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Geography > tectonic hazards > Flashcards

tectonic hazards Flashcards

1
Q

where do earthquakes occur?

A

at plate margins

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2
Q

how do the plates move at constructive plate margins

A

they move away from each other

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3
Q

how do the plates move at destructive margins

A

towards each other

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4
Q

where do volcanos occur

A

volcanoes occur in long belts that follow plate margins

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5
Q

at which type of plate margins can volcanoes occur

A
  • constructive and destructive
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6
Q

what is a hot spot

A

parts of the mantle which are really hot

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7
Q

how do the plates move at conservative plate margins

A

where the two plates are moving sideways past each other, or moving in the same direction but at different speeds

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8
Q

what is magma like at constructive margins?

A

very hot and fluid and lava will flow a long way before cooling - usually forms shield volcanoes

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9
Q

what happens at destructive margins

A

when an oceanic and continental plate meet, the denser oceanic plate sub ducts ( forced into the mantle) and destroyed creating magma - ocean trenches occur here

when two continental plates meet the ground is folded upwards making fold mountains

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10
Q

what happens at a constructive margin?

A

when the two plates move away from each other magma rises to fill the gap and cools, creating new crust.

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11
Q

what is the key information on the New Zealand ( HIC)

  • (5 things)
A
  • kaikoura ( new zealnd)
  • 14th of November 2016
  • GPD per captia - US 40,331
  • plate boundary - destructive and conservative - the pacific plate sub ducts beneath Australian plate to the north and sliding past in the south
  • 7.8 magnitude
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12
Q

what were the primary affects of new zealand eatrthquake

HIC

A
  • 2 people died
  • 50 people were injured
  • tens of thousands of houses were destroyed and damaged
  • 60 people needed emergency housing
  • US 8.5 billion - cost of damaged
  • over 200km of road destroyed
  • communications,water and power supplies were cut off
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13
Q

what were the secondary affects of the New zealand earthquake

A
  • triggered up to 100,000 land slides which blocked major roads and rail routes
  • a major landslide blocked clarence river leading to flooding and evacuation of 10 farms
  • generated tsunami with wave of 5 m
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14
Q

what were the immediate responses for the New Zealand earthquake?

A
  • tsunami warning - residents of coastal areas told to go to higher ground
  • people housed in emergency centres
  • 200 vulnerable people evacuated from kaikoura by helicopter
  • power restored to most places
  • temporary water supplies set up
  • international warships were sent with supplies e.g food medicine, portable toilets
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15
Q

what were the long term Reponses of the New Zealand earthquake

A
  • most road are rails were opened within 2 years
  • the kaikoura mayoral earthquake relief fund was set up to support residents who couldn’t afford basic supplies
  • 5.3 million of funding was provided by kaikouras district council to help with rebuilding
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16
Q

name the 3 layers of the earth

A

the core, the crust and the mantle

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17
Q

Tectonic plates move according to the movements below in the _______

A

mantle

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18
Q

where do convection currents happen

A

in the upper mantle

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19
Q

What are the potential products of volcanic eruptions?

A
  • gas
  • ash
  • lava
  • pyroclastic flows
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20
Q

what is the key information of the Nepal earthquake 2015

A
  • 25th April 2015
  • 7.8 magnitude
  • destructive plate margin
  • the indo Australian plate subducts beneath the Eurasian plate
  • GDP - US 690
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21
Q

what were the primary affects of the Nepal 2015 earthquakes

A
  • 9000 people died
  • 20000 injured
  • 4 million people left homeless
  • overall cost of US 5 billion
    electricity and water effected
  • roads and bridges were destroyed
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22
Q

what were the secondary effects of the Nepal 2015 earthquake?

A
  • land slides + avalanche causing road blockages
  • avalanche in mount Everest kill 18 people
  • landslide blocked river causing river to flood making people evacuate
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23
Q

what were the immidiate responses of the Nepal earthquake 2015?

A
  • search and rescue
  • half a million tents to provide shelter to the homeless
  • financial aid
  • feild hospitals
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24
Q

what evidence is there that Nepal is poorer than New Zealand?

A

the HDI and GDP shows that nepal is lower than New Zealand in the rankings.

25
Q

why was such a vast area of Nepal affected?

A

the earthquake in Nepal triggered landslides and avalanches which went on for miles increasing the amount of land that was affected by the earthquake

26
Q

why do people choose to live in hazardous areas?

A
  • poverty
  • they might not be aware
  • favourable areas ( coasts - ports)
  • volcanoes can bring benefits - fertile soil
  • earthquakes and volcanoes dont happen often so people do not worry about them
  • they have always lived there
  • wealthy countries might have effective monitoring which reduces risk
27
Q

how can we reduce the risk of hazards?

A
  • monitoring - scientific equipment to detect warning
  • planning - avoiding places at risk
  • protection - building that will withstand
  • prediction - historical evidence
28
Q

what are some warning signs of volcanoes?

A
  • steam erupting
  • heat melts the snow
  • gases from the rising magma
29
Q

what are different types of monitoring?

A
  • remote sensing - satellites that detect heat
  • seismicity - seismographs
30
Q

what two types of crust are plates made up of?

A
  • continental - thicker and less dense
  • oceanic - thinner and more dense
31
Q

why do plates move

A

because of convection currents in the mantle

32
Q

what are the places where plates meet called

A

plate margins or plate boundaries

33
Q

what are the three different types of plate margins

A
  • destructive
  • constructive
  • conservative
34
Q

give an example of a conservative plate margin

A

San Andreas Fault
the pacific plate is moving in the same direction as the north american plate but faster

35
Q

give an example of a destructive plate margin

A
  • west coast of south america
  • Nazca plate sub ducts under south american plate creating the Atacama trench
36
Q

give an example of a constructive plate margin

A
  • the movement of the Eurasian plate and north american plate away from one another creates the mid Atlantic ridge
37
Q

how do volcanoes occur at destructive plate margins

A
  • denser oceanic plate moves down into the mantle where it melts
  • a pool of magma forms which rises through the cracks in the crusts called vents
  • the magma erupts forming a volcano
38
Q

how do volcanoes occur at constructive plate margins

A
  • the magma rises into the gap created by the plates moving apart creating a volcano
39
Q

which plate margins do earthquakes occur at?

A

all three of them

40
Q

what are earthquakes caused by?

A

by the tension that builds up at the plate margins

41
Q

how do earthquakes occur at destructive plate margins

A
  • tension builds up when one plate gets stuck as it moves across the other
42
Q

how do earthquakes occur at constructive plate margins

A

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

43
Q

how do earthquakes occur at conservative plate margins

A

tension builds up when plates that are grinding past eachother get stuck

44
Q

plates eventually jerk past eachother, sending out ______ ____. these vibrations are the ____________

A

shock waves
earthquake

45
Q

where are shock waves spread out from

A

the focus

46
Q

what is the focus

A

the point in the earth where the earthquake starts
- waves are stronger near the focus and cause more damage

47
Q

what is the epicentre

A

the point on the earths surface straight above the focus

48
Q

how can we monitor earthquakes

A
  • seismometers and lasers monitor earth movements and can give a small amount of warning
49
Q

how can we monitor volcanos

A
  • tiny earthquakes
  • escaping gas
  • changes in shape of a volcano
50
Q

how can we predict earthquakes

A

they cant be reliably predicted but scientists can forecast where they may occur by monitoring the movement of plates

51
Q

hwo can we predict volcanos

A

is scientists monitor volcanos closley

52
Q

how can we use protection to reduce the effects of earthquakes

A
  • new buildings can sue reinforced concrete that absorb an earthquakes energy
  • existing buildings and bridges can be strengthened
  • automatic shut off switches can turn off gas and electricity to stop fires
53
Q

how can we use protection to reduce the effects of volcano

A
  • buildings strengthened so they are less likely to collapse under the strength for ash
  • trenches and barriers can be used to try and divert lava away from buildings and settlements
54
Q

what methods can be sued to plan fro volcanoes and earthquakes

A

-emergency services can prepare by practising e.g practise rescuing people from collapsed building
- people can be educated to know what to do in the event of a hazard
- government plan evacuation routes
- emergency supplies can be stockpiled

55
Q

What type of hazard are earthquakes and volcanoes examples of?

A

geological

56
Q

What factors affect the severity of natural hazards?

A

frequency
predictability
magnitude

57
Q

what are the two layers of the core

A

inner metallic core - solid
outer outer - liquid

58
Q

what are the characteristics of volcanoes at destructive plate margins?

A
  • highly explosive
  • produces alot of gas
  • produces alot of lava
59
Q

What do we call the event when a volcano erupts, produces lots of ash, and blocks the sun?

A

a volcanic winter

Geography (8 decks)

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