tectonic processes and hazards key info Flashcards

1
Q

where are hazards predominantly found

A

where earths major plate boundaries meet -
movement of these plates driven by convection currents in the mantle

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2
Q

what happens at a conservative plate B and what does it cause

A

two plates move past each other in opposite direction or same direction at diff speeds

causes earthquakes

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3
Q

what happens at constructive plate boundaries (divergent) and what do they cause

A

two plates move apart and magma wells to surface

causes earthquakes and volcanoes

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4
Q

what are destructive plate boundaries (convergent) and what do they cause

A

oceanic plate subducts under less dense continental place and oceanic melts and forces its way to the surface as magma

earthquakes, volcanoes, tsunami

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5
Q

what happens at a collision plate boundary and what does it cause

A

2 continental plates move towards each other

fold mountains creating , earthquakes

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6
Q

what does intraplate mean

A

earthquakes or volcanoes in centre of plate

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7
Q

what theory did Alfred Wagner propose

A

-idea of continental displacement
- idea that we were once joined in a super continent called pangea
- parts moved due to continental drift
- theory rejected but in 1950s proven using paleo magnetism

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8
Q

who proposed the idea of the continental displacement

A

Alfred Wegner

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9
Q

what is palaeomagnetism and who found it

A

2 geologists discovered magnetic stripes parallel to the mid atlantic ridge

stripes corresponded to times earths magnetic field reversed

iron in magma lined itself up

supported theory of sea floor spreading

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10
Q

what is the wilson cycle

A

the theory that if continents move apart to form ocean basins, other oceans must close

if land moves apart, must also move together

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11
Q

what are earthquakes and what causes them

A

caused by sudden movements along fault lines proceeded by a build up of strain

when pressure exceeds, rock fractures and sudden release of energy makes ground shake

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12
Q

what are the three types of waves

A

p waves

s waves

L waves

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13
Q

what are the characteristics of P waves

A

vibrations caused by compression

spread quickly

arrive first

less destructive

back and forth motion

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14
Q

what are the characteristics of S waves

A

move slowly

vibrate at right angles to direction of travel

sideways moving and ground goes up and down

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15
Q

what are the characteristics of L waves

A

surface waves vibration occurring in horizontal plane

side to side

high amplitude

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16
Q

what’s the benioff zone

A

area of seismicity corresponding with the slab being thrust down in subduction zone

produces numerous earthquakes

deep focused

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17
Q

what is liquefaction

A

vibrations or water pressure in soil particles lose contact with each other. soil behaves like liquid and can’t hold weight
flows down slopes

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18
Q

what are landslides

A

movement of rock or debris down a sloped section of land

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19
Q

what causes tsunamis

A

series of waves caused by earthquakes or volcanoes

along destructive fault lines

release of friction caused subducting plate to lift

displacing water column above

forms waves - up to 30m

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20
Q

what are lava flows

A
  • streams of lava on surface
  • very hot and takes years to cool
  • not a threat to humans as they move slow
  • destroy everything in path eg homes
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21
Q

what is pyroclastic flow

A
  • mixture of hot rock lava and ash and gas
  • ejected from volcano
  • move extremely fast and destroy anything they touch
  • dangerous
  • very hot and move around 100km
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22
Q

what are tephra and ash falls

A
  • volcanic rock and ash released into air during eruption
  • large heavier peices do not travel as far
  • can cause injury and death
  • ash falls cover everything and poor visibility
  • roofs can collapse due to weight
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23
Q

what are gas eruptions

A

water vapour, co2 and sulphur

can affect people animals and infrastructure

can travel thousands of miles

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24
Q

what are lahars

A
  • masses of rock mud + water
  • move quickly down volcano
  • caused when heat melts snow and ice
  • vary in size and speed
  • can not outrun
  • can also be caused by heavy rain
25
what is jokulhlaup
melts snow and ice heavy sudden flooding
26
what are volcanoes and how are they caused
opening in the earths crust through which lava ash and gas erupts 1900 volcanoes are active
27
how do you measure volcanic eruptions
size and force varies volcanic explosivity index compares and describes magnitude of erruptions from 0 (non explosive) to 8 (extremely explosive) the amount and height ejected , duration are measures
28
how do you predict volcanoes
small earthquakes from magma rising change in shape change in tilt gas- sulphur temp- magma is close to surface or not
29
What is a hazard
A perceived natural event that has potential to threaten life and property
30
what is a disaster
Reality of a hazard happening when it causes significant impact on a vulnerable population
31
what is the relationship between risk hazards and people due to
unpredictability Lack of alternatives which is why people stay Dynamic hazards (made worse by people) Cost benefit of staying in location Russian roulette reaction - the acceptance that the risk is going to be something anywhere they live
32
what is the hazard risk equation and what does it capture
Captures the various components that influence the risk Risk = hazard x exposure x vulnerability ------------------- Manageability
33
what is the PAR model
Pressure and release model Works On the basis that a disaster is the intersection of two processes- processes generating vulnerability and natural hazard event
34
what is a hazard profile and what is it used for
Compares physical processes that all hazards share Identifies and ranks hazards that should be given most attention Use to compare the same hazard in different places Maybe inaccurate
35
why are hazard profiles used/what are they useful for
implement land use zoning Hazard resistant designs Educating locals Community preparedness Management strategies
36
how does governance impact vulnerability
Asset inequality- can't recover and poor quality housing Inequality of public services Political inequality - no recovering Social status inequality - access to income and services
37
what are hazard trends
total number has increased number of deaths from them is falling economic costs have increased total number of people affected is rising reported disasters has risen
38
what are reasons for changes in hazard trends
improvements in monitoring and tech global population increased rapid urbanisation
39
why is disaster data hard to collect
there is an immediate focus on response not collection of data methods vary difficult to gather in remote areas political biased ( always said to be worse if there are tourists there)
40
what are physical causes that increase risk of hazards
torrential rain rapid snowmelt eruptions surface runoff la niña
41
what are the human causes that increase risk
deforestation land use change water management mining and quarrying
42
what is hazard management
where gov and other organisations and emergency responders businesses and community groups work together to protect people from hazard provides help reduce loss of life and property rapid recovery
43
what is mitigation
preventing hazard events identifying potential hazards and taking steps to
44
what is preparedness
preparing to deal with hazard minimising loss of life and property
45
what is response
responding effectively to hazard coping with disaster
46
what is recovery
getting back to normal short term and long term
47
what is the parks model and what does it take into account
shows how countries might respond to hazard event can be used to help plan and understand risk and resilience and prepare for future events takes into account hazards are inconsistent have different impacts have different responses country has its own curve
48
what is the difference between mitigation and adaptatation
mit- avoids or delays or prevents hazard whereas adap- reduces the impact
49
what are the types of adaptation
high tech monitoring crisis mapping modelling hazard impact public education community preparedness
50
what is high tech monitoring
allows advances warnings GIS creates hazard maps early warning systems by using scientific equip mobile phone tech for communication
51
what is crisis mapping
map set up and locals provide info via social media locations plotted on map and put online aid directed used in Haiti
52
what is modelling hazard impact
computer models lean scientists can predict the impact on communities compared to effects of different scenarios
53
what is public education and preparedness
better public awareness reduces vulnerability regularly practicing emergency procedures develop plans
54
what are types of mitigation
land use zoning diverting lava flows hazard resistant designs
55
what is land use zoning
local gov plans to regulate how land in a community should be used helps protect areas at risk risk areas used for farming
56
what is diverting lava flows
path taken by lava is diverted by digging channels can be hard to predict
57
what is hazard resistant designs
designing and constructing safe buildings eg earthquake proof shatterproof glass
58
what are the key players in modifying disaster losses
insurers and gov- insurance money they need to repair communities- locals are first to respond especially in remote areas aid donors- emergency aid short term like shelters and long term like rebuilding NGOs- when local governments is struggling