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Geography 1 > Tectonics > Flashcards

Tectonics Flashcards

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1
Q

What is the shape of the earth?

A

a geoid (bulges in the middle, flatter at the poles)

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2
Q

Why is the earth shaped like this?

A

due to centrifugal forces generated by the Earth’s rotation that fling the molten interior outwards

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3
Q

What is the Earth’s internal structure?

A
  • crust
  • mantle
  • outer core
  • inner core
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4
Q

How thick is the crust?

A

0-100km

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5
Q

How thick is the mantle?

A

2900km

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6
Q

How thick is the outer core?

A

2200km

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7
Q

How thick is the inner core?

A

1270km

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8
Q

What is the temperature and properties of the crust?

A

solid, 900°C

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9
Q

What is the temperature and properties of the mantle?

A

liquid peridotite, 1,600°C

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10
Q

What is the temperature and properties of the outer core?

A

liquid iron and nickel, 4,000°C

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11
Q

What is the temperature and properties of the inner core?

A

solid iron and nickel, 6,000°C

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12
Q

What are the two types of plates that the crust is made up of?

A

continental plates - thicker (up to 100km) less dense, sial (silica/aluminium)
oceanic plates - thinner (approx. 20km) denser, sima (silica/magnesium)

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13
Q

What is the lithosphere and asthenosphere?

A

lithosphere is the 100% solid layer of the earth (i.e. the crust)
asthenosphere can be semi-molten or molten and includes the bottom of the crust

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14
Q

How do convection currents work?

A
  1. at over 1000°C, peridotite in the mantle near the core is under extreme pressure and heat
  2. this peridotite becomes “plastic” (behaving like a viscous liquid) and flows upwards to the surface
  3. the high pressure of rocks in the crust stops them from melting as the peridotite reaches them, instead the peridotite cools and flows sideways before returning to the core
  4. this movement forms a convection current; the sideways movement of rocks just beneath the crust causes tectonic plates to move
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15
Q

What did Alfred Wegener suggest?

A

in 1912, Wegener suggested his theory of continental drift - belief that all continents were originally joined as one landmass an slowly drifted to their current position

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16
Q

What 6 pieces of evidence did Wegener base his theory of continental drift on?

A
  1. the shape of Africa fit into South America
  2. mountain range in Argentina and South Africa fit
  3. similar Mesosaurus fossils only found in SW Africa and Brazil
  4. same rock type in NW Scotland and Eastern Canada
  5. coal found in Antarctica (showed warmer latitude)
  6. glacial deposits and striations matched in Brazil and West Africa
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17
Q

How did Harry Hess add to Wegener’s theory?

A

in 1962, Hess put forward his theory of Plate Tectonics - discovered sea-floor spreading (that new ocean crust was being continually created along mid-ocean ridges as the crust moves apart) - this was established as the driving force of the movement of continents

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18
Q

How did Harry Hess support his theory?

A

using palaeomagnetism - every 400,000 years the Earth’s magnetism flips - particles in iron oxide called magnetite always move towards north, therefore different rocks have differently positioned minerals that reflect their age - used to prove the creation of new rock

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19
Q

What is slab pull?

A

slab pull - when denser oceanic plates are subjected at cold downwellings, this may cause mantle ares to be cooler and the downward movement within convection currents
e.g. the Pacific Plate has lots of subduction at its edge - this may be why it moves faster than other plates

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20
Q

How did the earth change from Pangaea to present day?

A
  1. permian - 250 million years ago (all continents joined as one super-continent called Pangaea)
  2. triassic - 200 million years ago (Pangaea split into Laurasia and Gondwanaland)
  3. Jurassic - 145 million years ago (continental landmasses continue to drift apart)
  4. Cretacious - 65 million years ago (South America and Africa separate)
  5. Present day (India has crashed into Asia)
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21
Q

What are the types of plate boundaries?

A
  • divergent/constructive
  • convergent/destructive
  • conservative/transform
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22
Q

What happens at continental divergence?

A
  • two continental plates move apart
  • the land is too thick for magma to rise through the gap in the plates, and magma is too viscous, so the land between each fault collapses forming rift valleys
  • e.g. Iceland rift valley where the Eurasian and North American Plate move apart
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23
Q

What happens at oceanic divergence?

A
  • two oceanic plates move apart
  • magma that is not very viscous flows to the surface, forming gently sloping shield volcanoes
  • e.g. Surtsey - shield volcano formed an island in 1963, located on the SW coast of Iceland now with a functioning ecosystem
  • ocean ridges also form - huge ranges of submarine mountains that do not remain volcanic, can be up to 4000m high but still completely submerged
  • e.g. Mid Atlantic Ridge
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24
Q

What happens at continental convergence?

A
  • two continental plates move towards eachother
  • plates have a lower density than the asthenosphere below them, therefore do not subduct
  • colliding plates are uplifted and buckle high to form fold mountain ranges
  • e.g. Himalayan Mountains, Nepal (Indian and Eurasian plate)
  • the lava is more viscous as the thick crust means gases are absorbed as it travels upwards - means no volcanic activity occurs
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25
Q

What happens at oceanic convergence?

A
  • two oceanic plates move towards eachother
  • the fastest moving or more dense plate subducts, forming deep ocean trenches and melting
  • benioff zone: zone where friction and high temperatures cause melting, leading to tension and earthquakes, 100-700km deep
  • rising magma from the benioff zone causes crescents of submarine volcanoes along the plate margin
  • these crescents may grow into island arcs e.g. Mariana’s trench (where Philippine Plate subducts under the Pacific Plate)
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26
Q

What happens at oceanic-continental convergence?

A
  • an oceanic and continental plate move towards eachother
  • the denser oceanic plate subducts under the lighter continental plate
  • the oceanic plate reaches the benioff zone and starts to melt, the magma is less dense so rises in plumes through the continental plate
  • this causes composite cone volcanoes to form from the andesite lava (viscous lava as gases are absorbed)
  • the continental plate is uplifted to form chains of fold mountains e.g. the Andes
  • ocean trenches may also form eg Mariana’s Trench
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27
Q

What happens at Conservative Plate margins?

A
  • two plates move side by side - either in different directions or the same direction at different speeds
  • earthquakes occur as a result of locked faults (when friction between plates leads to a build up of stress)
  • e.g. San Andreas fault line, California (North American and Pacific Plate)
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28
Q

What is movement of conservative plates called?

A

movement to the left - sinistral

movement to the right - dextral

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29
Q

When do hot spots form?

A
  • a hot spot forms when a stationary mantle plume breaks through a weak part of the crust
  • on an oceanic plate - shield volcanoes form with basalt lava e.g. Mauna Foa
  • on a continental plate - composite cone volcanoes form in a “vulcanian” style eruption, with andesite lava that erupts over 17km high, tephra and pyroclastic flows reach 700km/h
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30
Q

What is an example of a hot spot?

A
  • Hawaii
  • movement of Pacific Plate over the stationary Hawaiian hot spot has created a long trail of volcano chains comprising of 80 volcanoes, 3200km from the nearest plate boundary e.g. Hawaiian Ridge-Emperor Seamounts that extend 6,000 km
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31
Q

What are the types of seismic waves?

A
  • primary/pressure (p) waves
  • secondary/shear (s) waves
  • surface/love waves
  • Rayleigh waves
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32
Q

What are the features of primary/pressure waves?

A
  • first to surface
  • fastest wave at 8km/s
  • push waves
  • moves through solids and liquids
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33
Q

What are the features of secondary/shear waves?

A
  • slower - 4km/s (half the speed of p waves)
  • shake sideways
  • only travel through solids
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34
Q

What are the features of surface/love waves?

A
  • shake sideways

- slowest and most dangerous

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35
Q

What are the features of Rayleigh waves?

A
  • complex rolling motion that radiates from the epicentre
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36
Q

Where do earthquakes occur?

A
  • 5% intraplate earthquakes associated with weaknesses in Plates (created as plates move over a spherical surface) that become re-activated e.g. New Madrid, Missouri 1811
  • 95% occur at plate margins
    divergent: frequent, small, low hazard, take place in the ocean but don’t trigger tsunamis
    convergent: dangerous, sometimes subduction zones or collision zones form, friction/pressure released as seismic waves e.g. Japan 2011 earthquake
    conservative: higher risk e.g. San Andreas
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37
Q

How do physical processes impact on earthquake magnitude and focal depth?

A
  • type of plate boundary (impacts on magnitude and focal depth)
  • pre-existing weaknesses in plates
  • existence of benioff zones (zones of increased earthquake activity produced by the subduction of an oceanic plate under a continental one)
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38
Q

In what ways can earthquakes be mitigated?

A
  • prediction methods
  • government planning
  • individual preparation
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39
Q

What are the prediction methods of earthquakes? (10)

A
  • animal behaviour
  • radon gas
  • increase of argon gas in soil
  • microquakes
  • bulging of the ground
  • electrical/magnetic change in rocks
  • magnitude-frequency analysis
  • seismometer
  • spread measure
  • aerial photography
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40
Q

What government planning can be used for earthquakes? (4)

A
  • aseismic building regulations
  • warn citizens
  • evacuation drills (e.g. 1st Sept in Japan)
  • early warning systems e.g. texts
41
Q

How can individual preparation mitigate earthquakes? (4)

A
  • pack emergency kits
  • first aid training
  • stock up on supplies
  • partake in drills at the workplace or in schools
42
Q

In what ways can a building be made aseismic? (8)

A
  • counterweights
  • hollow bricks
  • verti scapes
  • emergency arrows/lights
  • emergency shutters
  • triple-glazed windows/safety glass
  • deep or reinforced foundations
  • cross bracing
43
Q

What are the impacts of earthquakes?

A
  • primary hazards e.g. ground shaking, surface rupture, landslides and liquefaction (water-saturated material loses strength and behaves like a liquid under pressure e.g. Christchurch 2011)
  • secondary hazards e.g. tsunamis, seiche (flooding in a lake), fire (e.g. Haiti’s power cables), landslides from weakening and falling of sediment
44
Q

What percentage of earthquake deaths are from landslides?

A

70% of earthquake deaths over last 40 years

45
Q

What are the factors that affect the consequence of earthquakes?

A
  • magnitude/depth of epicentre
  • distance from epicentre
  • geological conditions
  • population density, preparation and education
  • time of day
  • impact of indirect hazards
  • design/strength of buildings, government and development
46
Q

What are the two case studies used to demonstrate why some areas have larger consequences of earthquakes than others?

A
  • Afghanistan earthquake 25th March 2002

- Taiwan Earthquake 30th March 2002

47
Q

Why did Afghanistan suffer more than Taiwan in their 2002 earthquakes? (7 reasons)

A
  • epicentre of Taiwan not near built-up areas
  • Taiwan houses equipped to withstand earthquakes - stronger more modern
  • Taiwanese educated in what to do in the event of an earthquake
  • Taiwan had appropriate resources for aftermath and was not drought stricken and in a war zone
  • Taiwan significantly more wealthy
  • Taiwan’s earthquake was less shallow
  • Taiwan’s earthquake was not near the water table so buildings were less vulnerable
    (vice versa)
48
Q

What are natural hazards and when do hazards become disasters?

A
  • hazards are natural processes with the potential to affect people
  • hazards become disasters if they strike a vulnerable population that can’t cope using its own resources
49
Q

What scales can be used to measure earthquakes?

A
  1. richter scale - measures madnitude based on logarhythmic scale from 1-10
  2. mercalli scale - measures intensity of damage based on observations from 1-12 with 12 being catastrophic
50
Q

What are the human factors that affect vulnerability and resilience to natural hazards?

A
  • governance (e.g. building regulations, quality of infrastructure, disaster preparedness plans, emergency services, communication systems, public education and practised responses, corruption)
  • socio-economic conditions (level of wealth, access to education, communities with poor healthcare, lack of income opportunities)
  • physical and environmental conditions (high population density, rapid urbanisation, accessibility of the area)
51
Q

What was Japan’s earthquake?

A
  • 11th march 2011 Honshu Earthquake, triggered a tsunami with waves reaching 10m high
  • subduction of the Eurasian plate under the Pacific Plate
  • caused the Fukushima Nuclear Power Plant to be damaged - 20km exclusion zone still exists
52
Q

How was Japan prepared for the Honshu earthquake?

A
  • good infrastructure: strict building regulations promote aseismic - 75% are constructed with earthquakes in mind, low corruption means this is enforced
  • vulnerable areas had 10m high walls, evacuation shelters and marked evacuation routes
  • earthquake emergency kits in homes
  • early warning system detected earthquake a minute in advance
  • education e.g. emergency drills practiced 1st sept every year
53
Q

What was the response to the Honshu earthquake/tsunami?

A
  • gov deployed 110,000 troops within 24 hours
  • all radio/tv switched to earthquake coverage telling people what was happening and what they should do
  • bank of japan offered $183 billion so banks could keep operating (protected the economy)
  • help from 20+ countries
  • 19,000 temporary housing units planned by the end of the month for fukushima
  • 50 nuclear reactors closed
  • 163 countries offered assistance
54
Q

What were the impacts of the Honshu earthquake/tsunami?

A
  • 15,800 deaths
  • 341,000 evacuees - including from nuclear exclusion zone
  • 170,000 houses without running water
  • 46,000 buildings destroyed
  • $235 billion estimated (most costly natural disaster)
  • 50 nuclear reactors closed subsequently
  • 644 companies bankrupt by the following year
  • 5 million tonnes of debris into the sea
  • 110,000 nesting birds killed by tsunami
  • radioactive water near power plant had 4385x more radiation than maximum safety levels
55
Q

What does the risk-poverty nexus suggest?

A 
global processes (e.g. uneven development) -> underlying risk drivers (lack of governance)->
every day risks->extensive/intensive risks->disaster loss->poverty outcomes->multi-dimensional poverty(->every day risks)
56
Q

What was Chile’s earthquake?

A
  • 2010 when the Nazca Plate subducted under the South American Plate
  • tremors shook the capital Santiago for 1 1/2 minutes
  • affected 6 regions holding 80% of the population
57
Q

What were the effects of the Chilean Earthquake 2010?

A
  • 1.5 million without water or electricity
  • cost of rebuilding Chile took up 20%
  • 800 died
  • 500,000 homes destroyed
  • coastline lifted 8 feet due to subduction
58
Q

What makes a community vulnerable?

A 
- micro: 
poor quality building foundations
emergency kits
first aid training
risk map of hazard zones (hazard zoning)
- macro:
mainstream risk assessment
no evacuation drills
lack of building regulations
lack of education
no national disaster plans
no back up generators
corruption
59
Q

How did they predict the Haiti earthquake 2010?

A
  • monitoring stations with bench markers
  • GPS tracker used - movement of 30cm to the east
  • elastic energy measured
  • logarhythmic scale used (richter scale)
  • MEDCs use sensors that measure changes in shape and pressure change
60
Q

What is the LEDC earthquake case study?

A

nepal earthquake 25th april 2015 when the indo-australian plate subducted the eurasian plate

61
Q

What were the impacts of Nepal’s earthquake 2015?

A
  • 9,000 died
  • 600,000 structures damaged
  • 3.5 million made homeless
  • tourist flow decreased 72%
  • total damage costs at $10 billion nearly half of its GDP
  • 2.2% of direct cover lost in affected areas
  • ground cracks in 31 districts
62
Q

What were the responses to Nepal’s earthquake 2015?

A
  • 90% of the nepalese army sent to stricken areas
  • reliance on international aid eg the red cross, indian gov supplied $1 billion and distributed 100,000 bottles of water daily
  • after a year only 5% of homes had been rebuilt
  • 2 and a half years later only 12% of reconstruction money was distributed
63
Q

Why is it difficult to predict whether an earthquake will cause a tsunami?

A
  • lack of ways to predict earthquakes means there’s no way to predict tsunami
64
Q

What’s the difference between the water column and the tsunami?

A
  • the water column is the uplift of the water where as tsunami is the wave
65
Q

What is the Dart System?

A
  • system of predicting tsunami
  • seabed sensors and surface buoys monitor changes in sea level/pressure - tsunami waves detected - info sent to tsunami warning stations via satellite - computer monitoring used to estimate size/direction - warning signals given
66
Q

What are the different hazard-mitigation strategies?

A
  • land-use zoning (protects people in poverty and property)
  • diverting lava flows (however path of lava is hard to predict)
  • GIS mapping (identifies evacuation routes but only gives rough population size)
  • Hazard-resistant design and engineering devices (buildings that withstand hazards are designed but these are sometimes too expensive for LEDCs)
67
Q

What are the different hazard-adaption strategies?

A
  • high-tech monitoring (allows for advanced warning systems but only prevalent in MEDCs)
  • crisis mapping (allows accurate mapping providing a basis to improve infrastructure but relies on tech
  • modelling hazard impact (allows prediction of the impacts of hazards but relies on tech)
  • public evacuation (improves awareness to improve protection but inconsistent throughout the country)
68
Q

what’s the difference between hazard-mitigation strategies and hazard-adaption strategies?

A

hazard-mitigation strategies - planning for a hazard

hazard-adaption strategies - how you deal with the aftermath

69
Q

What roles do aid donors, NGOs, insurance and communities play in managing loss?

A

aid donors - help countries recover/rebuild especially most vulnerable, however may create dependency on foreign support/aid may not be distributed correctly
NGOs - provide funds, co-ordinate search-and-rescue and reconstruction plans
insurance - provides money needed to repair but few have it and it’s unaffordable to LEDCs
communities - allow for immediate support e.g. search and rescue, but many are unable to cope

70
Q

When does displacement of water (causing a tsunami) occur?

A
  • when volcanoes erupt underwater
  • submarine mountain ranges have landslides
  • an earthquake occurs
71
Q

What are the properties of tsunamis?

A

low amplitude - 0-5-5m
long wavelengths - 150-1,000km
high velocities - up to 600km/h

72
Q

How do tsunamis form?

A
  • rapid movement of the ocean floor displaced a column of water
  • this causes a series of waves to travel outward at heights less than 3 feet on the open
  • these waves increase rapidly in height upon reaching shallow water
  • a drawdown occurs, a trough in front of the tsunami which results in a reduction in sea level
  • as water depth decreases, friction between the wave and see bed causes the wave to slow down, causing wavelength to decrease but wave height to increase
73
Q

What do the characteristics of a tsunami depend on when reaching land?

A
  • the height of the waves and distance they’ve travelled
  • the length of the event
  • coastal physical geography
74
Q

Where do 90% of all tsunamis occur?

A

within the Pacific basin - therefore associated with Plate margins

75
Q

What are the ways of predicting tsunamis? (mitigation methods)

A
  • deep ocean buoys to measure water depth
  • DART (pressure recorders on sea bed detect changes in overlying water pressure) e.g. Pacific Tsunami Warning Centre (9/10 tsunamis occur in this region)
  • tsunami centres built in MEDCs provide protection
  • triple glazing, safety glass, education etc
76
Q

What are the human and physical factors that influence the impact of a tsunami?

A
  • the duration of the event
  • the wave amplitude, water column, displacement and distance travelled
  • physical geography of the coast e.g. water depth/gradient at the shoreline
  • degree of coastal ecosystem buffer e.g. protection of mangroves
  • timing of the event and quality of warning systems
  • degree of coastal development and proximity from the coast
77
Q

What are the two tsunami casestudies?

A
  • MEDC: Japan 2011 Honshu mentioned above
  • LEDC: Boxing Day Tsunami 2004 - Indian Ocean, following earthquake, 7000 killed in Nicobar Islands, hit Sri Lanka 2 hours later, Maldives in 4 hours, then East Africa with one death in Kenya - 1.7 million displaced 283,000 final death toll, Indonesia suffered most with over 100,000, its province Aceh lost 40% lives and damaged fishing/agriculture industry, 30% coral reefs damaged in Indonesia, 50% sandy beaches on West coast, total damage worth $15 billion, aid response of $6.25 billion from UN fund, Japan biggest donor with $500 million and deployment of 100 emergency workers (heavy reliance in LEDCs for aid)
78
Q

What is the difference between a hazard and a disaster?

A
  • hazard: a perceived natural/geographical event that has the potential to threaten life and property
  • disaster: a serious distraction of the functioning of a community involving widespread human/material/economic/environmental losses which exceed the ability of the community to cope using its own resources - UN constitutes disaster as 500+ deaths
79
Q

What does the Swiss Cheese Model/cumulative effect model do?

A

use of cheese analogy - protective barriers e.g. strong governance, with holes allowing the hazard through to become a loss

  • links to mitigation methods and disaster response
    e. g. NZ addresses this well as a multiple-hazard zone with only 3 deaths per year
80
Q

What does Park’s Disaster Response Curve do?

A

shows how quality of life changes in the event of a disaster
stage 1 - pre-disaster (normality)
stage 2 - hazardous event (deterioration)
stage 3 - search/rescue/care (decline lessens)
stage 4 - relief/rehabilitation (recovery process, life improves)
stage 5 - reconstruction in which MEDCs may see improvements

81
Q

What does the Pressure and Release Model show? (Disaster Crunch Model)

A
  • disaster occurs as the result of pressure from processes that generate vulnerability (progression to vulnerability: root causes e.g. access to infrastructure -> dynamic pressures e.g. lack of training -> unsafe conditions e.g. local economy), against pressure of the natural hazard event e.g. earthquake
82
Q

What are the factors involved in the relationship between a hazard and its wider context (incl people)?

A
  • unpredictability (people may be caught out by timing/magnitude)
  • lack of alternatives (people stay in hazardous areas due to lack of other options e.g. for economic reasons, lack of space or lack of knowledge)
  • dynamic hazards (threat of hazards is not consistent over time and may increase/decrease, human influence can influence frequency/magnitude of hazardous events)
  • cost-benefit analysis (benefits of hazard may outweigh risks involved staying in a location, perception of risk may be lower than actual risk)
  • russian roulette reaction (acceptance of risk as something that will happen regardless of what you do)
83
Q

What does disaster ‘resilience’ refer to?

A

community ability to ‘spring back’ from disaster and largely depends on facilities, resources, support and organisation of communities

84
Q

What does the disaster risk and age index highlight?

A

highlights two important trends:

  • ageing populations (more vulnerable e.g. Japanese tsunami 2011, 56% killed were over 65)
  • acceleration of risk in a world increasingly exposed to range of hazards
85
Q

What is the Goma Casestudy?

A
  • Goma, Democratic Republic of Congo - situated on volcanic landscape
  • last eruption in 2002, destroyed 40% of the city
  • area has fertile soils, lots of farming potential
  • 2 million live in area and could be in immediate danger from eruption
  • volcano observatory has since been put in place (links to Swiss Cheese/Parks models) and money investment from UN - but being stolen due to conflicts in area, meaning it has been necessary to put full time armed guard on site
  • constant plume of toxic gas and acid rain common meaning water is not potable
86
Q

What are the primary/secondary impacts of volcanoes?

A

primary impacts
- lava flows (1000-2000 degrees, largest ever recorded in iceland 1783 which killed 100,000s of livestock from poisonous gases, death of 20% surrounding population from subsequent famine from blocked sun)
- volcanic gases and ash falls - Volcanic Ash Advisory Centres monitor clouds
- tephra (ejected rock fragments)
- pyroclastic flows (current of hot gas and volcanic matter - reach speeds of 700km/h)
secondary impacts
- lahars (volcanic mud flows)
- jokulhlaups (glacial outburst floods from subglacial eruptions e.g. Iceland’s 2010 eruption saw discharge flow of 3,000 m3/s)

87
Q

How can physical processes impact on the magnitude and type of volcanic eruption?

A
  • type of volcano e.g. composite cone volcanoes have “vulcanian” style eruption, with andesite lava that erupts over 17km high, tephra and pyroclastic flows reach 700km/h (viscous, violent/explosive, higher gas content)
    shield volcanoes erupt runny basalt lava with low viscosity and gentle energy, low gas content
  • type of lava erupted e.g. basalt/andesite
88
Q

What is the LEDC volcanic eruption casestudy?

A
  • Chaiten eruption 2008, Chile, when Nazca Plate was subducted under South American Plate, causing melting/magma production that rose to surface
  • social impacts: 1 death, 4000 evacuated as ash covered Chaiten town, lahars 1m high surrounded towns and blocked roads
  • economic impacts: airports within 2300km closed, losses of $700,000 for airlines, emergency rescue costs at $36 million
  • environmental impacts: lahars blocked rivers causing flooding, ash fell 15cm deep (killing animals)
  • responses: prompted development of volcano prediction systems, USA helped to monitor, town slowly recovering with current population of 900
89
Q

What is the MEDC volcanic eruption casestudy?

A
  • Eyjafjallajokull eruption 2010, caused by movement of Eurasian and NA plates away from eachother, magma rose through gap creating several active volcanoes
  • social impacts: 500 members of farming community evacuated overnight, 10 million travellers affected by ash cover, cause of respiratory problems of those in Southern areas worst hit
  • economic impacts: airlines lost £130 million a day in revenue, £1.7 billion loss to travel industry, export/imports fell, however ‘volcano tourism’ became popular
  • environmental impacts: 3mm ash layer poisoned animals and contaminated water supplies, measure of 6 degree temp rise in nearby river
  • responses: 60 Icelandic Red Cross volunteers provided food for farming population, counselling and psychological support to those affected, Icelandic authorities recommended sheltering indoors and putting livestock inside
90
Q

What does the Mercalli Intensity Scale do?

A

measures the intensity of shaking produced by an earthquake on a scale of I-X

91
Q

What does the Moment Magnitude Scale do?

A

seismic magnitude scale used to measure the size of an earthquake based on its seismic movement

92
Q

What does the Volcanic Explosivity Index do?

A

measures the explosiveness of volcanic eruptions by classifying them on scale of 0-8 based on characteristics e.g. frequency, plume height

93
Q

What do hazard profiles do?

A
  • show main characteristics of different types of tectonic hazards
  • can be used to help govs to develop disaster plans and mitigate against future hazards
94
Q

What are the recent trends in hazards?

A
  • no of hazards have increased since 1960
  • due to increase in prediction methods, population increase ie people now live in areas previously uninhabited, and population density increase
95
Q

What is a multiple hazard zone?

A
  • area that receives multiple hazards
  • Auckland with 55 volcanoes and population of 2 million, Christchurch 300,000 at flooding risk, Alpine Fault seismically-active
  • e.g. New Zealand, considered leader in effective hazard management with average of 3 deaths a year
96
Q

What does the Hazard Management Cycle do?

A

cycle of: mitigation -> preparedness -> response -> recovery

- shows that better mitigated countries have better recovery

97
Q

What are some hazard management strategies?

A
  • hazard mapping/zoning
  • aseismic building regulations (counterweights, emergency lights, safety glass, vertiscape, cross-bracing)
  • governance (basic first aid, education, drills)
98
Q

How can the different tectonic hazards be predicted?

A
  • volcanoes: observatories in place, magnitude-frequency analysis, temperature probes, spectrometer, animal behaviour
  • earthquakes: seismometers, magnitude-frequency analysis, radon gas, animal behaviour, aerial photography, GPS benchmark tracking
  • tsunamis: deep ocean buoys, DART pressure recorders, Pacific Tsunami Warning System, seismometers

Geography 1 (4 decks)

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