Unit 1 Flashcards

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1
Q

What is a natural hazard?

A

a natural hazard is a natural process which could cause death, injury or disruption to humans, or destroy property and possessions.

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2
Q

What is a natural disaster?

A

a natural disaster is a natural hazard that has actually happened

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3
Q

What are geological hazards?

A

geological hazards are caused by land and tectonic processes

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4
Q

what are meteorological hazards?

A

meteorological hazards are caused by weather and climate

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5
Q

example of geological hazards

A

volcanoes, earthquakes, landslides, avalanches

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6
Q

example of meteorological hazards

A

tropical storms, other extreme weather such as; heatwaves, cold spells

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7
Q

what is hazard risk

A

hazard risk is the probability of people being affected by a hazard in a particular area

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8
Q

what are the factors that affect hazard risk?

A
  1. vulnerability
  2. capacity to cope
  3. nature of natural hazard
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9
Q

what does vulnerability mean as a factor that affects hazard risk?

A

the more people in an area exposed to natural hazards, the greater the probability they will be affected by a natural hazard.

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10
Q

what does capacity to cope mean as a factor that affects hazard risk?

A

the better the population can cope with an extreme event, the lower the risk of them being severely affected.

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11
Q

examples of vulnerability

A

Bangladesh has a high population density on a flood plain, therefore very vulnerable to flooding.

Naples, Italy is at the base of a volcano.

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12
Q

example of capacity to cope

A

HICs are better able to cope with flooding because they can afford to build flood defences and evacuate people.

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13
Q

nature of natural hazards

A
  1. type
  2. frequency - natural hazards that occur more often may carry a higher risk.
  3. magnitude - more severe natural hazards tend to have the greatest affects.
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14
Q

why does the type of natural hazard affect the risk?

A

the risk from some hazards is greater than others.

e.g. Tropical storms can be predicted and monitored, giving people time to evacuate.
Earthquakes happen very suddenly, with no warning, so it’s much harder to protect people.

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15
Q

What does primary effect mean

A

the primary affect of natural disasters are the immediate impacts caused by the hazard itself

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16
Q

what does secondary effect mean

A

the secondary effects happen later on, often as a result of the primary effects.

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17
Q

example of primary effects.

A
  • buildings and roads are destroyed by earthquakes, volcanic eruptions or tropical storms.
  • people are injured or killed
  • crops and water supplies can be damaged or contaminated
  • electricity cables, gas pipes, and communication networks can be damaged, cutting off supplies.
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18
Q

example of secondary effects.

A
  • the initial hazard can trigger other hazards e.g. earthquakes can trigger tsunamis.
  • aid and emergency vehicles can’t get through because of blocked roads or bridges ( can cause more deaths)
  • a shortage of clean water + lack of proper sanitation makes it easier for disease to spread.
  • food shortages can occur if crops are damaged
  • country’s economy can be weakened
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19
Q

example of immediate responses

A
  1. evacuate people (before hazard occurs if possible)
  2. treat the injured and rescue anyone cut off by damage to roads or bridges.
  3. recover dead bodies to prevent disease spreading.
  4. provide temporary supplies of electricity and gas if regular supplies have been damaged.
  5. provide food, drink and shelter to people without homes.
  6. foreign governments or charities may send aid workers, supplies or financial donations.
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20
Q

example of long term responses

A
  1. repair homes or rehouse people who lost their homes.
  2. repair or rebuild buildings, roads, railways and bridges.
  3. reconnect broken electricity, water, gas and communication connections.
  4. improve forecasting, monitoring and evacuation plans.
  5. improve building regulations so buildings can withstand similar hazards in the future.
  6. boost economic recovery
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21
Q

about tectonic plates

A
  1. float on the mantle layer.
  2. plates are made up out of two types of crust:
    - continental crust, thicker (30-50km) and less dense.
    - oceanic crust, thinner (5-10km) and more dense.
  3. The plates are moving because of convection currents in the mantle.
  4. The places where plates meet are called plate margins/ boundaries.
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22
Q

what are the three types of plate margins?

A
  1. destructive margins
  2. constructive margins
  3. conservative margins
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23
Q

what are destructive margins?

A
  • two plates moving towards eachother
  • an oceanic plate meets a continental plate, the denser oceanic plate is subducted, and destroyed, creating gas-rich magma.
  • volcanoes and ocean trenches
  • two continental plates meet, the ground is folded upwards, creating fold mountains.
24
Q

example of destructive margin

A

along the west coast of South America, the oceanic Nazca plate is being subducted beneath the continental South American plate, creating the Atacama Trench

25
Q

what are constructive margins

A
  • two plates are moving away from eachother.
  • Magma rises from the mantle to fill the gap and cools, creating new crust
  • volcanoes
  • earthquakes
26
Q

example of constructive margins

A

the movement of the Eurasian plate and the North American plate away from one another is forming the mid-Atlantic ridge.

27
Q

what are conservative margins?

A
  • two plates moving sideways past eachother or are moving in the same direction but at different speeds.
  • crust isn’t created of destroyed.
  • earthquakes
28
Q

example of conservative margins

A

at the San Andreas Fault, the Pacific plate is moving in the same direction as the North American plate but faster

29
Q

what way do destructive margins move

A

towards eachother

30
Q

what way do constructive margins move

A

away from eachother

31
Q

what way do conservative margins move

A

sideways past eachother, or the same direction at different speeds

32
Q

how volcanoes are formed at destructive margins

A

the denser oceanic plate moves down into the mantle, where it melts. A pool of magma forms, which then rises through cracks in the crust called vents. The magma is erupts, forming a volcano.

33
Q

how volcanoes are formed at constructive margins

A

the magma rises up into the gap created by the plates moving apart, forming a volcano.

34
Q

volcanoes

A
  • destructive and constructive margins
  • some volcanoes also form over parts of the mantle that are really hot ( called hotspots) e.g. in Hawaii
  • when a volcano erupts, it emits lava and gases. Some volcanoes emit lots of ash, which can cover land, block out the sun and form pyroclastic flows.
35
Q

what are pyroclastic flows?

A

pyroclastic flows are super-heated currents of gas, ash and rock.

36
Q

how are earthquakes formed at destructive plate margins ?

A

tension builds when one plate gets stuck as it moves past the other.

37
Q

how are earthquakes formed at constructive margins?

A

tension builds along the cracks in the plates as they move away from each other.

38
Q

how are earthquakes formed at conservative margins?

A

tension builds up when plates that are grinding past each other gets stuck.

39
Q

how earthquakes happen

A
  1. tension builds up at plate margins
  2. the plates eventually jerk past each other, sending out shock waves. These vibrations are the earthquake.
  3. The shock waves are spread out from the focus - the point in the Earth where the earthquake starts. The waves are stronger near the focus and cause more damage.
  4. The epicentre is the point on Earth’s surface straight above the focus.
  5. Earthquakes are measured using the moment magnitude scale.
40
Q

measuring earthquakes

A
  • The moment magnitude scale measures the amount of energy releases by an earthquake.
  • It is a logarithmic scale ( magnitude 7 earthquake would cause ten times as much ground shaking as a magnitude 6 earthquake).
  • Earthquakes of magnitude 6 and below normally cause slight damage to buildings ( can be worse in built up areas)
  • Earthquakes of magnitude 7 and above cause major damage and deaths.
41
Q

facts about the new zealand earthquake

A

Place: Kaikoura, new zealand.
Date: 14th nov, 2016.
GDP per capita: US $40,331.
Plate Margin: Destructive and conservative - the Pacific plate is subducting beneath the Australian plate to the north, and sliding past it to the south.
Magnitude: 7.8

42
Q

Primary effects of New Zealand earthquake

A
  • 2 people died and over 50 people injured.
  • tens of thousands of homes were damaged and some destroyed
  • 60 people needed emergency housing.
  • The total cost of damage was around US $8.5 billion.
  • over 200Km of road and over 190Km of rail line were destroyed.
  • Communications, water, sewerage and power supplies were cut off.
43
Q

Secondary effects of New Zealand earthquake

A
  • Earthquake triggered up to 100,000 landslides which blocked major road and rail routes.
  • A major landslide blocked the Clarence River, leading to flooding and evacuation of 10 farms.
  • The earthquake generate a tsunami with waves of around 5m, leaving debris up to 250m inland.
44
Q

facts about nepal earthquake

A

Place: Gorkha, Nepal.
Date: 25th April, 2015
GDP per capita: US $690
Plate margin: Destructive - the Indo-Australian plate is being subducted beneath the Eurasian plate.
Magnitude: 7.8

45
Q

primary effects of Nepal earthquake

A
  • Around 9000 people died and more than 22,000 were injured.
  • An estimated 800,000 buildings were damaged or destroyed.
  • 4 million people were left homeless.
  • The cost of damages was over US $5 billion.
  • Roads and bridges were destroyed.
  • Water tanks and pipes were destroyed leaving 2 million people without access to clean water and sanitation.
46
Q

secondary effects of Nepal earthquake

A
  • The earthquake triggered avalanches on Mount Everest which killed 18 people.
  • Many mountains roads were blocked by landslides, preventing emergency aid from reaching remote areas.
  • A lack of clean water caused outbreaks of typhus, which killed at least 13 people.
47
Q

immediate responses of New Zealand earthquake

A
  • A tsunami warning was issued quickly, and residents of coastal areas were told to move to higher ground.
  • Hundreds of people were housed in emergency shelters and community centres.
  • 200 of the most vulnerable people were evacuated from Kaikoura by helicopter within 24 hours.
  • Power was restored to most places within a few hours. Temporary water supplies were set up.
  • International warships were sent to Kaikoura with supplies such as food, medicine and portable toilets.
48
Q

long term responses to New Zealand earthquake

A
  • $5.3 million of funding was provided by the Kaikoura District Council to help with rebuilding the towns water systems and harbour.
  • Most raid and rail routes were repaired and reopened within 2 years.
  • The Kaikoura Mayoral Earthquake Relief Fund was set up to help residents who couldn’t afford basic supplies, and donations were received from around the world.
  • By March 2017, a permanent water main had been laid in Kaihoura. The new pipe was designed to move with any future earthquakes so it won’t break.
49
Q

immediate responses of Nepal earthquake

A
  • India and China sent teams to help residents rescue people trapped by debris, but a lack of tools and machinery slowed down rescue efforts.
  • People tried to recover the dead and treat the injured, but damaged roads made it hard for emergency workers and aid to get through.
  • Charities such as Oxfam provided medicine, food and temporary water supplies.
  • The Red Cross set up emergency shelters for 130,000 families who had lost their homes.
50
Q

long term responses of Nepal earthquake

A
  • The world Bank Group financed $500 million worth of projects to build earthquake-resistant housing, and repair roads and irrigation systems. Some projects are still ongoing.
  • The road from Nepal into Tibet was reopened 2 years after the earthquake, but many other routes remain damaged.
  • Many heritage sites were reopened in June 2015 to encourage tourists back to the area.
  • Water supply is being restored, but two years after the event, people still didn’t have access to clean water.
  • NGOs are working with residents to increase their resilience to disasters, for example by providing alternative energy sources.
51
Q

Why do people live in areas at risk of tectonic hazards?

A
  • Cant afford to move.
  • Very fertile soil.
52
Q

what is monitoring

A
  1. Earthquakes - seismometers are lasers monitor earth movements, and can be used in early warning systems to give a small but vital amount of warning before a large earthquake occurs.
  2. volcanic eruptions - scientists can monitor the tell- tale signs that come before an eruption, such as earthquakes, escaping gas, and changes in the shape of a volcano.
53
Q

prediction

A
  1. earthquakes - cannot be reliably predicted, but scientists can forecast where they may occur by monitoring the movement of tectonic plates.
  2. volcanic eruptions - can be predicted if scientists monitor volcanes closely.
54
Q

protection

A
  1. earthquakes - new buildings can use reinforced concrete that absorb an earthquakes energy. Existing buildings and bridges can be strengthened with steel frames so they’re less likely to collapse. Automatic shut-off switches can turn off gad and electricity to prevent fires.
  2. Volcanic eruptions - buildings can be strengthened so that they’re less likely to collapse under the weight of ash. Trenches and barriers have been used to try divert lava away from settlements, but with little success.
55
Q

planning

A
  1. future developments can avoid high- risk areas.
  2. emergency services can prepare e.g. practising rescuing people from collapsed buildings.
  3. people can be education so that they know what to do incase of a hazard.
  4. governments can plan evacuation routes to get people away quickly and safely .
  5. Emergency supplies like blankets, clean water and food can be stockpiled.