Key Terms Flashcards

1
Q

Define adaptation.

A

The attempts by people / communities to live with hazard events.

By adjusting their living conditions, people are able to reduce their levels of vulnerability.

(Eg avoiding building on sites that are vulnerable to storm surges but stay within that same area).

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2
Q

Define fatalism.

A

A view of a hazard event that suggests that people can’t influence or shape the outcome, therefore nothing can be done to mitigate against it. Can be seen as “God’s will”.

People with such an attitude put in place no preventative measures.

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3
Q

Define natural hazards.

A

Events which are perceived to be a threat to people and the built and natural environment.

They occur in the physical environments of the atmosphere, lithosphere and hydrosphere.

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4
Q

Define perception.

A

The way in which an individual or group views the threat of a hazard event. This will ultimately determine the course of action taken by individuals / response they expect from the government.

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5
Q

Define frequency.

A

The distribution of a hazard through time.

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6
Q

Define magnitude.

A

The assessment of the size of the impact of a hazard event.

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7
Q

Define fear in the context of hazards.

A

The perception of the hazard is such that people feel so vulnerable to an event that they are no longer able to face living in an area and move away to regions perceived to be unaffected by the hazard.

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8
Q

Define community preparedness

A

Prearranged measures that aim to reduce the loss of life and property damage through public education and awareness programmes, evacuation procedures, the provision of medical, food and shelter supplies and the taking out of insurance.

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9
Q

Define integrated risk management.

A

The process of considering the social economic and political factors involved in risk analysis; determining the acceptability of damage / disruption and deciding the actions to be taken to minimise damage / disruption.

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10
Q

Define prediction.

A

The ability to give warnings so they action can be taken to reduce the impact of hazard events.

Improved monitoring, information and communications tech have meant that predicting hazards and issuing warnings have become more important in recent years.

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11
Q

Define primary effects.

A

The effects of a hazard that result directly from that event.

Eg lava, pyroclastic flow. Or ground shaking in earthquakes.

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12
Q

Define secondary effects.

A

The events that result from the primary impact of the hazard event.

Eg in volcanoes - flooding (from melting ice chaos and glaciers) and lahars. Eg in earthquakes - tsunamis and fires (from ruptured gas pipes).

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13
Q

Define resilience.

A

The sustained ability of individuals or communities to be able to utilise available resources to respond to, withstand, and recover from the effects of natural hazard events.

Communities that are resilient are able to miniseries the effects of the event, enabling them to return to normal life ASAP.

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14
Q

Define lahars.

A

These are formed form volcanic ash mixing with water and flowing downhill. Essentially they’re volcanic mudflows.

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15
Q

Define lava.

A

Molten rock (magma) flowing onto the surface.

  • acid lava solidifies quickly but basic (basaltic) lava tends to flow some distance before solidifying.
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16
Q

Define lithosphere.

A

The layer of the Earth which consists of the crust and upper section of the mantle.
It’s this later which is split into a number of tectonic plates.

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17
Q

Define pyroclastic flows.

A

Formed when hot gas (over 800*C) and tephra.

After ejection form the volcano they can flow down the sides of a mountain at speeds over 700km.

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18
Q

Define tephra.

A

The solid matter ejected from a volcano into the air.

It ranges form volcanic bombs (large) to ash (fine).

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19
Q

Define earthquake.

A

As the crust of the Earth is constantly moving, there tends to be a slow build up of stress within the rocks. When this pressure is released, parts of the surface experience an intense shaking motion for a short period.

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20
Q

Define retrofitting.

A

In earthquake-prone areas, buildings and other structures can be fitted with devices eg shock absorbers and cross bracing to make them more earthquake proof.

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21
Q

Define tsunami.

A

Giant sea waves generated by shallow focus underwater earthquakes, violent volcanic eruptions, underwater debris slides and landslides into the sea.

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22
Q

Define mitigation.

A

Strategies designed to reduce / eliminate risks to people and property from natural hazards. Money spent prior to a hazardous event to reduce the impact can result in substantial savings in life and property following the event.

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23
Q

Define storm surge.

A

A rapid rise in sea level in which water is piled up against a coastline to a level far in excess of the normal conditions at high tide.

Usually produced during the passage of a tropical storm when wind driven waves pile up against a coastline combined with the ocean heaving upwards as a result of much lower air pressure.

24
Q

Define retardants.

A

Chemicals sprayed onto fires in order to slow them down. They’re composed of nitrates, ammonia, phosphates, sulphate sand thickening agents.

25
Q

Define pyrophytic vegetation.

A

Pyrophytes are plants that are adapted to tolerate fire.

Methods of survival include thick lark, tissue with a high moisture content and underground storage structures.

26
Q

Define protection

A

To protect people, their possessions and the built environment from the impact of an event.

Usually involves modifications to the built environment e.g. improved sea walls and earthquake proof buildings.

27
Q

Define the disaster/response curve.

A

To show that hazard events can have varying impacts over time, Park created an impact/response model showing an early stage (before the disaster), when the event happens, next is relief, then rehabilitation, then reconstruction.

28
Q

In the disaster/response curve what is ‘relief’?

A

Where medical attention, rescue services and overall care are delivered. Can last a few hours to several days.

29
Q

In the disaster/response curve, what is ‘rehabilitation’?

A

Where people try to return the state of things to normal by providing food, water and shelter to those most affected.

30
Q

In the disaster/response curve, what is ‘reconstruction’?

A

Where the infrastructure are reconstructed and crops are regrown. Can take weeks to several years.

31
Q

Define distribution.

A

The spatial coverage of the hazard.

This can refer to the area affected by a single event, some of which can have a very localised effect, whilst others have a much wider effect eg tsunamis which can cross large oceans.

32
Q

What is the core?

A

Made up of dense ricks containing iron and nickel alloys.

Is divided into a solid inner core and molten outer one (temp of over 5000*C).

33
Q

Define primordial heat.

A

Heat left over from the Earth’s formation which contributes to the high temperature of the Earth’s outer core.

34
Q

Define radiogenic heat.

A

Heat produced by the radioactive decay of isotopes, particularly Potassium-40.

35
Q

Define the mantle.

A

Made up of molten and semi-molten rocks containing lighter elements eg silicon and oxygen.

36
Q

Define the crust.

A

Even lighter than the mantle, because of the elements present, the most abundant being silicon, oxygen and potassium.

Varies in thickness - beneath the ocean it’s 10km, but below continents it’s 40km.

37
Q

What does the lithosphere consist of?

A

The crust and rigid upper section of the mantle. Approx 90km thick.

38
Q

What does the aesthenosphere consist of?

A

The aesthenosphere lies beneath the lithosphere and is semi-molten in which the plates float and move.

39
Q

Define subduction.

A

Large areas of ocean floor are pulled downward, forming oceanic trenches.

40
Q

What is an ocean ridge?

A

Where plates have moved apart in oceanic areas, and the space between them is filled with basaltic labs upwelling from below to form a ridge.

41
Q

What is a ridge valley?

A

Plates move apart on continental areas. Areas of crust drop down between parallel faults to form the valley.

42
Q

What is a Horst?

A

The area between two parallel rift valleys, forming an upstanding block

43
Q

What are deep sea trenches?

A

Where oceanic and continental plates meet, the denser oceanic plate is forced underneath the lighter continental one (subduction).

The downwarping of the oceanic plate forms a very deep part of the ocean - a trench.

44
Q

What are island arcs?

A

During subduction, the descending plate encounters hotter surroundings, and this coupled with the heat generated from friction, begins to melt the plate.

As this material is less dense than the surrounding atmosphere, it begins to rise towards the surface as plutons of magma. Eventually these reach the surface and form complex, composition and explosive volcanoes.

45
Q

What are young fold mountains

A

Because the plates forming the continental crust have a much lower density than the underlying layers, there’s little subduction. Instead, as plates move together, their edges and the sediments between them are forced up into fold mountains.

(As there’s little subduction, there’s no volcanic activity).

46
Q

What is ridge push?

A

At constructive boundaries, oceanic plates experience a force that acts away from the ocean ridge, as a result of gravity acting down the slope of the ridge.

47
Q

What is slab pull?

A

A downward gravitational force acts on the cold and dense descending plate as it sinks into the mantle. This plus the whole oceanic plate down as a result of the negative buoyancy of the plate.

48
Q

What is a hotspot?

A

In certain places, a concentration of radioactive elements below the crust causes a hotspot to develop. From this, a plume of magma rises to eat into the plate above. When this lava breaks through to the surface, active volcanoes form above the spot.

49
Q

What is the volcanic explosivity index (VEI)?

A

A logarithmic scale running from 0-8

50
Q

What is acid rain as a result of volcanoes?

A

Volcanoes emit gases including sulphur. When this combined with atmospheric moisture, acid rain results.

51
Q

What is the ‘focus’?

A

The point at which pressure release occurs within the crust.

52
Q

What is the epicentre?

A

The point immediately above the focus, on the Earth’s surface.

53
Q

What is the Richter scale?

A

A logarithmic scale on a scale 1-10.

(An event measured at 7 has an amplitude 10x greater than 6).

54
Q

What is the moment release scale (MMS)?

A

Identifies energy release from earthquakes. Used instead of the Richter scale.

55
Q

What is the Mercalli scale?

A

Measures the intensity of an earthquake on a 12 point scale from I to XIII.

56
Q

What is soil liquefaction?

A

When violently shaken, sound with a high water content lose their mechanical strength and start to behave like a fluid.