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A level Geography > Hazards > Flashcards

Hazards Flashcards

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1
Q

what are geophysical hazards?

A

volcanic and seismic hazards related to the lithosphere

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2
Q

what are atmospheric hazards?

A

includes tropical storms, droughts and tornadoes . Hazards related to the atmosphere

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3
Q

what are hydrological hazards?

A

involve flooding and are related to the hydrosphere

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4
Q

what is risk?

A

the potential for loss

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5
Q

what is vulnerability?

A

the exposure to hazards and ability to cope with them

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6
Q

what is resilience?

A

the degree to which a population or environment can absorb a hazardous event

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7
Q

what are features that increase resilience?

A
  • emergency evacuation, rescue and relief systems in place
  • helping each other/ community
  • having a hazard resistant design or land use planning
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8
Q

why is it difficult to compare impacts between countries?

A
  • the physical nature of the event is different
  • the socio-economic characteristics of places are different
  • economic costs in developed economies are large, but they are less costly in developing countries
  • deaths in developed countries are lower
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9
Q

what are influences of vulnerability?

A

inequality of access to education, housing, healthcare, income

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10
Q

what is the fatalist approach to a hazard?

A

where people accept the risk and choose to do little about it. More likely in developing countries/LICs

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11
Q

what is a destructive plate margin?

A

when oceanic plate slides beneath continental plate and crust is destroyed as one goes beneath the other towards the subduction zone

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12
Q

what is a conservative plate margin?

A

plates sliding past each other horizontally

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13
Q

what is a constructive plate margin?

A

plates move apart from each other

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14
Q

characteristics of oceanic plate?

A
  • high-density
  • made of basaltic rock
  • 7-10km thick
  • subduct beneath other plates
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15
Q

characteristics of continental crust?

A
  • 25-75km thick
  • less dense
  • granite- do not sink
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16
Q

what is an island arc?

A
  • form at destructive subduction boundaries, when the descending plate melts and material rises towards the surface as magma
  • when plutons of magma reach the surface they form volcanoes which may erupt offshore, causing al ine of volcanic islands eg. Marianas trench
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17
Q

what are volcanoes?

A
  • found at constructive and destructive subduction boundaries, where the melted plate rises to the surface
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18
Q

what are deep sea trenches?

A
  • found at destructive subduction boundaries, where oceanic subducts under continental eg. Marianas trench
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19
Q

what are fold mountains?

A
  • destructive subduction and destructive collision boundaries
  • as plates move together, sediment in the sea is pushed up into folds between them
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20
Q

what are rift valleys?

A
  • formed at constructive plate boundaries where 2 continental plates pull apart
  • as the crust thins it is heated forming cracks
  • when an area of crust drops down between two parallel faults this is a rift valley
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21
Q

what are ocean ridges?

A
  • formed at constructive boundaries where 2 oceanic plates pull apart
  • as pressure is reduced the semi-molten magma of the mantle melts and rises up into the gap between the plates forming a ridge eg. mid-Atlantic
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22
Q

what is a hazard?

A

a natural event that has the potential to threaten both life and property

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23
Q

what is the distribution of hazards like?

A

uneven- some areas of the world are at low risk some are at high risk
- distribution of earthquakes is uneven- pacific ring of fire mainly

24
Q

what are hotspots?

A
  • a hot mass or rising heat under a weakness in a plate

- magma rises to the surface through the weaknesses

25
Q

what is the lithosphere?

A

the crust and upper mantle (80-90km) which form the tectonic plates

26
Q

what is the mantle?

A

the mantle is a semi molten body of rock between the earth’s crust and its core

27
Q

what is the core?

A

the central part of the earth

28
Q

what is the asthenosphere?

A

lower part of the mantle

29
Q

what is gravitational sliding?

A

elevated altitudes of oceanic crust at ridges at divergent plate boundaries- creating a slope down which oceanic plates slide

30
Q

what is sea floor spreading?

A
  • in the 1960s, there was a discovery of magnetic stripes in the oceanic crust of the seabed
  • paleomagnetic signals from past reversals of the Earth’s magnetic field prove that new crust is created by the process of seafloor spreading at mid-ocean ridges
31
Q

what is slab pull?

A

at convergent boundaries, high density ocean floor is being dragged down by a downward gravitational force beneath the adjoining continental crust

32
Q

what did Wegner say about continental drift?

A

1912- said that our now separate continents had once been joined together as super continents eg. Pangea

33
Q

what happens at a collision margin?

A

characterised by the meeting of two continental landmasses resulting in the formation of a fold mountain belt

34
Q

what happens at a transform margin?

A
  • no volcanic activity
35
Q

what is pyroclastic and ash fallout?

A
  • any material that has been ejected from a volcano and has travelled through the air and fallen onto earth
36
Q

what are pyroclastic flows/nuees ardentes?

A
  • currents of hot ash, lava and gas that move downhill during an eruption
37
Q

what are lahars?

A
  • if volcanic ash or lava mixes with water lahars (mudflows) form
  • fast moving flows of volcanic material and water
38
Q

what is tephra?

A
  • rock fragments that are ejected from the eruption
39
Q

how can you predict volcanic eruptions?

A
  • gas emissions
  • seismic waves
  • thermal images (magma)
  • volcanic swelling
40
Q

what is a jokulhlaup?

A

the name of the flooding that happens when glaciers or ice caps melt

41
Q

what are immediate responses to an eruption?

A
  • aid
  • evacuation
  • warnings and monitoring
  • temporary infrastructure
42
Q

what are the long term responses to volcanic eruptions?

A
  • education
  • improve local economy
  • rebuild infrastructure
  • relocation
43
Q

what are effective mitigation and adaptation strategies?

A
  • physical defences
  • land-use and buildings- resistant infrastructure- land use zoning
  • community preparedness and education
  • modifying loss- aid/compensation
44
Q

what is the focus?

A

where the pressure is released underground and where the energy radiates from

45
Q

what is the epicentre?

A

the point above ground directly above the focus

46
Q

what are the 3 types of EQ?

A
  • shallow focus-0-70km beneath surface
  • deep focus- 70-700km- less damaging
  • underwater EQs- move the seabed causing water to be displaced
47
Q

what are the primary hazards of EQs?

A
  • ground shaking

- crustal fracturing- earth splitting apart

48
Q

what are the secondary hazards of EQs?

A
  • landslides
  • liquefaction
  • tsunamis
49
Q

how is a tsunami created?

A

the seabed is displaced vertically- this motion displaces a large volume of water in the ocean column which then moves outwards from the point of displacement

50
Q

what is a collision plate margin?

A
  • two continental plates move together= fold mountains
51
Q

how do you mitigate against the impact of EQ’s?

A
  • physical defences
  • education
  • land-use and buildings
  • EQ proof buildings
  • alert system
52
Q

what causes a tropical storm?

A
  • warm air rising from oceans with over 27° will create pockets of low pressure. These will draw in warm air from the surrounding area
  • if this occurs between 5-20° N or S of equator the Coriolis force means these systems will rotate
  • as more warm air is drawn in, they grow into tropical depressions and eventually tropical storms
53
Q

what is the structure of a tropical storm?

A
  • 200-700km wide with rotating spiral of clouds
  • eye usually 10-15km in diameter- calm
  • strong conditions in eye wall
  • energy dissipates over ground
54
Q

what hazards are associated with tropical storms?

A
  • heavy rainfall
  • storm surges
  • strong winds
55
Q

how are storms measured?

A

on the saffir-simpson scale- largest storms reaching category 5

56
Q

how frequent are tropical storms?

A
  • around 100 tropical storms form in the Atlantic each year with 5.9 becoming hurricanes
  • frequency increase linked to global warming

A level Geography (17 decks)

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