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Geography > Unit 1: Section A: The challenge of natural hazards > Flashcards

Unit 1: Section A: The challenge of natural hazards Flashcards

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1
Q

Define natural hazard

A

A natural process which could cause death, injury or disruption to humans or destroy property and possessions

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2
Q

Define natural disaster

A

A natural hazard that has already happened

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3
Q

Define natural event

A

A natural process which doesn’t pose any threat to human activity

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4
Q

What are the 2 main types of hazard?

A

1) Geological hazard
2) Meteorological hazard

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5
Q

What is a geological hazard?

A

-A hazard caused by land and tectonic processes
-Examples are earthquakes and volcanoes

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6
Q

What is a meteorological hazard?

A

-A hazard caused by weather and climate
-An example is a tropical storm

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7
Q

Define hazard risk

A

The probability of people being affected by a hazard

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8
Q

What are the main factors that affect hazard risk?

A

-Population density
-Poverty/Capacity to cope
-Type of natural hazard
-Frequency of hazard
-Magnitude of hazard

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9
Q

How does population density affect hazard risk?

A

More people in an area when a natural event occurs, the higher the hazard risk

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10
Q

How does poverty/capacity to cope with a hazard affect the hazard risk?

A

-In poorer parts of the world people may be forced to live in areas with a high chance of hazards happening
-In LICs people may not be able to afford defences

-In addition the better a population can cope with an event the lower the risk of them being affected

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11
Q

How does the nature of the hazard affect the hazard risk?

A

-The risk of some hazards is greater than others
-Natural hazards that occur more often have a higher risk
-More severe hazards TEND to have a greater impact and risk

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12
Q

Define the term primary effects

A

The immediate impacts caused by a natural hazard

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13
Q

What are the main primary effects of a natural hazard?

A

-Buildings and roads are DESTROYED by natural hazards (Earthquakes/volcanoes/tropical storms)

-People may be injured or killed (e.g when a building collapses)

-Crops and water supplies may be damaged or contaminated

-Electricity cables, gas pipes, water pipes. sewage pipes and network communications may be damaged CUTTING OFF supplies

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14
Q

Define the term secondary effects

A

The effects that occur later on often the result of the primary effects

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15
Q

What are the main secondary effects after a natural hazard?

A

-The initial hazard may trigger other hazards (earthquakes may trigger tsunamis)

-Aids and emergency vehicles CAN’T get through because of blocked roads and bridges - May lead to MORE deaths

-Shortage of clean water and lack of sanitation makes it easier for DISEASE to spread

-FOOD SHORTAGES Can occur if crops are damaged and livestock are killed

-The country’s economy can be weakened - damage to businesses can cause unemployment and the reconstruction can be expensive

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16
Q

What are the immediate responses to a natural hazard?

A

-Evacuate people (before the hazard occurs if possible)

-Treat the injured people and rescue anyone

-Recover dead bodies to prevent disease from spreading

-Provide temporary supplies of electricity and gas if necessary

-Provide FOOD, DRINK and SHELTER

-Foreign governments or charities may send aid workers, supplies or financial donations

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17
Q

What are the long term responses to a natural hazard?

A

-Repair homes or rehouse people

-Repair or rebuild buildings, roads, railways and bridges

-Reconnect broken electricity, water, gas and communication connections

-Improve forecasting, monitoring and evacuation plans

-Boost economic recovery (E.g tourism)

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18
Q

What are the layers of the earth?

A

-Crust
-Mantle
-Outer core
-Inner core

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19
Q

What are the properties of the core?

A

-Core is extremely hot and has temperatures of up to 5500 degrees Celsius

-The inner core is more solid due to the pressure

-The outer core is more of a liquid

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20
Q

What are the properties of the mantle?

A

-Made up of 2 layers

-The uppermost layer is called the LITHOSPHERE and is the coolest and solid

-As you move closer to the core the mantle becomes more fluid (like custard) and the temperature increases

-This is called the aesthenosphere and is the main source of magma

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21
Q

What are the 2 types of crust?

A

-Oceanic crust
-Continental crust

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22
Q

What is the earths crust divided into?

A

Tectonic plates

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23
Q

What are the properties of the oceanic crust?

A

-Young rock (<200 million years old)
-Thin (6-20km thick)
-Composed of basalt
-Can be renewed/destroyed

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24
Q

What are the properties of continental crust?

A

-Old rock (>1500 million years)
-Thick (20-70km thick)
-Composed of granite
-Cannot be renewed/destroyed

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25
Q

What causes the tectonic plates to move?

A

-Convection currents
-Slab pull
-Ridge push

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26
Q

What is the continental drift theory?

A

-The theory of plate tectonics is linked with the fact that the earth’s crust moves

-The theory states that 200 million years ago there was a supercontinent called Pangea

-Thus theory helps explain the formation of the world today

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27
Q

What is the place where plates meet called?

A

Plate margins or plate boundaries

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28
Q

What is ridge push?

A

-As plates move apart magma rises
-The magma then cools forming new plate material
-As this cools it becomes denser and slides down away from the ridge
-The force of this causes plates to move away from each other

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29
Q

What is slab pull?

A

-At a subduction boundary a denser heavier plate subducts the less dense plate
-As the plate gets pulled underneath by gravity the force of this pulls the rest of the plate with it

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30
Q

What are the types of plate margin?

A

-Destructive
-Constructive
-Conservative
-Collision

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31
Q

What happens at destructive plate boundaries?

A

-This occurs when one continental plate moves towards an oceanic plate
-The denser oceanic plate then subducts and gets destroyed
-This creates gas-rich magma

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32
Q

What natural hazards occur at destructive plate boundries?

A

-Volcanoes
-Earthquakes

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33
Q

What happens at collision plate boundaries?

A

-When two continental crusts collide
-They squeeze together as they have the same density forming fold mountains

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34
Q

What natural events happen at collision plate boundaries?

A

Earthquakes only

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35
Q

What is an example of a destructive plate margin?

A

The Nazca plate subducts the South American plate

(On diagrams Nazca on the left south american on the right)

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36
Q

What is an example of a collision plate boundary?

A

The Indian plate collides with the Eurasian plate

(Indian on the left Eurasian on the right)

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37
Q

What happens at constructive plate margins?

A

This is where two plate boundaries move apart from each other
-Magma then rises filling the gaps
-This then cools creating new crust

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38
Q

What is an example of constructive plate margins?

A

Eurasian plate and the North American plate - forming the mid Atlantic ridge

(North American on the left Eurasian on the right)

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39
Q

What happens at conservative plate boundaries?

A

-This happens when two plates are either moving sideways past each other
-Or moving in the same direction at different speeds next to each other

-Crust isn’t created or destroyed

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40
Q

What is an example of a conservative plate boundary?

A

Pacific plate and the north american plate - forming the San Andreas fault

(Pacific plate on the left north american on the right)

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41
Q

Which natural events happen at constructive plate boundries?

A

-Earthquakes
-Volcanoes

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42
Q

Which natural events happen at conservative plate boundries?

A

-Earthquakes only

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43
Q

How do volcanoes form at destructive plate margins?

A

-The denser oceanic crust subducts into the mantle and melts
-This forms magma which rises through cracks called vents
-The magma erupts at the surface (Now called lava) forming a volcano

44
Q

What type of volcano forms at destructive plate boundries?

A

Composite volcano

45
Q

What are the properties of composite volcanoes?

A

-They have steep sides which are made up of alternating layers of ash and lava
-Lava is sticky and viscous (acidic)
-Eruptions are violent due to a high gas content
-However eruptions don’t happen often

46
Q

How are volcanoes formed at constructive plate boundaries?

A

-As the plates move apart, magma rises up from the mantle

47
Q

What type of volcano is formed at constructive plate boundries?

A

Shield volcanoes

48
Q

What are the properties of shield volcanoes?

A

-Wide base and gently sloping sides
-Lava is runny and flows a long way
-Lava is basic (Not acidic)
-Frequent eruptions
-However they are not violent

49
Q

Define the focus

A

The point where the earthquake is generated

50
Q

Define the epicentre

A

The point on the earth’s surface right above the focus

51
Q

Define seismic waves

A

The form in which energy is released from the focus

52
Q

Define fault lines

A

Fractures or zones of fractures where significant displacement occurs

53
Q

How are earthquakes formed at destructive plate boundries?

A

-Formed at the subduction zone
-Where tension builds as one plate gets stuck when they move away from each other
-The plate eventually jerks past each other sending out shock waves

54
Q

How are earthquakes formed at constructive plate boundries?

A

Tension builds along cracks (fault lines) as the plates move away from each other
-Sending out shock waves

55
Q

How are earthquakes formed at conservative plate boundries?

A

-Tension builds up when the plates are grinding past each other
-The start to stick and may get stuck
-The plates suddenly jolt apart releasing shock waves

56
Q

Where are the seismic waves strongest?

A

At the focus

As they spread out they get weaker

57
Q

What are the methods of measuring the magnitude of earthquakes?

A

-Richter scale
-Mercalli scale

58
Q

What is the richter scale?

A

-The richter scale uses a seismograph to measure the difference of speed between P-waves and S-waves
-It is a logarithmic scale
-So a magnitude of 7 is TEN times more powerful then a magnitude of 6

-This is more scientifically accurate than the Mercalli scale but requires specialist equipment

59
Q

What is the Mercalli scale?

A

-The Mercalli scale uses a range of 1-8
-He based the scale of the earthquake depending on the damage caused
-1 being not damaging 8 being catastrophic

-It isn’t scientifically accurate yet doesn’t require specialist equipment

60
Q

What are the types of seismic waves?

A

-Surface waves
-P-waves
-S-waves

61
Q

What are the properties of p-waves?

A

-They are the first waves to hit
-They can travel through solids and liquids
-They cause buildings to move up and down and are the least damaging
-So buildings may survive

62
Q

What are the properties of S-waves?

A

-They are the second waves to hit
-They can only move through solids
-They move buildings side to side

63
Q

What are the properties of surface waves?

A

-They are the most damaging
-They go up and down like waves on water
-This causes buildings to twist and collapse
-These are the last to hit

64
Q

What are the hazards from volcanoes?

A

-Tephra
-Pyroclastic flow
-Lava
-Lava bombs
-Gas
-Lahars

65
Q

What is tephra?

A

A mixture of ash and lava bombs which travels long distances

66
Q

What are the impacts of tephra?

A

-Can destroy cars and any mode of transport
-Can disrupt travel
-Causes roofs to cave in under the weight
-Covers farmland and landscapes

67
Q

What is pyroclastic flow?

A

-The most deadly of all the hazards
-A mixture of hot poisonous gas and ash that is blasted into the atmosphere
-It then tumbles down the side of the volcano at a high velocity

68
Q

What are the impacts of pyroclastic flow?

A

-Hot gas kills people
-Will bury whatever is in its path

69
Q

What are lava bombs?

A

A mass of molten rock ejected during an eruption

70
Q

What are the impacts of lava bombs?

A

-Could severely injure people
-Can cause secondary fires and damage buildings

71
Q

What is the gas released from a volcano?

A

-The invisible gas makes up the magma
-They can escape before an eruption
-This can kill people as it is poisnonous

72
Q

What are the impacts of gas (volcanoes)?

A

-Can kill many people or cause them to fall unconscious
-Can poison land/soil

73
Q

What are lahars?

A

-A violent type of mudflow or debris composed of pyroclastic material
-Which usually travels down valleys

74
Q

What are the impacts of lahars?

A

-They can bury and destroy manmade structures like roads
-Can trap people
-Can cause severe riverbank erosion
-Can clear areas of woodland or agriculture

75
Q

What is soil liquefaction?

A

-The shaking of the ground (During the earthquake) forces water to the surface

-This causes the ground to lose its strength

-Therefore buildings then sink

76
Q

What is a positive correlation?

A

As one factor increases the other factor increases

77
Q

What is a negative correlation?

A

As one factor increases another factor decreases

78
Q

What is the GPD per capita in Chile?

A

-GPD per capita is 30 billion

79
Q

What were the primary effects of the earthquake in the HIC (Chile)?

A

-Around 500 people were killed and 12,000 injured (80,000 affected)

-220,000 homes, 4500 schools, 53 seaports, 56 hospitals and other buildings were destroyed

80
Q

What were the secondary effects of the earthquake in the HIC (Chile)?

A

-1500 Km of roads were damaged badly by landslides – remote communities were cut off for many days

-A fire at a chemical plant near Santiago – The area had to be evacuated

81
Q

What is the earthquake management like in the HIC (Chile)?

A

-Chile has one of the most effective disaster relief infrastructures in the world

-This is due to the rigorous building codes, evacuation simulations and preparation

82
Q

What was the immediate responses to the earthquake in a HIC (Chile)?

A

-Temporary repairs made to the important route 5 north-south highway meant that aid could be transported from Santiago to affected areas

-A national appeal raised US$60 million – enough to build 30,000 small emergency shelters

83
Q

What were the long term responses to the earthquake in a HIC (Chile)?

A

-A month after the earthquake Chile’s government launched a housing reconstruction to help nearly 200,00 homes affected

-Chile’s strong economy could be rebuilt without the need of much foreign aid

84
Q

What is the GPD per capita in Nepal?

A

-The GPD per capita is 10 billion

85
Q

What were the primary effects of the earthquake in an LIC (Nepal)?

A

-9000 people died and 20,000 injured – over 8 million people were affected (1/3 of the population)

-3 million people left homeless after homes were destroyed

-1.4 million people needed food, water and shelter in the days and weeks after the earthquake

86
Q

What were the secondary effects from the earthquake in an LIC (Nepal)?

A

-Avalanches on Mount Everest killed at least 19 people

-An avalanche in Langtang region left 250 people missing

-A landslide blocked the Kali Gandaki River (90 miles from Katmandu) - Many people evacuated in case of flooding

87
Q

What was earthquake management like in an LIC (Nepal)?

A

No warning system
-More than 50% of its population lives below the poverty line

-The geology of the floor is made of unconsolidated sediments of sand which increases the vibration of the earthquake and causes soil liquefaction.

88
Q

What were the short term responses to the earthquake in an LIC (Nepal)?

A

-Helicopters rescued many people caught in avalanches on Mount Everest and delivered supplies to villages cut off by landslides

-Half a million tents needed to provide shelter for the homeless

-Field hospitals set up to help support overcrowded main hospitals

89
Q

What were the long term responses to an earthquake in an LIC (Nepal)?

A

-Roads repaired and landslides cleared. Lakes formed by landslides were cleared to avoid flooding

-Thousands of homeless people to be re-housed and damaged homes repaired – Over 7000 schools to be repaired

-Stricter controls on building repairs

90
Q

What are the main reasons people live in hazardous regions?

A

-They’ve always lived there therefore moving means leaving jobs or families

-Volcanic soil is really fertile due to the minerals in the ash

-Volcanoes are tourist attractions meaning that people can work in the tourist industry

91
Q

What are the methods of reducing the effects of tectonic hazards?

A

-Monitoring
-Prediction
-Planning
-Protection

92
Q

How does monitoring earthquakes reduce the risk of them?

A

-Seismometers and lasers monitors the earth movements and can be useful in warning systems

-This will give enough warning before a large earthquake occurs

93
Q

How does monitoring a volcano reduce the risk?

A

-Scientists can tell the signs of a volcanic eruption
-These signs include tiny earthquakes, escaping gas and changes in the volcano’s shape

94
Q

How does prediction of earthquakes reduce the risk?

A

Earthquakes cannot be reliably predicted but scientists can forecast where they may occur by monitoring movement of tectonic plates

95
Q

How does prediction of volcanoes reduce the risk?

A

They can be predicted if scientists monitor them closely

96
Q

What are the methods of protecting people from earthquakes?

A

-Using reinforced concrete to build buildings that absorb the earthquake’s energy

-Existing buildings can be strengthened too with steel frames to reduce the likelihood of them collapsing

-Automatic shut off switches can tirn of gas and electricity supplies in order to prevent fires

97
Q

What are the methods to protect people from volcanic eruptions?

A

-Buildings can be strengthened so they’re less likely to collapse under the weight of ash

-Trenches and barriers have been used to divert lava from settlements however with little success

98
Q

What are the methods of planning in order to reduce risk of a natural event?

A

-Emergency services can prepare by practicing rescuing people from collapsed buildings

-People can be educated so they know what to do if a hazard occurs

-Governments can plan evacuation routes to get people out quickly and safely

99
Q

What is the life expectancy in Chile?

A

79.9 years

100
Q

What was the magnitude of the earthquake in Chile?

A

8.8

101
Q

What is the literacy rate in Chile?

A

96.4%

102
Q

What was the type of plate boundary the earthquake in Chile happened on?

A

Destructive plate margin

103
Q

What is the life expectancy in Nepal?

A

70 years

104
Q

What is the literacy rate in Nepal?

A

67.9%

105
Q

What was the magnitude of the earthquake in Nepal?

A

7.9

106
Q

What type of plate boundary did the earthquake in Nepal happen at?

A

Collision plate margin

Geography (7 decks)

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