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Hazards Flashcards

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1
Q

What is a natural hazard?

A

Natural hazard = A natural event with the potential to cause harm to people and to property

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2
Q

What is a natural disaster?

A

A natural disaster = The realisation of a natural hazard where harm has occured

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3
Q

When can a hazard be defined a disaster?

A
  • 10 or more deaths have occured or when there is a declaration of an emergency by the relative government
  • Insurance companies define it when economic losses exceed 1.5million
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4
Q

What can hazards be caused by?

A
  • Human actions (explosions, chemical releases into atmosphere and nucler incidents)
  • Natural (earthquakes, storms, volcanoes and wildfires)
  • Natural events are often caused by human action e.g wildfires due to human carelessness
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5
Q

What factord affect the impacts of hazards?

A

-The location of rge hazard relative to areas of population and the magnitude and extent of the hazard
- Specifc to the type of hazard e.g. type and exposivity of a volcanoe, Nature and continental shelf and shoreline for tsunamis

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6
Q

What are geophysical hazard?

A

Geophysical= caused by the movement of tectonic plates, driven by the earths own internal energy

E.g. Plate tectonics, volcanoes, sesimic activity

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7
Q

What are atmospheric hazards?

A

Atmospheric = Caused by processes occurring in our atmosphere

E.g. Tropical storms, Droughts

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8
Q

What are hydrological hazards?

A

Hydrological = driven by water bodies, mainly the ocean

E.g. Floods, Storm surges, Tsunamis

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9
Q

What are primary impacts?

A

Primary impacts = Those that have an immediate effect on the affected area, such as destruction of infrastructure and contamination of water supplies

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10
Q

What are secondary impacts?

A

Secondary impacts = impacts that have occurred after the disaster has occurred such as disease, economic recession and contamination of water supplies

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11
Q

What is hazard perception?

A

Hazard perception = the way in which someone understands or interprets a hazard

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12
Q

What is hazard perception determined by?

A
  • The effect that the hazard may have on our lives and this increases if people have a direct experience with a hazard and the long term impacts it caused
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13
Q

What are the negatives of urbanisation for hazards?

A
  • The pressure of an increasing population and subsequent demand for land has resulted in building on areas that are at increased risk

Population expansion can increase the risk of a hazard

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14
Q

How are hazards percieved as advantageous to some people?

A
  • some people make use of the fertile soils on floodplains or in the vicinity of a volcanoe can be considered a risk worth taking and living with the threat is accepted
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15
Q

What are the effects of diasters on HDES ?

A

HDES effects tend to do little long term damage to the economy as there is enough wealth and potential for redevelopment to br able to rebuild infrastructure and supporting those directly affected

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16
Q

What are the effects of disasters on LDES?

A

LDES are more reliant on support and aid both in the immediate aftermath of an event and also in the long term

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17
Q

What are the local level responses to a disaster?

A

Saving possessions, and safeguarding property

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18
Q

What are the global responses to a disaster?

A

Co-ordination rescue and humanitarian aid

The intensity and magnitude if the event as well as the original state of the infrastructure affects the spread of international response

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19
Q

What is the automatic disaster analysis and mapping system (ADAM)?

A

A database that pools informarion from the US geographical society, world bank and world food programme

It allows almost immediate access to such information as the scale of the disaster and what supplies are avaliablly localy

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20
Q

What is fatalism?

A

Fatalism = acceptance - a view that nothing can be done to mitigate the hazard and therefore the outcome and the loss will be inevitable

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21
Q

What is community prepareness/risk sharing?

A

Prearranged measures aimed at reducing the loss of life and property damage
Can be done throigh public education and awareness programmes, evacuation procedures and provison of the neccesary resucres before hazards occur

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22
Q

Prediction

A

The ability to give warnings so that action can be taken to reduce the impact of hazardous events

E.g. remote sensing and seismic monitoring, advances in communications and warnings communication promptly

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23
Q

Preparation

A

Prearranfed measures that aim to reduce teh loss of life and damage to property throuhh increased awareness

E.g. Buildings/infrasturtucre made to withstand gazards

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24
Q

Mitigation

A

Physical action that takes place to lessen the impact of a natural hazard

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25
Q

Prevention

A

Trying to stop the natural hazard occurring at all (impossible)

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26
Q

Adaptation

A

Changing behaviour or physical/natural environment to reduce the risk

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27
Q
A
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28
Q

What is hazard management cycle ?

A

Hazard management cycle = shows phases of response, recovery, mitigation and prepardness in the management of a hazard

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29
Q

Recovery

A
  • In short term how can affected area regain its essential services to aid long term recovery
  • In the long term how will impacted area return to normal
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30
Q

Response

A
  • Speed will depend on the effectiveness of emergency resposne teams and level of prepardness
  • Short term responses focus on saving lives
  • Assesment of damage will determine level of recovery required
31
Q

prevention & mitigation

A
  • How can impact of an event be lessend e.g. retrofitting or firebreaks in area ro prove to wildfires
  • Will they be short term / long term? Will they be hard or soft engineered?
  • How much aid assistance comes from overseas
  • Will communuties be insured even in HICS?
32
Q

preparation

A
  • Is the community ready for the next hazard ( education)
  • Good preparation allows for a more effective response to another event
  • High risk areas tend to be better prepared
33
Q

What is parks repsonse model ?

A

Parks response model = shows the changing quality of life through different phases of a disaster

34
Q

What is a multi hazard zone?

A

Multi hazard zone = an area which is prone to a range of hazards. Some of these may be interrelated such as earthquakes triggering a landslide

35
Q

What is Deggs model?

A

Deggs model shows the relationship between vulnerability, hazards and disaster. He indicates the interconnectedness between physical and human factors of place (synopicity and varying rates of different players / stakeholders

36
Q

What are root causes?

A

Root causes = human context of place. This affects the vulnerability of the population

37
Q

Resillence

A

Resilience = the ability of a system, community or society exposed to hazards to resist, absorb and accommodate to and recover from the effect of a hazard

38
Q

Risk sharing

A

Risk sharing = working together to reduce the risk and sharing the cost of hazard response

39
Q

Primary hazard

A

Primary hazard = happen immediatley and are caused by the energy released by the earth

40
Q

Secondary hazard

A

Secondary hazards = happen as a result of the primary hazards

41
Q

What is sea floor spreading?

A

Sea-floor spreading = Movement of oceanic crustal plates away from constructive plate margins

42
Q

Who produced the idea of sea floor spreading and when?

A

-Harry Hess in 1962 and this helped support wegeners theory of continental drift
-Hess discovered that rocks increased in age with distance from mid ocean ridges and that new oceanic crust were therefore being formed when plates diverged
- Hess theory was backed by the magnetic dating of these rocks (paleomagnetism)
-

43
Q

Facts about sea floor spreading?

A
  • 12,000ft long mountain range formed as mid alantic ridge a ridge of underwater volcanoes
    -Molten rock pushed up from inside earth at the ridge new crust new ocean floor
  • Rate of spreading is expected to be up to 5cm per year
44
Q

What is paleomagnetism?

A

Paleomagnetism = Measurement of the magnetism preserved in older rocks

45
Q

Facts about paleomagnetism?

A

-Approximatley every 400,000 years the earths magnetic field swtitch polarity between north and south
-Studies in 1960s of magnite ( iron oxide) produced from the balsatic lava along mid ocean ridge records the earths magentic orientation at that time
-Both age and magnetic orientation and symetrical suggesting that the oceanic crust is slowly spreading away from this boundary and therefore supporrs theory of contineyal drift
-

46
Q

What is mantle convention?

A

Mantle convention = the rising and falling of magma within the asthenosphere

47
Q

Facts about the asthenosphere

A
48
Q

Gravitational sliding

A

Gravitational sliding = the movement of tectonic plates as a result of gravity at mid-ocean ridges and deep sea trenches (ridge push and slab pull)

49
Q

Ridge push

A

Ridge push = the higher elevation at an ocean ridge causes gravity to push down and drag crust away from the ridge

50
Q

Slab pull

A

Slab pull = The process whereby , following subduction, the lithosphere sinks into the mantle under its own weight ‘pulling’ the rest of the plate with it

51
Q

How does ridge push occur?

A

Ridge push is a result of gravitational forces acting on young oceanic lithosphere, causing it to slide down the asthenosphere and push on the lithospheric material further away from the ridges

52
Q

How does slab pull occur?

A

Slab pull is a force that results from denser oceanic plates subducting beneath less dense continental plates. The gravitational force of the sinking oceanic plate drags the rest of the plate along with the portion experiencing slab pull

53
Q
A
54
Q

What are plate margins?

A

Plate margins = the place where two plates meet and the crust either side of this is the junction

55
Q

What are constructive (divergent) plate margins?

A

Constructive plate margins = when two plates separate (diverge) and form a constructive margin

56
Q

What are the two types of divergence?

A

mid - ocean ridges , rift valleys

57
Q

How do mid ocean ridges form?

A
  • Forms thousands of kilometres across the floor of submarine mountains
  • Transform faults cut across the ridges, occurring at a right angle to the plate boundary, separating sections of the ridge
  • Can rise up to 4000m above ocean floor
    -Volcanic eruptions along ridges build
58
Q

How are rift valleys formed?

A
  • Formed when the lithosphere stretches causing it to fracture into sets of parallel faults
  • The land between these faults then collapse into deep wide valleys that are separated by upright blocks of land called horsts
59
Q

What are destructive (convergent) plate margins?

A

Destructive plate margins = when two plates collide they form a destructive plate margin

60
Q

What are the three types of destructive plate margins?

A
  • Oceanic meets continental
    -Oceanic meets oceanic
    -Continental meets continental
61
Q

Oceanic meets contitnental?

A
  • The meeting of two plates is associated with subduction
  • Oceanic plate is denser than lighter contitnental plate so it subducts beneath it
  • Exact point of collision is marked by bending of the oceanic plate to form a deep ocean trench (e.g. peru -chile trench)
  • As two plates converge the contitnental land mass was uplifted, compressed, bucked and folded into **chains of fold mountains **
  • Continuous compressing, simple folding can become assymetrical then overfolded making a **recumbent fold **
  • Nappe can occur if increased compressing makes middle section thin
  • Descending oceanic plate melts at depth beyond 100km and completley destroyed by 700km
  • Friction may lead to stresses building up which may be released as **intermediate or deep focus earthquakes **
  • Melted oceanic creates magma which rises in great plumes passing through cracks and faults
62
Q

What is the zone of melting?

A

Benioff zone - caused by both increasing depth and friction

63
Q

Oceanic plate meeting oceanic plate

A
  • One plate (faster or denser) subducts beneath the other
  • Leads to formation of a deep ocean trench and melting
  • Rising magma from benioff zone forms crescents of submarine volcanoes along plate margins which may grow to form **island arcs **
64
Q
A
64
Q
A
65
Q

Continental meets continetal

A
  • Continental are of lower density than the athenosphere beneath them which results in no subduction occuring
  • Colliding plates become uplifted and buckle to form** high fold mountains **
  • No volcanic activity as there is no subduction but **shallow focus earthquakes **can be triggered
  • Young fold mountains continually growing and compressing
66
Q
A
67
Q

What are conservative plate margins?

A

Conservative plate margins = where two plates slide past eachother causing earthquakes to occur

68
Q

Two plates sliding **past **eachother

Conservative plate margin

A
  • Crust is not destroyed or subducted
  • No melting rock which results in no volcanic activity or formation of new crust
  • Very active margins and associated with powerful earthquakes
  • Friction between two moving plates leads to stresses building up wherever sticking occurs
  • Stresses may be released as shallow focus earthquakes such as LA (1994), SF (1906, 1989)
69
Q

Magma plumes

A
  • Hotspots form around core if decay is concentrated
  • Heat in lower mantle creates localised thermal currents where magma plumes rise vertically
    Usually located at plate margins but can be risen within centre of plates and burn through lithosphere to create volcanic activity on the surface
  • Hotspots remain stationary, movement of overlaying plate results in formation of chain of active and extinct volcanoes as plate moves away
70
Q

What is a hotspot?

A
71
Q

What are transform faults?

A
72
Q

The great african rift valley

A

An example of divergent plate boundary that occur in the middle of continents
May eventually form a new ocean as eastern africa splits away from the rest of the continent

73
Q
A

Geography (5 decks)

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