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GEOGRAPHY > A: Natural/tectonic hazards > Flashcards

A: Natural/tectonic 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

What are the two types of natural hazards

A

Meteorological

Geological

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3
Q

What’s s geological hazard

A

Caused by land and tectonic processed

E’g. Volcanoes
Earthquakes
Landslides
Avalanches

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4
Q

What’s a meteorological hazard

A

Caused by weather and climate

Tropical storms 
Extreme weather
Heatwaves 
Cold spells 
Climate change
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5
Q

What’s a natural disaster

A

Natural hazard which has actually happened

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6
Q

What are extreme events

A

They do not pose any threat to human activity and there not counted as hazards (drought in an unhabitated desert)

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7
Q

What are different factors affecting hazard risk

A

Vulnerability
Capacity to cope
Nature of natural hazards

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8
Q

What is hazard risk

A

The probability that a natural hazard occurs

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9
Q

Explain vulnerability as a factor affecting hazard risk

A

More people in areas exposed to natural hazards the greater probability they will be affected by a natural hazard - hazard risk is higher

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10
Q

Explain capacity to cope as a factor affecting the hazard risk

A

Natural hazards have to affect human activities to count as a hazard. The better a population can cope with an extreme event, the lower the threat

HICs are better coping

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11
Q

Explain the nature of natural hazards as a factor affecting the hazard risk from a natural hazard

A

Type - the hazard risk from some hazards is greater than others
Eg tropical storms can be predicted and monitored giving people time to evacuate safely
But earthquakes happen very suddenly no warning

Frequency - some natural hazards occur more often than others increasing the hazard risk

Magnitude - more severe natural hazards cause greater effects than less severe natural hazards

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12
Q

What is the earths surface made of

A

Huge floating plates that are constantly moving called tectonic plates

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13
Q

What are the layers of the earth from the inner to the outer

A

Inner core
Outer core
Mantle
Crust

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14
Q

What’s the core of the earth like

A

Ball of solid (inner) and liquid (outer) iron and nickel

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15
Q

What’s the mantle like

A

Semi - molten rock that moves very slowly

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16
Q

What’s the crust like

A

Divided into slabs called tectonics plates (they float on the mantle) plates are made of two types of crust — continental and oceanic

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17
Q

What’s continental crust like

A

Thicker (30-50km) and less dense

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18
Q

What’s oceanic crust like

A

Thinner (5-10km) more dense

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19
Q

Why are the plates always moving

A

Because of convection currents in the mantle underneath the crust

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20
Q

What’s it called where plates meet

A

Plate margins or plate boundaries

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21
Q

What are the three types of plate margin

A

Destructive
Constructive
Conservative

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22
Q

What are destructive margins

A

Two plates move towards each other

Oceanic meets continental. Denser oceanic is late if rocked down into the mantle and destroyed

Often creates volcanoes and ocean trenches (very deep sections of the ocean floor where the oceanic plate goes down)

Two continental meet. Plates collide. Ground is golden and froorced up creating mountain range

E.g. West coast of South America

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23
Q

What are constructive margins

A

Two plates moving away from eachother
Magma (molten rock) rises from the mantle to fill the gap and cools, creating new crust

Eg mid Atlantic range

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24
Q

What are conservative margins

A

Two plates moving sideways past eachother or moving in the same direction at different speed

Crust isn’t created or destroyed

Eg along west coast of USA

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25
Q

What happens at destructive plate margins to form volcanoes

A

The oceanic plate goes under the continental plate because it is more dense.

The oceanic plate moves down into the mantle where it’s melted and destroyed

A pool of magma forms

The magma rises through cracks in the crust called vents

The magma erupts onto the surface (where it’s called lava) forming a volcano

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26
Q

What happens at constructive margins to form volcanoes

A

Magma rises up into the gap created forming a volcano

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27
Q

Where are volcanoes found

A

At destructive and constructive plate margins

28
Q

Where can some volcanoes also form?

A

Over parts of the mantle tht are really hot (hotspots)

Eg in Hawaii

29
Q

Which plate margins do earthquakes occur at?

A

All three

30
Q

What are earthquakes caused by

A

Tension that builds up at all three plate margins

31
Q

How’s an earthquake formed at destructive margins

A

Tension builds up when one plate gates stuck as it’s moving down past the other into the mantle

32
Q

How do earthquakes form at constructive margins

A

Tension build up along cracks within the plates as they move away from each other.

33
Q

How do earthquakes from at conservative margins

A

Tension build up when plates that are grinding past each other get stuck

34
Q

What exactly is the earthquake during tension build up?

A

The plates eventually jerk past each other sending out shock waves (vibrations) which is the earthquake

35
Q

What do shock waves do

A

Spread out from the focus - the point in the earth where the earthquake starts. Near the focus the waves are stronger and cause more damage

36
Q

What’s the epicentre?

A

Point on the earths surface straight above the focus in an earthquake

37
Q

What are earthquakes measured with

A

Linen magnitude scale

38
Q

What does the moment magnitude scale measure

A

The amount of energy released by an earthquake (called the magnitude)

It’s scale is logarithmic - so a magnitude 7 is ten times more powerful than a 6

39
Q

What is the magnitude of earthquakes which normally only cause slight damage to buildings although they can be worse in very built up areas

A

Magnitude 6 and below

40
Q

What size earth quakes cause major damage and deaths

A

Magnitude 7 and above

41
Q

Global distribution of earthquakes and volcanoes

A

…

42
Q

What are the two earthquakes we studied

A

Haiti

Japan

43
Q

When was the Haiti earthquake and what magnitude was it

A

January 2010

Magnitude 7

44
Q

What were the primary effects of Haiti earthquake

A

Prison was destroyed releasing 4,00 imprisoners

Buildings and homes destroyed
1-5 lost jobs

Injuries or killed from collapsed buildings and falling debris

45
Q

Secondary impacts of the Haiti earthquake

A

250,000 buildings were destroyed meant that people couldn’t work, roads became blocked disrupting any rescue attempts, trade difficult

Deaths of 250,000 people
Cholera spread
1.3mill lost there homes
Food rationed

46
Q

Where is Haiti?

A

19.19N 73.30W
72.5 longitude 18 Latitude
Caribbean

47
Q

Impacts only from Haiti earthquake

A 
Mag 7 
250000 dead 
Mercali 8 
No defences 
280,000 destroyed buildings 
4000 prisoners escaped 
1.1 billion damage 
1/5 lost jobs 
1300 schools damaged 
1.3mill homeless
48
Q

Impacts from Japan earthquake followed by tsunami 🌊

A 
Up to 12000 peiple dead 
Magnitude 8.9 
40m high wave 🌊 
£200 billion damage 
Had defences but we’re destroyed 
Nucleur meltdown 
Shifted earth on its axis 10cm 
Mercali 9 
Water reached 6 miles into land
49
Q

Impacts both on Japan and Haiti

A 
Caused by earthquakes 
Affected major cities 
Had help from other places 
Natural hazards 
Houses/buildings + livelihoods destroyed 
Occurred just if coast 
Diseases from dirty water (cholera)
50
Q

Haiti is a Lic what were its responses to its earthquake

A

3/4 damages buildings were inspected + repaired

200,000 peiple recieved cash or food for public work

World bank pledged $100 m to support reconstruction + recovery programmes

51
Q

Japan is a HIC what was its responses to its earthquake following with a tsunami

A

+ 100,000 soldiers deployed in search and rescue

Blankets food and water distributed

Specialised search and rescue teams flown in from overseas

Exclusion zone set up around fukushima nucleur plant and peiple were evacuated from the area

52
Q

What was the earthquake in Japan and when and where is the area

A

The Sendai earthquake in Japan 201

Sendai is in the continent of Asia in the stat Thoku

53
Q

What was the cause of the Sendai earthquake

A

Tremors were result of a violent uplift of the sea floor 80mikes off the coast of Sendai where the Pacific tectonic plate slides beneath the plate Japan sits on. Tens of miles off the coast is Sendai, where the Pacific tectonic plate slides beneath the plate Japan sits on. Tens

54
Q

Monitoring volcanoes and earthquakes

A

Volcanoes

Remote sensing - satellite detect heat and changes to the volcano shape

Seismicity - seismographs record earthquakes

Gas - instruments detect gases realeased as magma rises

Earthquakes - generally occur without warning there’s some evidence of changes in water pressure, ground deformation and minor tremors prior to earthquakes

55
Q

How can you predict volcanoes

A

Based on scientific monitoring
In 2010 an increase in earthquake activity beneath an ice cap in Iceland enabled scientists to make an accurate prediction about the eruptions that took place in March and April that year

56
Q

How can you predict earthquakes

A

Impossible to make accurate predictions about earthquakes due to the lack of clear warning signs

57
Q

How can you protect areas from earthquakes

A

Construct buildings and bridges to residue ground shaking

Reinforce concrete columns strengthened by steel force

Regular earthquake drills

Construct tsunami walls

58
Q

How can you protect an area from volcanoes

A

Earth bankments or explosives to divert lava flows away from property

59
Q

How can you plan for volcanoes

A

Hazard maps show sangered places

Used in planning to restrict certain land uses or to identify which areas need to be evacuated when an eruption is due

60
Q

How can you plan for an earthquake

A

Maps produces to show effects of an earthquake or identify those areas most at risk

High - value land uses a.g. Hospitals can be protected in these vulnerable areas

61
Q

Why do people still live in areas at risk from tectonic hazards

A

They’ve always lived there don’t wanna naive from friends and family

Employed in the area

Confident in support from government after a tectonic hazard

Think Severe hazards won’t happen again in area

Soil around volcanoes is fertile because it’s full of minerals from volcanic ash and lava attracts farmers

Volcanoes are tourist attractions - live/ work in tourist industry

62
Q

Management strategies can

A

Reduce the effects of tectonic hazards

63
Q

Monitoring tectonic hazards

A

Networks of seismometers and losers 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

Scientist can monitor the tell-tale signs that come before a volcanic eruption, such as tiny earthquakes, escaping gas, and changes in the shape of the volcano (eg. Bulges in the land where magma has built up under it) all mean an eruption is likely

64
Q

Predicting tectonic hazards

A

Earthquakes cannot be realisable predicted but by monitoring movement of tectonic plates scientists can forecast which areas should be prepared for one to occur

Volcanic eruptions can be predicted if the volcano is well-monitored, predicting when a volcano is going to erupt gives people time to evacuate this reduces number of injuries and deaths

65
Q

Predicting tectonic hazards

A

Buildings can be designed to withstand earthquakes eg by using materials like reinforced concrete or building special foundations that absorb an earthquakes energy
Existing buildings and bridges can be strengthened (eg by wrapping pillars in steel frames) so they’re less likely to collapse under the weight of falling ash or due to shaking from an earthquake
Automatic shutoff switches can be fitted that turn off gas and electricity supplies to prevent fires if an earthquake is detected by a monitoring system

66
Q

Planning for tectonic hazards

A

Future developments can be planned to avoid the areas most at risk from tectonic hazards
Emergency services can train and prepare for disasters eg by practising rescuing people from collapsed buildings or setting up shelters this will reduce deaths
People can be educated so that they know what to do if an earthquake or eruption happens
Governments can plan evacuation routes
Which reduces number of deaths by fires, pyroclastic flows or mudflows
Emergency supplies like blankets, clean water and food can be stockpiled, if a natural hazard is predicted the stockpiles can be moved close to affected areas potentially

GEOGRAPHY (9 decks)

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