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A level GEOGRAPHGY edexcel > Tectonic hazards > Flashcards

Tectonic hazards Flashcards

1
Q

what is accretion wedge

A

-the accumulation of material at the point of subduction

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2
Q

what is aseismic building

A

buildings designed to withstand or minimise destruction during an earthquake

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3
Q

what is the asthenosphere

A

the upper mantle layer of the earth . its semi molten and approximately 200km wide

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4
Q

what is ash

A

fine particles and dust ejected during an eruption , which can remain airborne as clouds or accumulate on the ground

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5
Q

what is the continental crust

A

crust that forms the continents of the lithosphere , on average 35km thick

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6
Q

what is continental drift

A

the movement of tectonic plates , due to varying weights of crust . it was originally though convection currents moved plates but now slab pull is though of as the primary driving force.

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7
Q

what is Degg’s model

A

model shows that a hazard becomes a disaster if it affects a vulnerable population.

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8
Q

what is the epicentre

A

the point on the surface , directly above the earth quakes origin

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9
Q

what is the focus

A

the place in the crust where the pressure / seismic energy is released

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10
Q

what is the hazard mitigation cycle

A

the sequence of governance of a natural hazard: monitoring and prediction, mitigation, preparedness.

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11
Q

what is a hot spot

A

volcanoes found away from the plate boundary , due to magma plume closer to the surface.

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12
Q

what is Jokulhaup

A

a sudden glacial flood caused by a glacier on top of or near a volcano melting due to heat from the eruption

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13
Q

what is a lahar

A

a flow of mud and debris

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14
Q

what is the lithosphere

A

the upper crust of the earth.

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15
Q

what is a love wave

A

a surface earthquake wave with horizontal displacement

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16
Q

what is a mid ocean ridge

A

Partin oceanic plates at a constructive plate boundary creates a ridge , with new land at the base of the oceanic valley

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17
Q

what is the oceanic crust

A

crust, usually thinner than continental crust , that forms the sea floor . it is on average 7km thick

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18
Q

what is paleomagnetism

A

the alternating polarisation of new land created.
as magma cools, the magnetic elements within will align with the earths magnetic field , which can alternate over thousands of years.

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19
Q

what is the park model

A

a model describing the decline and recovery of a country over time, following a natural disaster

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20
Q

what are primary waves

A

an earthquake wave causing compressions within the body of the rock

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21
Q

what is pyroclastic flow

A

a mixture of gases and rock fragments , at high temperatures travelling at rapid speeds.

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22
Q

what is a Rayleigh wave

A

a surface earthquake wave causing both horizontal vertical displacement

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23
Q

what is a Richter scale

A

a logarithmic measure of earthquakes intensity.

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24
Q

what is a secondary wave

A

an earthquake wave causing vertical displacement within the body of rock

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25
Q

what is a seismic wave

A

the energy relesed during an earthquake in the forms of primary , secondary , love and Rayleigh waves

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26
Q

what is slab pull

A

the force contributing to the movement of tectonic plates . slab pull is due to the weight of the plate.

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27
Q

what is subduction

A

oceanic plate is forced below continental plate , due to the oceanic plate being more dense than the continental plate.

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28
Q

what is a tsunami

A

initial vertical water displacement creates waves, with large destructive power.

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29
Q

what is the volcanic explosivity index

A

a measure of magnitude of a volcanos eruption

30
Q

what is the wadati-benioff zone

A

a region of the subducting plate , most affected by pressure and friction, where most destructive margin earthquakes originate

31
Q

what is a destructive plate boundary

A

Continental and oceanic:
● Denser oceanic plate subducts below
the continental.
● The plate subducting leaves a deep
ocean trench.
● Built up pressure from the melting
plate cause explosive volcanoes
bursting through the continental plate

32
Q

what is a constructive boundary

A

Oceanic and oceanic:
● Magma rises in between the gap left by
the two plates separating, forming
new land when it cools.
● Less explosive underwater volcanoes
formed as magma rises.
● New land forming on the ocean floor by
lava filling the gaps is known as sea
floor spreading (as the floor spreads
and gets wider).
Continental to continental:
● Any land in the middle of the separation
is forced apart, causing a rift valley.
● Volcanoes form where the magma
rises.
● Eventually the gap will most likely fill
with water and separate completely
from the main island.

33
Q

what is ridge push

A

The slope created when plates move apart has
gravity acting upon it as it is at a higher
elevation. Gravity pushes the plates further
away, widening the gap (as this movement is
influenced by gravity, it is known as
gravitational sliding).

34
Q

what plate boundary does earthquakes occur at

A

The most powerful earthquakes occur at destructive and conservative
boundaries

35
Q

what plate boundary does Tsunami occur at

A

occur at destructive
boundaries

36
Q

what plate boundary does Volcanic hazards occur at

A

The world’s active volcanoes are found at constructive and destructive plate
boundaries, and at hotspots

37
Q

what is the equation for risk

A

Risk = hazard x vulnerability / capacity to cope

38
Q

what is the PAR model

A

Root causes - dynamic pressures - unsafe conditions- disaster( risk - hazard x vulnerability) - natural hazard

39
Q

what are the steps to the park’s model

A

step 1 - Relief ( hours-day)
Immediate local response ,foreign aid
step 2- Rehabilitation ( days or weeks )
Services ,Temporary shelters ,hospitals set up Food and water
step 3-Reconstruction ( weeks - years)
Restoring , Infrastructure , future event

40
Q

What did believe Alfred Wegener 1912

A

All continents were once joined in a super continent called Pangea. Continental drift caused Pangea to move apart.

41
Q

What did say Holmes 1929

A

Convection in the mantle is the force behind continental drift.

42
Q

What is a Volcanic Hotspot

A

An area in the mantle from which heat rises as a hot thermal plume from deep in the earth.

43
Q

What is the lithosphere?

A

the rigid outer part of the earth, consisting of the crust and upper mantle.

44
Q

What is the asthenosphere?

A

the upper layer of the earth’s mantle, below the lithosphere.

45
Q

Factors affecting earthquake intensity

A

*Duration of locked fault
*Depth of hypo-centre
*Timing & intensity of seismic waves

46
Q

What Is basaltic magma

A

magma that has low viscosity and low silica and gas content; eruption is non-explosive

47
Q

Rhyolitic Magma

A

magma that has a high viscosity and high silica and gas content; eruption tends to be very explosive

48
Q

Explain a Composite volcanoes

A

large, steep-sided volcanoes that result from explosive eruptions of andesitic and rhyolitic lava and ash along convergent plate boundaries. Poses most danger to Hunan life.

49
Q

Explain a Shield Volcanoes

A

Gently sloping mountains formed by thin, runny lava. Frequently eruptive.

50
Q

What is the “Benoiff zone”

A

A dipping flat zone where earthquakes are produced by the interaction of a submerging oceanic crustal plate with a continental plate.

51
Q

What is a fault

A

A fracture in the rocks that make up the earth’s crust

52
Q

What is an epicentre?

A

The point on the Earth’s surface straight above the focus.

53
Q

What are Secondary Hazards of Earthquakes

A

*liquefaction
*landslides
*tsunamis

54
Q

What is soil liquefaction?

A

When an earthquake causes the ground to shake to the point of making it liquid.

55
Q

What is a landslide?

A

the sliding down of a mass of earth or rock from a mountain or cliff.

56
Q

What is a tsunami?

A

Convection currents in the mantle move plates towards each-other. Pressure builds up as the denser plate is forced beneath the overriding plate. An EQ occurs. Water is displaced creating a wave which spreads out. As wave approaches shore, height increases and wave length shortens

57
Q

What are the Primary Hazards of a Volcano?

A

*pyroclastic flow
*tephra
*volcanic gases
*lava flows

58
Q

What is tephra?

A

rock fragments and particles ejected by a volcanic eruption

59
Q

What are volcanic gases?

A

Water, sulphur dioxide, hydrogen and CO2.

60
Q

What are the secondary impacts of a volcano?

A

*Jokulhlaups
*Lahars

61
Q

What are Jokulhlaups?

A

Sudden, violent and short-lived increase in discharge of glacial meltwater

62
Q

What is community resilience?

A

The ability to cope with a hazard using your own resources.

63
Q

Reasons Cumulative Act Effect Model

A

Acknowledges that pre-existing vulnerabilities in society can exacerbate the impacts of a hazard and make it into a disaster

64
Q

Governance

A

The sum of the many ways individuals and institutions, public and private, manage their common affairs

65
Q

what are the three ways of managing a tectonic hazard.

A

Modify the Event,
Modify the Vulnerability, Modify the Loss​.

66
Q

Explain Modifying the event .

A

we can’t control seismic activity. how can control the design of buildings through civil engineering using micro and macro methods.
Micro - strengthening individual buildings and structures.
Macro- large scale support and protective measures designed to protect whole communities.

67
Q

what are the different types of modifications in modifying the event.

A
  • Land use zoning
  • Resistant buildings
  • Tsunami defences
  • Lava diversion
68
Q

what are the advantages and disadvantages of Land use zoning

A

+ low cost
+reduced vulnerability
-stops economic
- development on some high value land
- strict enforcement requirement .

69
Q

what are the advantages and disadvantages of Resistant buildings

A

+ can help prevent collapsing
+protects people and property.
- high cost for larger buildings
- Low income families cannot afford this.

70
Q

what are the advantages and disadvantages of Tsunami defences

A

+Reduces damages
+ Provides security
- Very high cost
-Doesn’t look nice
- Can be overtopped

71
Q

what are the advantages and disadvantages of Lava diversion

A

+ Diverts lava away
+ low cost
-only works for low VEI lava

72
Q

what are the different modifications for modify vulnerability.

A

Hi tech scientific monitoring
Community preparedness and education .
Adaptation

A level GEOGRAPHGY edexcel (4 decks)

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