Natural Hazards Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is a natural hazard?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a natural disaster?

A

A natural hazard that has in fact happened and injures 100 people or killed 10 people or causes $16 million worth of damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a natural event?

A

Occurs in remote areas that are away from people and property

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why are some extreme events not counted as hazards?

A

Because they do not pose any threat to human activity. For example, an avalanche in Antarctica.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the two main types of hazard?

A

1) Geological hazards
2) Meteorological hazards

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a geological hazard?

A

Hazards that are caused by land and tectonic processes. They include volcanoes and earthquakes, landslides and avalanches.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a meteorological hazard?

A

Hazards caused by weather and the climate. They include tropical storms, heatwaves, cold spells, etc.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a hazard risk?

A

The probability of people being affected by a hazard in a particular area.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the 3 factors that can affect hazard risk?

A

1) Vulnerability
2) Capacity to cope
3) Nature of Natural hazards

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How can vulnerability affect hazard risk?

A

1) The more people that are in an area exposed to natural hazards, the greater the probability they will be affected by a natural hazard.
2) For example, an area with a high population density on a flood plain (like Bangladesh) is very vulnerable to flooding caused by extreme weather.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How can the capacity to cope affect hazard risk?

A

1) The better a population can cope with an extreme event, the lower the risk of them being severely affected.
2) For example, higher income countries are better able to cope with flooding because they can afford to build flood defences and evacuate people.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How can the nature of natural hazards affect hazard risk?

A

1) Type - the risk from some hazards is greater than others (e.g. tropical storms can be predicted and monitored giving people time to evacuate but earthquakes happen very suddenly so it’s much harder to protect people).
2) Frequency - natural hazards that occur more often may carry a higher risk.
3) Magnitude - more severe natural hazards tend to have the greatest effects.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the primary effects of natural disasters?

A

The immediate impacts caused by the hazard itself:
1) Buildings and roads destroyed by earthquakes
2) People are injured or killed (e.g. when buildings collapse)
3) Crops and water supplies can be damaged or contaminated
4) Electricity cables, gas pipes and communication networks can be damaged cutting off supplies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the secondary effects of natural disasters?

A

The result of the primary effect:
1) The initial hazard can trigger other hazards (e.g. earthquakes can trigger tsunamis)
2) Aid and emergency vehicles can’t get through because of blocked roads or bridges - this can cause more deaths
3) A shortage of clean water and a lack of proper sanitation makes it easier for disease to spread
4) Food shortages can occur if crops are damaged, livestock are killed or supply lines are blocked.
5) The country’s economy can be weakened - damage to businesses can cause unemployment, and the reconstruction can be very expensive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are immediate responses to a natural disaster?

A

1) Evacuate people (before the hazard occurs if possible)
2) Treat the injured and rescue anyone cut off damage to roads or bridges
3) Recover dead bodies to prevent disease spreading
4) Provide temporary supplies of electricity and gas if regular supplies of 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.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are long-term responses to a natural disaster?

A

1) Repair homes or rehouse people who have 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 that buildings can withstand similar hazards in the future
6) Boost economic recovery (e.g. by promoting tourism)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the Earth’s crust divided into?

A

Slabs called tectonic plates

18
Q

What are crusts the 2 crusts? What are the differences?

A

1) Continental crust is thicker (30-50km) and less dense (and usually older)
2) Oceanic crust is thinner (5-10km) and more dense (and younger because it is constantly destroyed)

19
Q

Why do the tectonic plates move?

A

Because of convection currents in the mantle.

20
Q

What are the places where the plates meet called?

A

Plate margins or plate boundaries.

21
Q

What are the 3 types of plate margin?

A

1) Destructive
2) Constructive
3) Conservative

22
Q

What happens at the destructive margins?

A

Where two plates move towards each other
1) Where an oceanic and continental plate meet - the denser oceanic plate subducts underneath the continental plate into the mantle where it is destroyed creating gas-rich magma
2) Where two of the same plates meet - the ground is folded upwards (as they both have the same density) creating fold mountains
Example: along the west coast of South America, the oceanic plate Nazca plate is being subducted beneath the continental South American plate, creating the Atacama Trench

23
Q

What happens at the constructive margins?

A

Constructive margins are where two plates move away from each other. Magma rises from the mantle to fill the gap and cools creating new crust.
Example: the movement of the Eurasian plate and the North American plate away from one another is forming the mid-Atlantic ridge.

24
Q

What happens at the conservative margins?

A

Where two plates move sideways past each other, either in the same direction at different speeds or in opposite directions.
Example: at the San Andreas Fault, the Pacific plate is moving in the same direction as the North American plate but faster.

25
Q

What occurs where plates meet?

A

Volcanoes and earthquakes.

26
Q

What margins do volcanoes occur at? Explain how?

A

1) At destructive margins - 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 (called lava when it reaches the surface) erupts forming a volcano.
2) At constructive margins - the magma rises up into the gap created by the plates moving apart forming a volcano

27
Q

When do volcanoes not occur at margins?

A

Some volcanoes form over parts of the mantle that are really hot called hotspots (e.g. Hawaii)

28
Q

What happens when a volcano erupts?

A

It emits lava and gases. Some volcanoes emits lots of ash which can cover land and block out the sun and form pyroclastic flows (super-heated currents of gas, ash and rock).

29
Q

What margins do earthquakes occur at? Explain how?

A

1) Destructive margins - tension builds when one plate gets stuck as it moves past the other
2) Constructive margins - tension builds along cracks in the plates as they move away from each other
3) Conservative margins - tension builds up when plates that are grinding past each other get stuck

Then the plates eventually jerk past each other, sending out shock waves - these vibrations are the earthquake. The shock waves 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. The epicentre is the point on the Earth’s surface straight above the focus.

30
Q

How are earthquakes measured?

A

Using the moment magnitude scale:
1) The moment magnitude scale measures the amount of energy released by an earthquake (called the magnitude)
2) It is a logarithmic scale - this means a magnitude of 7 would cause ten times as much ground shaking than a magnitude 6 earthquake.
3) Earthquakes of magnitude 6 an below normally only cause slight damage to buildings, although they can be worse in very built up areas
4) Earthquakes of magnitude 7 an above can cause major damage and deaths

31
Q

What factors make disasters more likely?

A

1) Population - megacities with over 10 million inhabitants
2) Location - when countries are closer to plate margins, making them more susceptible (likely) to (experience) earthquakes
3) Poverty - exposure as they tend to live in vulnerable areas as it’s cheaper

32
Q

Describe the Earth’s layers?

A

THE CRUST: 65km deep - split into two types of crust (oceanic and continental)
THE MANTLE: 2870km thick (makes up half of the Earth’s structure) - made of dense, molten rock which is around 1000-4000°C
THE OUTER CORE: 2400 km deep - made of liquid iron and nickel and reaches 4000-5000°C
THE INNER CORE: 1200 km deep - made from solid nickel and iron and reaches a temperature up to 5,500°C - there is radioactive decay from materials uranium and thorium

33
Q

What is a convection current?

A

The movement of a fluid caused by a difference in temperature or density

34
Q

What are the 4 ways of preparing for a natural hazard?

A

1) Monitoring - detecting and recording physical changes and warning signs of a hazard
2) Planning - having systems in place such as evacuation routes so that if a hazardous event occurs the population is prepared in advanced
3) Prediction - using monitoring as well as historical trends and computer-based modelling to predict when a hazardous event might occur
4) Protection - increasing the resistance of a population to natural hazards by physically designing things that will withstand natural hazards

35
Q

Why do people live close to volcanoes?

A

1) Cannot afford to move
2) They’ve always lived there and moving can mean leaving their job or family
3) In richer countries, effective monitoring and evacuation plans to minimise risk

36
Q

How do people monitor earthquakes?

A

By seismometers and 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

37
Q

How do people monitor volcanic eruptions?

A

Scientists can monitor the tell-tale signs that come before an eruption, such as tiny earthquakes, escaping gas, and changes in the shape of a volcano

38
Q

How do people predict earthquakes?

A

Cannot be reliably predicted, but scientists cab forecast where they may occur by monitoring the mivement of tectonic plates

39
Q

How do people predict volcanic eruptions?

A

Can be predicted if scientists monitor volcanoes closely

40
Q

How do people protect themselves from earthquakes?

A

New buildings can use reinforced concrete that absorb an earthquake’s 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 has and electricity supplies to prevent fires.

41
Q

How do people protect themselves from volcanic eruptions?

A

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 to divert lava away from settlements.

42
Q

How do people plan for earthquakes and volcanic eruptions?

A

1) Future developments can avoid high-risk areas
2) Emergency services can prepare (e.g. by practising rescuing people from collapsed buildings)
3) People can be educated so that hey know what to do in the event 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