Tectonic processes and hazards Flashcards
(157 cards)
1
Q
The global distribution of earthquakes, tsunamis and volcanoes is linked to what?
A
Plate boundaries
2
Q
What are the different types of plate boundaries?
A
Divergent, convergent, transform and collision
3
Q
What is a divergent plate boundary?
A
Where two plates (usually oceanic) move away from each other
4
Q
Give an example of a divergent plate boundary
A
Between the Nazca and Pacific plates
5
Q
What is a convergent plate boundary?
A
Where an oceanic and continental plate converge, and the oceanic crust subducts
6
Q
Give an example of a convergent plate boundary
A
Along the west coast of South America
7
Q
What is a transform plate boundary?
A
Where two plates move alongside each other, either in opposite directions or same direction at differing speeds
8
Q
Give an example of a transform plate boundary
A
Between the Pacific and North American plates
9
Q
What is a collision plate boundary?
A
When two continental plates converge
10
Q
Give an example of a collision plate boundary
A
between Altiplano and South American plates
11
Q
At what types of plate boundary do volcanoes occur?
A
Divergent and convergent plate boundaries
12
Q
At what types of plate boundary do earthquakes occur?
A
Divergent, convergent, transform and collision
13
Q
At what types of plate boundary do tsunamis occur?
A
Divergent, convergent, transform and collision
14
Q
What is an intra-plate process?
A
A process that occurs towards the middle of the plate rather than the boundary
15
Q
How do intra-plate earthquakes occur?
A
Small movements along fault lines (cracks in the plate caused from previous plate movements) build up friction and strain over time, which is suddenly released, causing low magnitude earthquakes
16
Q
How do intra-plate volcanoes occur?
A
Magma rising through the mantle from the edge of the outer core is able to melt its way through, forcing molten material to the surface, therefore creating volcanoes
17
Q
Name and describe the intra-plate earthquake case study
A
UK
-The UK experiences minor earthquakes despite being 1500km from the nearest plate boundary under the centre of the Atlantic Ocean
-There are about 25 earthquakes in the UK each year that are felt by people
-The largest occurred in 1931 under the North Sea at Dagger Bank
-6.1 on the Richter scale
18
Q
Name and describe the intra-plate volcano case study
A
Hawaii
-The Hawaiian islands have 15 volcanoes, which are the youngest of 130 found along a 6000km line to their north-west
-Kilauea and Mauna Loa are the most active volcanoes on the planet
-The submarine volcano Lo’ihi is the youngest in the Hawaiian chain, being created as the Pacific plate moves north-westwards over the hotspot
19
Q
Where are the two massive mantle plumes in the Earth’s mantle layer?
A
Under the Pacific plate, and under the African plate
20
Q
What is a mantle plume?
A
An area under the crust, where magma is hotter than surrounding magma
21
Q
How are hotspots created?
A
Erupted mantle plumes once broken through the crust will form hotspots
22
Q
What are the four layers of the earth, from innermost to outermost?
A
Inner core, outer core, mantle, crust
23
Q
What are the 4 components of plate tectonic theory?
A
1) Characteristics of the Earth’s structure
2) Mantle convection
3) Palaeomagnetism and sea floor spreading
4) Subduction and slab pull
24
Q
A
25
Evaluate mantle convection (Plate tectonic theory)
-Heat radiating from the inner core causes it to convect
-Convection may be in several layers or just one
-The convection cells make contact with the base of the crust which causes friction
-Friction drags the crust along in the general direction of the convection
26
Evaluate palaeomagnetism and sea floor spreading (Plate tectonic theory)
-The outer core is mostly liquid and it convects; this movement creates a magnetic field for the earth
-When new igneous rocks cool to solidify, they trap in the magnetic field direction
-Geological records of magnetic directions are symmetrical either side of divergent plate boundaries
-This proves that the oceanic crust has been diverging in places for a long time
27
Evaluate subduction and slab pull (Plate tectonic theory)
-At subduction zones (convergent boundaries), as the oceanic plate subducts it pulls the rest of the plate down with it
28
At what type of plate boundary are seismic waves the greatest?
Convergent plate boundaries
29
What is a body wave?
A wave that travels through the Earth
30
What is a surface wave?
A wave that travels through the top of the crust
31
What are the 2 types of body waves?
Primary (P) waves and Secondary (S) waves
32
Describe characteristics of Primary (P) waves
Arrives first, fast, moves through solid rocks and fluids, pushes and pulls in the direction of travel
33
Describe characteristics of Secondary (S) waves
Slower than P waves, only moves through solid rock, up and down movement
34
Describe characteristics of Love (L) waves
Only travels through the surface of the crust, fastest of the surface waves and moves from side to side as it moves forward
35
Name 4 hazards caused by earthquake waves
1) Crustal fracturing
2) Ground shaking
3) Liquefaction
4) Landslides
36
Describe crustal fracturing
-Primary hazard
-Shockwaves travel fast through solid rock and can increase stress in it
-Stress causes strain until the rock fractures
37
Describe ground shaking
-Primary hazard
-Shockwave ground movements include:
Pushing and pulling (P)
Up and down (S)
Side to side (L)
38
Describe liquefaction
-Secondary hazard
-Occurs when shockwaves travel through loose unconsolidated material, shaking it so it acts like a fluid
39
Describe landslides
-Secondary hazard
-Occur when there are steep slopes
-The shockwaves loosen rock and cause it to move downslope under the influence of gravity
40
Give an example of when/where liquefaction has occurred
Christchurch, 2011
41
Give an example of when/where a landslide has occurred
Kashmir, 2005
42
Why can L waves be the most damaging?
They arrive after P and S waves have already weakened buildings
43
What are some effects of crustal fracturing?
Causes faults, which can rupture the surface
Anything on these faults can get moves and damaged
44
What are some effects of ground shaking?
Buildings that are not aseismic may only survive some types of shaking, and will be damaged
45
What are some effects of liquefaction?
Causes buildings to tilt over or collapse and the ground to crack
Underground infrastructure such as cables and pipes may be ruptured
46
What are some effects of landslides?
Landslides may hit settlements directly or destroy/block transport and communication infrastructure
47
What are 6 hazards that a volcanic eruption could cause?
1) Ash falls
2) Pyroclastic flows
3) Gas eruptions
4) Lava flows
5) Lahars
6) Jokulhaulps
48
Describe the characteristics and effects of ash falls
-Ash are forced to a high altitude and are so light that they can be carried around the planet in the atmosphere
-A lot of ash can fall locally which causes roofs to collapse
-It gets into machinery and causes them to collapse
-Ash clouds disrupt flight paths of aeroplanes as it damages engines and fuselages
49
Describe the characteristics and effects of pyroclastic flows
-Considered the most dangerous
-Flows consist of a dense mixture of superheated solid particles and poisonous gases
-These move down the slopes with speeds of up to 700km/h
-Any buildings or people in the way are destroyed by impact/burying/incineration/poisoning
-The deposition of material may also block river channels and cause flooding
50
Describe the characteristics and effects of gas eruptions
-Water vapour (a common volcanic gas) is condensed locally with other erupted material (lahars)
-Other gases include sulphur dioxide which is poisonous in high concentrations and can cause 'acid rain' when combined with water vapour
-SO2 may also cool the Earth when carried high into the atmosphere, blocking the suns energy; historical eruptions have caused crop failures/famine this way
51
Describe the characteristics and effects of lava flows
-Erupted molten magma flows down the sides until it cools
-Buildings/infrastructure cannot move out of the lavas path, so the lava sets fire/buries them
52
Describe the characteristics and effects of lahars
-A mixture of water and erupted volcanic material which flow fast (60km/h) down river valleys
-Water may come from rainfall/crater lake/melting of a snow cap on the top of a volcano
-Poses a risk to settlements as they are deceptively fast, so people struggle to escape
53
Describe the characteristics and effects of jokulhlaups
-Where a volcano erupts under an ice cap, and so this cap is melted
-The melted water is trapped by remaining ice, so when the remaining cap is lifted by the meltwater the water bursts out from under the ice and flows rapidly to the ground
-When this happens anything in its path is washed away or covered by volcanic and glacial deposits
54
What causes a tsunami?
Submarine earthquakes at subduction zones that displace a column of seawater, which causes a tsunami
55
Give 4 features of a tsunami
1) A sequence of large waves of varying heights
2) Long wavelength in open ocean, but short in shallow water
3) Very fast speeds in deep water but slower in shallower
4) Low height in open ocean but significant height in shallow water
56
How do tsunamis form?
-An undersea earthquake at a subduction zone that causes a rapid movement of the sea bed
-If this movement is up and down, then a column of seawater above the epicentre is displaced
-This creates a powerful wave motion
57
Name and describe the tsunami case study
Tohoku, 2011
-Undersea earthquake at junction of Pacific and Okhotsk plates
-Mw 9.0.
-Lowland east coast of Japan only 130km away from epicentre facing the tsunami
-18,500 killed
-$220 billion of damage, including failure of nuclear power plants and release of radioactivity
-Category VI (highest) on the Tsunami Intensity Scale
-Tsunami reached Hawaii about 8.5 hours later
58
Define a natural hazard
A natural event that causes a disruption to daily lives or death and disruption
59
How is the scale of a disaster measured?
By the number of deaths (500+) or the cost of damage (millions of $)
60
Define a mega-disaster
A disaster that has over 2000 deaths and a GDP reduction of over 5%
61
Define the term adaptation
Changes to ways of doing things so future hazards have less impact
62
Define the term recovery
Ways of returning to normal after the impacts of a hazard
63
What is the hazard risk equation?
Risk (R) = Hazard (H) x Vulnerability (V)
64
What is resilience?
Resilience is the ability or capacity of a community or society to withstand the effects of a natural hazard through methods of adaptation and recovery
65
Give 3 examples of an adaptation towards a natural hazard
1) Identifying the risks of a potential hazard
2) Planning what to do before a hazard occurs
3) Implementing plans to reduce impact
66
Give 2 examples of recovery towards a natural hazard
1) Stockpiling essentials (food, water, medicines)
2) Gathering resources for repairing and rebuilding
67
Define the term vulnerability
The extent to which a community could be damaged or disrupted by a hazard
68
What are 5 factors that impact a countries vulnerability?
1) The location of settlements
2) People's knowledge and understanding
3) People's ability to prepare, react to and withstand the effects of a hazard
4) The presence of advance warning systems
5) The involvement of local people in planning and preparation
69
What is the point of the Pressure and Release (PAR) model?
The PAR model is a way of summarising the links between natural hazards, risks and vulnerability
70
In the PAR model, what are the 3 sections that contribute to vulnerability?
Causes, pressures, living conditions
71
In the PAR model, what are the 2 sections that contribute to hazard?
Geography and Tectonics
72
Give 2 examples of causes that would contribute to vulnerability (PAR model)
Poor governance or poor economic systems
73
Give 2 examples of dynamic pressures that would contribute to vulnerability (PAR model)
Lack of education and skills, rapid population growth
74
Give 2 examples of unsafe conditions that would contribute to vulnerability (PAR model)
Weak buildings and infrastructure, insecure incomes and jobs
75
Give 2 examples of geography that would contribute to hazard (PAR model)
Magnitude, onset speed of hazard
76
Give 2 examples of tectonics that would contribute to hazard (PAR model)
Plate movements, earthquakes
77
Why do social and economic impacts of a hazard vary across countries?
Due to the level of development in that country
78
How can you measure economic development?
GDP per capita
79
How can you measure social development?
Considering levels of education/healthcare
80
How can you measure economic and social development?
Combined in the Human Development Index (HDI)
81
What does political development indicate?
Indicates the involvement of people in decision making
82
What does environmental development indicate?
Indicates a respect for and maintenance of natural systems
83
Name 5 ways to measure a tectonic hazard
1) Moment magnitude scale (Earthquakes
2) Mercalli intensity scale (Earthquakes)
3) Richter scale (Earthquakes)
4) Volcanic explosivity index (Volcano)
5) Tsunami intensity scale (Tsunami)
84
What is the moment magnitude scale?
A logarithmic scale used to measure the magnitude of earthquakes, where each level has 10 times the energy of the level below it
85
What is the mercalli intensity scale?
A scale that measures how intense the damage of an earthquake is
86
What is the volcanic explosivity index?
The VEI scale is a logarithmic scale to measure the greatness of an eruption, where each level has 100 times the energy of the level below it
87
What is the tsunami intensity scale?
The tsunami intensity scale that measures the damage of a tsunami. It is a logarithmic scale where each level has twice the energy of the level below it
88
What is the Moment magnitude scale scaled in?
3.0, 5.0 etc
89
What is the Mercalli intensity scale scaled in?
IV, VII, X, XII etc
90
What is the Volcanic explositivity index (VEI) scaled in?
1, 3, 5, 7 etc
91
What is the Tsunami intensity scale scaled in?
III, IV, V, VI etc
92
What is the purpose of a tectonic hazard profile?
They can be used to compare the characteristics and impacts of tectonic hazards
93
List 6 characteristics of a tectonic hazard
1) Spatial predictability
2) Areal extent
3) Frequency
4) Magnitude
5) Speed of onset
6) Duration
94
What is spatial predictability?
An estimation of what will occur where, and perhaps when
E.g., an area that has never had an event will experience greater impacts as people/places will be unprepared
95
What is areal extent?
The area that the hazard has affected
96
What is frequency?
How often an event occurs
97
What is magnitude?
The energy released (strength) of a hazard
98
What is speed of onset?
How quickly the event occurs
99
What is duration?
How long the event lasts
100
Are deaths caused by a hazard likely to be higher or lower in a HIC, and why?
Deaths in a HIC are likely to be lower, as in LIC's people lack awareness of hazards and they live in buildings that have not been proofed
101
Are damage costs caused by a hazard likely to be higher or lower in a HIC, and why?
Damage costs are likely to be higher in a HIC, as there are more expensive buildings/infrastructure to be repaired
102
Hazard profiles show ........... in ...... and ........ impacts between countries at different ...... .. ...........
Hazard profiles show differences in social and economic impacts between countries at different stages of development
103
List 8 influences on vulnerability/resilience
1) Unequal access to education
2) Unequal access to housing
3) Unequal access to healthcare
4) Unequal access to income opportunities
5) Urbanisation
6) Population density
7) Governance
8) Accessibility
104
How does unequal access to education influence vulnerability?
Some people lack formal education, so do not know about tectonic processes and hazards/what actions to take
105
How does unequal access to housing influence vulnerability?
Some people are poor and lack resources, so they do not live in strong buildings that can withstand hazards
106
How does unequal access to health care influence vulnerability?
Poorer people may lack access to doctors and medicine. During a hazard people need medical care for injuries
107
How does unequal access to income opportunities influence vulnerability?
Those with informal wages may struggle to save for safety improvements, insurance or stockpiling emergency resources
108
How does urbanisation influence vulnerability?
Urban areas are growing, which increases risk where buildings are not aseismic
109
How does population density influence vulnerability?
The denser the population, the larger the number of people that can be affected by a tectonic hazard
110
How does governance influence vulnerability?
Corrupted governments may prevent investment in hazard mitigation and adaptations
111
How does accessibility influence vulnerability?
Some countries or regions are isolated, by distance or physical barriers (mountains, sea etc). This means aid can be difficult to deliver
112
List 8 reasons for trends in tectonic hazards
1) Population increase - more people affected
2) High urbanisation rates - more people in a small area
3) More expensive construction/belongings - increases cost of damage
4) Widespread poverty - people living in risky areas in unfit housing
5) Inequality - Increased risk for those lacking access to information and services
6) Climate change - increasing the severity of weather
7) Environmental degredation - reducing protection from natural systems
8) More reporting - information through media
113
What 4 factors will make a disaster a mega-disaster?
-Over 2000 deaths
-Over 200,000 people made homeless
-Losses of 5% of national GDP or higher
-Dependence on external aid for one year or longer
114
What made the Haiti earthquake a mega-disaster?
-Killed up to 300,000 people
-Needed aid for over a year
-Cost 100% of GDP
115
What made the Kashmir earthquake a mega-disaster?
-Left over 3 million people homeless
116
How is global energy policies a global issue following a tectonic mega-disaster?
-Nuclear power stations can be damaged by seismic waves/tsunamis, releasing radioactivity
-Governments have become greatly concerned about this and have changed their attitudes towards their energy mix
117
How is global and regional economic activities a global issue following a tectonic mega-disaster?
-Volcanic ash may disrupt aircraft movements over a large area
-This costs airlines money in lost trade and compensation
118
How is global pollution a global issue following a tectonic mega-disaster?
Damaged/destroyed buildings, factories and power stations emit chemicals into the atmosphere, increasing ozone depletion and global warming
119
How is multi-national loss of life a global issue following a tectonic mega-disaster?
Due to international tourism/business, foreigners who find themselves in disaster events can cause grief across more than one country
120
How is global temps and regional food supplies a global issue following a tectonic mega-disaster?
Large volcanic eruptions send ash and SO2 into the atmosphere, which are carried around the world
These block and reflect the sun's heat energy, causing global warming
121
What 5 categories can multiple-hazard zones be grouped into?
-Meteorological
-Hydrological
-Geophysical
-Climatological
-Biological
122
Give an example of a meteorological hazard
Strong winds in a storm
123
Give an example of a hydrological hazard
River floods
124
Give an example of a geophysical hazard
Tectonic and mass movements
125
Give an example of a climatological hazard
Long-term drought
126
Give an example of a biological hazard
A disease, like cholera
127
Identify two deadly combinations of natural hazards where a tectonic hazard may be made worse
Volcanic eruptions with a tropical cyclone = lahars
Earthquakes and an outbreak of disease = no clean water to drink and no medicine
128
How could you predict/forecast an earthquake?
-Foreshocks
-Seismic monitoring and communications
-Absence of earthquakes
-Animals and birds
129
How could you predict/forecast a volcanic eruption?
-Geological evidence of past eruptions provides clues about the type and extent of future eruptions
-Measurements (gas emissions, harmonic tremors, bulging of volcano flanks, composition of magma)
130
How could you predict/forecast a tsunami?
-Warning systems
-Computer modelling
131
What are the 3 sections in the Hazard management cycle?
Pre-disaster, response, post-disaster
132
At what stage in the hazard management cycle is media focus the highest?
During the response
133
Define mitigation
Actions and interventions to reduce vulnerability before a natural hazard
134
Define preparedness
Ways in which communities can adapt to live with a natural hazard
135
Define resilience
Ability to resist, cope with, adapt to and recover from a natural hazard
136
Define response
Actions taken during and after a natural hazard to reduce impacts
137
Define recovery
Rehabilitation and reconstruction through restoring infrastructure, temporary housing, relocation and new risk assessment
138
Which tectonic hazard is easiest to modify, and why?
Volcanoes
Hazard zoning maps forecast where the biggest dangers are, and land-use zoning stops people living there
If nobody lives in the radius of danger then the impacts are modified
139
How can you modify an earthquake?
Not living near plate boundaries or fault lines, and building aseismic buildings
140
How can a volcanic eruption be modified?
Hazard zoning maps to forecast the biggest dangers, land-use zoning to stop people living there, draining crater lakes to reduce lahars, diverting lava flows
141
How can a tsunami be modified?
Tsunamis can be modified by building offshore barriers, higher and stronger walls, using mangrove forests
142
Define mitigation
Involves actions and interventions by a community that will reduce the severity of a hazard
143
List 7 ways to modify vulnerability and resilience
1) Hazard risk mapping
2) Land-use zoning
3) Food supplies
4) Monitoring and warning systems
5) Hazard resistance design
6) Investment in services
7) Improved evacuation routes
144
How can hazard risk mapping be used to modify vulnerability/resilience?
Modelling of hazard zones within an area, e.g. liquefaction areas or lahar routes
145
How can land-use zoning be used to modify vulnerability/resilience?
Strict planning regulations to stop building in risky, hazard prone areas
146
How can food supplies be used to modify vulnerability/resilience?
Increasing food production with better storage methods in case of emergency
147
How can monitoring and warning systems be used to modify vulnerability/resilience?
Gives people enough time to evacuate
148
How can hazard resistant design be used to modify vulnerability/resilience?
Any construction to be built to a specification strong enough to withstand impacts
149
How can investment in services be used to modify vulnerability/resilience?
Health-care systems can be better prepared, and education can raise the level of a community's understanding of hazards and actions to take
150
How can improved evacuation routes be used to modify vulnerability/resilience?
To enable people to escape in time
151
List 6 ways to modify loss
1) Rescue teams
2) Emergency relief aid
3) Community volunteers
4) Insurance
5) Evacuation
6) Development aid
152
How can rescue teams be used to modify loss?
Fully equipped with latest technology
153
How can emergency relief aid be used to modify loss?
Involving food, water, sanitation and shelter as well as medical care and medicines
154
How can community volunteers be used to modify loss?
Local people specifically trained for emergency events to guide and help other locals
155
How can insurance be used to modify loss?
Large or micro scale insurance to reduce financial losses for individuals and families, especially where livelihoods have been lost
156
How can evacuation be used to modify loss?
Move away from areas that may be hit again, including resettlement to safer locations
157
How can development aid be used to modify loss?
Long-term assistance from other countries to help rebuild what has been lost
