AS Geography - tectonics

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give an example of a major plate
Eurasian
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give an example of a minor plate
CoCo's
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give an example of a micro-plate
Sunda
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where is most earthquake and volcanic activity found?
in zones along plate boundaries
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what is an intra-plate?
an earthquake near the middle of plates associated with ancient faults
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what is a hotspot?
volcanic activity near the centre of a plate
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how are hotspots formed?
up-welling of hot molten lava from the core or mantle or from the top of a large mantle plume
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what is orogeny?
creating mountains due to tectonic activity
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what is the moment magnitude scale?
measures size of earthquakes in term of energy released, each number you go up the amplitude of ground motion goes up by 10
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what plate boundaries are between Australia and India?
Constructive and collision, the collision boundaries here are located underwater and so create tsunamis
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what can collision plates also lead to?
earthquakes occurring well away from the boundary itself, for example collision plate between indian and eurasian plate, another example is Nepal
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what is convection?
lower mantle gets heated by the outer core and acts like viscous liquid and rises
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what is slab pull?
when magma currents make contact with the lithosphere they move the crust above due to frictional drag
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what are convection currents?
when the material rises and cools and then gets pushed away by the rest of the rising mantle and falls back down, it cause the crust above to move to the sides with it due to it being viscous sticky lava
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what is the benioff zone?
the zone of melting
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what is an accretionary wedge?
parts of material left behind when a plate subducts because it gets shaved off
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is the oceanic plate dense?
yes
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what is an island arc?
chain of volcanoes with arc shaped alignment, parallel and close to boundary, more dense plate subducts
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give an exampple of a trench
peru-chile trench (subduction)
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give an example of a conservative/transform plate boudary
san andreas
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what is a destructive/convergent plate?
when the less dense oceanic plate subducts the more dense continental plate
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what is a constructive/divergent plate?
when both plates move away from eachother causing volcanoes as the magma rises in between
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what is a collision/convergent plate?
both plates moving into eachother creating fold mountains
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what is a transform/conservative plate?
both plates moving together in the same or opposite direction but at different speeds, every now and then they get caught and jolt creating an earthquake
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give an example of a destructive plate boundary
Nazca plate (oceanic) subducting the South American plate (continental)
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give an example of an island arc
Pacific plate (oceanic) subducting australian plate (mostly continental with some oceanic)
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give an example of a constructive plate boundary
pacific plate (oceanic) and Nazca plate (oceanic), Mid Atlantic ridge
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give an example of a collision plate boundary
indian continental plate, Himalayan mountains
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give an example of a conservative plate boundary
Pacific plate (oceanic) and North American plate (continental), San Andreas fault
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what are the characteristics of primary waves?
arrive first, fast, move through solid rock and fluids, compresses in direction of travel
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what are the characteristics of secondary waves?
slower than primary waves, only move through solid rock, up and down movement
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what are the characteristics of rayleigh waves?
only travel through surface of crust, travel in a rolling motion, ground is moved up and down and side to side, responsible for most of the shaking felt by people
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what are the characteristics of love waves?
only travel through surface of the crust, fastest of the surface waves, move from side to side horizontally as it moves forward
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what is pancaking?
floors of buildings fall on top of each other in the event of an earthquake due to them being poorly built, most common in LEDC'S
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what is bathymetry?
the sea floor (relief of sea bottom)
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how do secondary impacts occur?
as a result of primary impacts
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give 3 examples of a secondary impact
tsunami, landslide, liquefaction
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give an example of where liquefaction has occured
Mexico city
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how are tsunamis formed?
form as a result of an earthquake, upthrust along the fault line displaces the water above it known as water column displacement, the energy is transferred through the water in a sequence of waves until they hit the continental shelf at shore.
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what happens when waves hit the continental shelf at the shore?
the friction will slow them down
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are tsunamis noticeable out at sea?
they are barely noticeable
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what can cause tsunamis to slow down?
islands, reefs, ridges and sea mounts
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what can cause waves to differ?
bathymetry, coastlines, continental shelves and tides
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Name two other causes of tsunamis
Explosive volcanism leading to collapse of cone or landslides into sea displacing the water and underwater landslides
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what is liquefaction?
during earthquake shaking sand and silt grains in wet soil get re-arranged and the water in the spaces is squeezed out, pressure builds in the water and the soil is more like a liquid because the grains float in the water
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how do landslides occur?
result of an earthquake, vibrations lead to failure of soil cohesion so it begins to collapse, more common in mountainous areas
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what is the oblique reverse thrust mechanism?
Indicate a shortening of the crust, with the land being pushed up as well as being moved horizontally
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what is a seamount?
huge volcano that grow from the sea floor but do not reach the surface
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what are the characteristics of a strato-volcano?
steep conical profile, The lava that flows from them is highly viscous, and cools and hardens before spreading very far, ave explosive eruptions
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what are the characteristics of shield volcanos?
flat profile, erupt highly fluid lava, which travels further than lava erupted from stratovolcanoes.
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what are the characteristics of a fissure volcano?
a linear volcanic vent through which lava erupts, usually without any explosive activity. The vent is often a few meters wide and may be many kilometers long
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what is a dyke?
when magma pushes its way through cracks to the earths surface but sometimes cools whilst in the cracks
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what are the main hazards from a volcanic eruption?
Lava, tephra, volcanic gas, lahars, pyroclastic flows
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what is tephra?
rock and ash
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what are the characteristics of basaltic lava?
runny, low in silica, high Co2, gentle eruptions
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what are the characteristics of andesitic lava?
thick, high silica, high water content, more explosive
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what are the characteristics of Rhyolitic lava?
coolest of the lavas, highest silica, most explosive
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what are pyroclastic flows?
occur when eruption columns collapse, can travel at 70ph and reach 800 degrees
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what is jokulhaup?
a flood of meltwater washing out from underneath a glacier or ice cap when a volcano becomes more active
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what is the definition of a disaster?
major hazard event that causes widespread disruption to a community or region, need outside help to deal with
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what is the definition of a hazard?
a threat that has the potential to cause loss of life, injury, property damage, socio-economic disruption or environmental degradation
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what is the definition of a hazard event?
occurrence of a hazard, the effects of which change demographic, economic and/or environmental conditions
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what is the definition of a risk?
probability of a hazard event causing harmful consequences, expected loss, deaths, injury's, property damage, economy and environment
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what is the definition of vulnerability?
susceptibility of a community to a hazard or to the impacts of a hazard event
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what is the UNISDR?
united nations international strategy for disaster reduction
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how do you know if an event is a mega-disaster?
2000 deaths or 20,000+ homeless/aid still coming from abroad after a year/gdp of country reducing by 5%
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what does the Moment magnitude scale measure?
the energy released by an earthquake
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what does the Mercalli scale measure?
the intensity of an earthquake
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what is the definition of resilience?
The ability of a system, community or society exposed to a hazard to resist, absorb and recover from its effects
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what is mitigation?
finding way to prepare for hazard events to try and reduce or prevent impacts
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what do the WRI do?
considers measures of exposure, susceptability, coping capacity and adaptive capacity
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what can be the effect of storms after an earthquake?
increase lahars and so may wash away houses and prevent plains from bringing in aid
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what is extreme cold?
exposure to cold weather when all buildings have collapsed in an earthquake
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what are the consequences of strong winds?
stops aid, creates unstable buildings that get knocked over, causes fire to spread after an earthquake
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what is a disaster hotspot?
an area under risk from multiple hazards, large developed cities are most at risk due to having marginal land
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what is marginal land?
land not built on before
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what do the ASCEND project do?
educate people on the different hazardous events
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what are shock absorbers iin ledcs?
tyres filled with stones or sand placed under buildings to absorb the ground motion
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how can volcanic eruptions be modified?
lava diversion barriers, draining crater lakes to reduce risk of lahars, spraying sea water to cool and solidify lava flow
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what is GNS science?
creating HD 3D data of the earths surface to help predict hazardous events
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what is land reform?
relocating ownership to less risky areas
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what is land use zoning?
areas split into zones depending on its use
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what is a good way of predicting what will happen in the event of a hazardous evet?
risk mapping
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what is the most effective way of planning for and predicting hazardous events now?
technology
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what can help create evacuation routes?
improving communication routes
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what are building modifications that can stop buildings collapsing?
counter weight at the top and base isolators at the bottom
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how can you know if a volcano will erupt?
thermal imaging, bulging, gas monitoring, seisometres, small tremors
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what is the hazard management cycle?
a plan of how to prepare and respond to hazards
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what four stages of the hazard management cycle are there?
mitigation, preparation, response, recovery
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what is the mitigation stage?
prevent or minimise hazard events, identify the hazard, help communities become less vulnerable
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what actions take place in the mitigation stage?
zoning and land use planning, developing and enforcing building codes, protective building structures
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what is the preparation stage?
prepare to deal with the hazard, minimise loss of life and loss of property
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what actions take place in the preparation stage?
develop preparation plans, develop early warning signs, create evactuation routes
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what is the response stage?
responding effectively to the event, coping with it, saving lives, protecting property
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what actions take place in the response stage?
search and rescue, evacuating people, restoring water and electricity, ensuring medical care continues
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what is the recovery stage?
getting back to normal either short term or long term recovery strategies
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what does parks disaster model do?
shows how countries or regions might respond to a hazard event, used to understand the time dimensions from disaster time to returning to normal, prepare for future events
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what does it take into account?
hazards are inconsistent, all hazards have different impacts and responses, wealthy countries can recover faster
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who are key players after a hazard event?
local communities, insurance companies, aid donors, government, NGO's
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what is an NGO?
Non-governmental organisation
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who is the first to respond to a disater?
communities
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what is the role of aid donors?
emergency aid, short term aid or long term aid
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what types of aid is there?
cash, personal, services or equipment
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what is a disadvantage of money as a form of aid?
can go missing or just go straight to the government
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what do NGO's do?
provide funds,co-ordinate search and rescue efforts and help
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how many deaths smake a "disaster"
over 500
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what is a primary effect and give an example?
what happens straight away for example a volcano erupting
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what is a secondary effect and give an example?
what happens as a result of the primary impact, for example roads being blocked off due to building collapse after an earthquake
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Other cards in this set

Card 2

Front

give an example of a minor plate

Back

CoCo's

Card 3

Front

give an example of a micro-plate

Back

Preview of the front of card 3

Card 4

Front

where is most earthquake and volcanic activity found?

Back

Preview of the front of card 4

Card 5

Front

what is an intra-plate?

Back

Preview of the front of card 5
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