain in July 1861
Clouds forced to rise rapidly when meet Khasi Hills = relief rainfall

91
Q

Driest place on earth
Description of conditions
Explanation for conditions

A

Atacama, Chile
15mm of rain on average
Rain shadow of Andes + cold ocean current = no moist air to form clouds

92
Q

What are tropical storms?

A

Rapidly revolving storms characterised by low pressure

93
Q

Names for tropical storms 3

A

Hurricanes, typhoons, cyclones

94
Q

What is the Coriolis force and how does it work?

A

It causes the rotation of hurricanes
In the northern hemisphere, it deflects movement to the right
In the southern hemisphere, it deflects movement to the left
This means it sucks air in and creates an eye

95
Q

What causes extreme winds in tropical storms?

A

An area of low pressure at the centre of the storm creates a big pressure difference to the surrounding area

96
Q

What causes extreme rainfall in tropical storms?

A

Large amounts of warm, moist air are sucked in

The air rises and condenses, causing rain

97
Q

Where do the majority of tropical storms take place?

A

Between 5 and 30 degrees north and south of equator

Mostly in northern hemisphere

98
Q

How is a hurricane formed?

A

Sea temperatures reach 27c
The heat from the warm ocean is passed into the air by conduction.
This causes the warm air to rise, creating an area of low pressure
Wind moves from high to low pressure so is sucked in
The cloud gets hotter. The more moisture, the more heat
When winds reach 75 mph, it is a hurricane
As pressure drops and storm grow, it is affected by Coriolis force so it revolves and sucks in air from around it
An eye develops
When it reaches land, there is nothing to give it any energy so it slows down

99
Q

At what wind speed will it be classed as a hurricane?

A

75 mph

100
Q

Which typhoon do we study?

A

Typhoon Haiyan - SEE CARDS

101
Q

What is it called when water and air currents weaken or reverse?

A

El Nino

102
Q

What is it called when water and air currents get stronger?

A

La Nina

103
Q

How often does La Nina occur?

A

Every 2-7 years

104
Q

What are air currents normally like?

A

There is low pressure over the western Pacific where air rises. This is blown east
There is high pressure over the East around south america where air sinks, causing clear skies and dry weather
Trade winds blow to West , moving air back to the western side (Australia)

105
Q

What does La Nina do?

A

It makes conditions more extreme

Trade winds are stronger and more cold water rises in the east

106
Q

Characteristics of La Nina weather

A

Heavy rainfall and floods in the west - Australia

Droughts and less rainfall in the east - S. America

107
Q

What does El Nino do?

A

Conditions are reversed
High pressure in west and low pressure in the east
Trade winds blow east
Winds high in atmosphere blow west

108
Q

Characteristics of El Nino weather

A

Lower rainfall/ droughts in the west - Australia

Flooding to the east - S. America

109
Q

What is a drought?

A

A period of time where rainfall is below average

110
Q

Causes of drought 2

A

Changes in atmospheric circulation (Nina and Nino)

High pressure systems block the weather systems that cause rain

111
Q

Distribution of Droughts

A

The areas most at risk include South Africa, Australia

112
Q

Where to compare for extreme weather?

A

UK and Australia

113
Q

Average summer temperature in Australia

A

33c

114
Q

Average temperature in UK in summer

A

23c

115
Q

Highest extreme temperature in Australia

A

51c

116
Q

Highest extreme temperature in UK

A

38.5c

117
Q

Lowest extreme temperature in Australia

A

-23c

118
Q

Lowest extreme temperature in Uk

A

-27.2c

119
Q

Worlds driest inhabited continent

A

Australia

120
Q

Average rainfall in Australia

A

465 mm

121
Q

Average rainfall in UK

A

1150 mm

122
Q

Where has stronger extreme winds

A

Australia

123
Q

Strongest wind recorded in Australia

A

400 km/h

124
Q

Strongest wind recorded in UK

A

220 km/h

Geography (30 decks)

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