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Edexcel A Level Geography > Tectonics > Flashcards

Tectonics Flashcards

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1
Q

Hazard Risk Equation

A

Risk = (Event x vulnerability) / Capacity to cope
Determine magnitude - Richter scales, P&S waves or moment magnitude
Determine intensity - Mercalli (amount of damage), which could be affected by local conditions
Look at the power/energy of the event, how much risk different people are at, and how well the event can be dealt with

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2
Q

What’s the effect of the earthquake on Japan?

A
  • High damage made Japan economically vulnerable, and they were cut off from the global economy
  • Globalisation affected the impact on Tohoku, and countries who import Japanese goods
  • Poorer, low income people live in the high risk areas e.g. marshy land, hills, near rivers or volcanoes
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3
Q

What is the Pressure and Release Model? The relationship between hazard + wider context?

A
  • Shows what we should tackle to reduce risk of disaster
  • A good capacity to cope can still mean that a large disaster has a sudden, negative effect
  • Wider context can change what’s happening in a certain area e.g. tectonic plates in Tohoku
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4
Q

What are the factors of the PAR model?

A
  • Unsafe conditions: landslides block roads, concrete infrastructure, building structure and codes (physical env), specific groups at risk
  • Dynamic pressures: population growth, deforestation and agricultural dependency, rapid urbanisation
  • Root causes: less funding in rural areas (economic system), tension between governments means less aid (political system), no focus on aseismic construction
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5
Q

Park’s model

A
  • Helps plan what to do and track what stage you’re at
    1. Pre-disaster - modify cause and event
    2. Hazardous event
    3. Search, rescue and care
    4. Rehabilitation, modify loss and national/international help
    5. Reduce vulnerability and restore normality (rebuild infrastructure)
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6
Q

Park’s response curve for diff hazard events and diff stages of development

A
  • Varies depending on size/timing of hazard event and the country it hits
  • Need resilience and efficiency
  • Kashmir: emerging country but developing area, Stage 3
  • Christchurch: developed, Stage 5 (not prone to hazards, so limited prep)
  • Tohoku: developed, Stage 1 (well prepared, but better architecture/tech)
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7
Q

Earth’s internal structure

A
  • Crust, mantle, outer core (liquid metal swirls + movement creates earth’s magnetic field), inner core
  • As you go deeper, pressure and temperature increase melting point (harder to melt)
  • 90% of heat at depth from radioactive decay in mantle
  • Some latent heat from core
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8
Q

Mantle convection

A
  • Magma creates convection currents
  • Closest to melting point at asthenosphere
  • Partially melts due to decompression, closer to melting point as pressure decreases, forms magma chambers under divergent boundaries
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9
Q

Seafloor spreading

A
  • New oceanic crust is formed through volcanic activity, then slowly moving away from the ridge
  • Ridge push causes seafloor spreading
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10
Q

Ridge push and slab pull

A

Mid-ocean ridge slides away under gravity and forced apart in opposite directions
Slab pull - force behind tectonic plates, subduction zones pull the plate down

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11
Q

Lava flows and pyroclastic flows

A
  • Molten magma viscosity depends on amount of SiO2, buildings can be burnt or covered
  • Bubbles of magma in vent burst + eject hot gases/pyroclastic material (glass, pumice, crystals, ash), deposits cause secondary hazards
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12
Q

Ash falls and gas eruptions

A
  • Carried into atmosphere, falls locally causing roof collapse, difficulty breathing, bury crops/vegetation and can disrupt flight paths (engine blade abrasion)
  • H2O vapour means heavy rainfall, SO2 particles in stratosphere cause acid rain, fluorine concentration increases so contaminates farmland/water supply
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13
Q

Lahars

A
  • Water with volcanic deposits flows along valleys
  • Heavy rain or ash in humid air, then condensation
  • Fast and carry lots of material (60km/hr and 50m deep)
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14
Q

Tectonic mega-disaster regional significance (Iceland)

A
  • Ash cloud reached N Italy meant flight disruptions in Europe but reduced air/noise pollution
  • Had to travel on land so more traffic + higher train prices
  • Europe econ lost $5 million
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15
Q

What is the global significance of Iceland’s tectonic disaster?

A
  • Affected as far as Japan and industries in Asia

- Kenyan flower industry lost $2 million of produce

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16
Q

Tectonic disaster economic and human impacts

A
  • African economy lost $65 mil
  • Airlines lost $1.1 billion
  • Knock on effect from cancelled events
  • Ash affected health in S Iceland
  • Postponed political events
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17
Q

Strategies to modify event

A
  • Need to monitor gas emissions, clouds and faultline strain

- Tilt-ometers measure ground deformation

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18
Q

What does land use zoning and hazard resistant design involve?

A
  • Keep residential/commercial areas away from all volcanoes, but hard due to fertile soil
  • Retrofit buildings and cross-bracing, but expensive and needs govmt legislation
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19
Q

Engineering defences and diversion of lava flows

A
  • Sea walls/mangroves absorb tsunami wave energy, backup utility for hospitals/police stations, drain craters to prevent lahars
  • Spray seawater to solidify lava and make basaltic rock
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20
Q

How tsunamis are caused at subduction zones due to seabed displacement (and slab pull)

A
  • Oceanic crust goes beneath continental
  • Reduced melting temperature in asthenosphere from seawater
  • Pull is force behind plates, causing EQ
  • Seabed thrusts up from sub-marine EQ, then tsunami occurs
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21
Q

How are tsunami waves formed?

A
  • Water column creates tsunami waves, which radiate out at 800km/hr
  • Get closer to coast, slow down from seabed friction to 40km/hr
  • Wavelengths shorten, waves catch up, amplitude increases and wave breaks
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22
Q

Variables affecting tsunamis

A
  • Distance from source (lose energy over distance)
  • Offshore bathymetry (shallow/deep)
  • Coastline orientation
  • Shape of coastline (estuaries funnel and cause larger amplitudes)
  • Coastal topography (height) and geology
  • Extent of vertical fault displacement (therefore amt. of water displaced)
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23
Q

Benioff Zone

A
  • Planar zone that corresponds with slab going down
  • Speed/movement of rock produces EQs
  • Locked faults create more frictional resistance (greater stress)
24
Q

Focal depth

A
  • Can be deep or shallow

- If deep, EQ may lose energy as it reaches the surface

25
Q

What factors of EQs and slopes increase stress? (landslides)

A
  • Change focal depth (higher moment magnitude)
  • Change moment magnitude
  • Higher slope (more avalanches/freeze thaw)
  • Higher mountain uplift (more precipitation)
26
Q

How EQs, volcanoes and slopes decrease strength (landslides)

A
  • Amount of folding (steeper slope)
  • Lava type (doesn’t flow far, making land steeper)
  • More hydration melting (explosive and andesitic lava)
  • EQ destroys vegetation
27
Q

What is a multiple-hazard zone?

A
  • Two or more natural hazards

- Sometimes simultaneously, producing a complex disaster

28
Q

What do hydrometeorological hazards involve in the Philippines?

A
  • Tropical monsoon climate in SE Asia’s typhoon belt
  • Increased risk of storm surges, floods and landslides
  • El Niño periodic droughts causes wildfires
29
Q

What is the hydrometeorological contribution to tectonic disaster?

A
  • Plate boundaries in Ring of Fire, coasts face Pacific Ocean so are tsunami prone
  • Events leave steep rugged slopes and poor vegetation
30
Q

Hazard management cycle

A
  1. Response - emergency services
  2. Recovery - fixing everything e.g. lava removal, sorting out housing
  3. Mitigation- reduce vulnerability (of people)
  4. Preparedness - capacity to cope, putting plans/infrastructure in place
31
Q

What makes capacity to cope difficult (Catania)

A
  • Each eruption is difficult - fractures in different places, lava viscosity and gas eruptions vary
  • Unexpected timings of minor eruptions
  • Computer modelling data may not always be accurate
  • Crucial infrastructure is vulnerable - single road access to ski resorts, towns, and limited airport alternatives
  • High financial cost in poor part of Italy
32
Q

P Waves

A
  • Short wavelength
  • Travel fast through solid and liquid
  • Push and pull in direction of travel
  • Trigger warning systems and aid immediate response
33
Q

S Waves

A
  • Slower and longer wavelength
  • Only move through solid rock
  • At a right angle to the direction of travel
34
Q

L Waves

A
  • Slowest but most destructive
  • Only move at surface
  • Largest amplitude and shakes from side to side
35
Q

How are crustal fracturing and ground shaking caused by EQ waves?

A
  • The energy released cracks crust and vertically displaces land
  • Shaking causes infrastructure collapse
36
Q

Secondary hazards from EQ waves

A
  • Liquefaction: shaking destabilises the soil, increasing space between grains, so soil flows like liquid
  • Landslides: increased stress on rock slopes
37
Q

Inequality of access to education influences vulnerability (Nepal)

A
  • Difficult to access damaged school in a mountainous environment
  • High illiteracy rates with 70% of men, 40% of women
38
Q

How does access to housing influence vulnerability? (Nepal)

A
  • Nepalese share inherited property, so tall thin houses are vertically split
  • 5 mil crammed in shoddy, concrete buildings, narrow alleys and hillsides in Kathmandu
39
Q

How does access to healthcare influence vulnerability? (Nepal)

A
  • Close contact spreads disease/infection, worsened by undernourishment
  • Rural areas have 3 hour walk through mountains to the hospital
  • Patients develop drug resistance and need specialist treatments in the capital city
40
Q

How do income opportunities influence vulnerability? (Nepal)

A
  • Caste structure creates division
  • Many live in stone/mud houses that collapse from EQ tremors
  • Concrete dwellings often occupied by higher caste
41
Q

Local, national and global governance for management (general strategies)

A
  • local: Might organise evacuation strategies
  • national: Finance emergency care or mandate education strategies
  • global: Coordinate a tsunami warning system
42
Q

How isolation, accessibility and degree of urbanisation influence vulnerability (Bam)

A
  • Desert oasis located in isolated part of Southern Iran
  • Nearest major town is 200km away, so difficult to get help quickly
  • Links East and West civilisations (trade route to Pakistan) but not developed/urban itself
43
Q

Spearman’s Rank

A
  • When ranking pairs, if the variable number is the same, use the middle number of the ranks
  • Degrees of freedom is n-2
  • Rank coefficient must be above the critical value to reject null hypothesis
44
Q

What does prediction and forecasting accuracy involve?

A
  • Statistical projections
  • Build models of magma movement/measure EQ stress
  • Can’t have accurate location or timing
45
Q

How does prediction depend on type and location of hazard?

A
  • It costs to change city life
  • Communication between scientists and government being unclear means they can’t do much
  • Persuade govmt to have building regulations and evacuation plans
46
Q

Strategies to modify vulnerability

A
  • High tech monitoring: computer models of ground movement and disaster potential, sensors tag buildings as safe or not
  • Prediction: ShakeAlert (SMS warnings)
  • Education: annual Golden Guardian exercise to simulate EQ
  • Community preparedness: California State Law means multiple people in charge
  • Adaptation: emergency operations centre, 180 seismic retrofits
  • Models forecasting impacts: interdependence between energy and utility systems to get them working asap
47
Q

General EQ management strategies

A
  • EQ proof buildings: more money to reinforce or just repair after collapse
  • Insurance: high EQ chance so high premiums, or take chance to save up and rebuild after
  • High econ cost is a problem, so need to map chance of EQ
  • Move financial services onto internet to continue trading and business when buildings collapse
48
Q

Who needs emergency, ST and LT aid in San Francisco?

A 
800,000 residents
100,000 tourists 
300,000 commuters
20% disabled population 
Homeless population
49
Q

Insurance

A
  • Premiums go up and are more than property value (just pay to rebuild after)
  • Or premiums do not cover cost of damage so insurance companies have to pay for it
50
Q

Role of NGOs in relief

A
  • NGO volunteers can help fire department

- CARD (community agencies responding to disaster) connects nonprofit + private orgs to provide essential items

51
Q

Role of media as an actor

A
  • Media is a non-state actor, but provides short term response, as they provide news immediately and give updates over a few months.
    • Mostly social media, so they need to grab attention quickly over a few seconds, because they are profit orientated
    • Show statistics, damaged areas, and upset people (disaster capitalism)
52
Q

Intra-plate EQs

A

Not on plate boundaries

53
Q

Mantle plumes

A
  • Occur at areas of mantle where magma and heat rises

- Increase in heat and decreased pressure melts lithosphere base (crust)

54
Q

Hot spots

A
  • Magma exploits cracks and accumulates, and sometimes the mantle plume is more intense than usual
  • Volcanoes form and move away as tectonic plate moves over stationary hotspot
  • Sea level rises and cover the volcanoes that have moved away, then fills the crater, growing vegetation and possibly forming coral reefs
  • Leads to atolls, volcanic islands and seamounts
55
Q

Trend in number of deaths, number of affected and econ damage since 1960

A
  • More megacities so more people living in hazardous areas, but number of deaths decreasing
  • 1960 population was less than 3 billion, but now 7.3 billion, so naturally more affected
  • Increased economic costs with more development
  • Main change is hydrometeorological and effects of climate change
56
Q

What are issues with reliability of data to interpret complex trends?

A
  • No agreed definition or how to measure
  • Number of those affected is subjective
  • Methods of reporting have changed so hard to compare with previous data
  • Don’t consider informal economy
  • Understated or overstated by govmt
57
Q

What are factors of a hazard profile?

A

Magnitude, speed of onset, duration, areal extent, spatial predictability, frequency
Profile doesn’t usually include human geo but can choose to add it in

Edexcel A Level Geography (15 decks)

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