Tectonic Hazards: PG Flashcards
1
Q
What is Subduction?
A
The process by which the oceanic plate collides with a continental plate (or another oceanic plate), and the oceanic plate (or the older oceanic plate) descends below the continental plate.
2
Q
What is a Mantle Plume?
A
This is the process when a large column of hot rock rises from the earths core, through the mantle. The plume travels up until it reaches the lower lithosphere, causing the lithosphere to heat and melt, becoming vulnerable. This intense lava can push and stretch the lithosphere creating volcanoes on the surface of the upper lithosphere. This is how hotspots form.
3
Q
What is an INTRAplate?
A
When earthquakes form in the MIDDLE continents. (On the lithosphere)
4
Q
What is an INTERplate?
A
When earthquakes form on plate boundaries.
5
Q
What is Convection?
A
The movement caused within a fluid when the hotter (less dense) material rises then cools when further too far from heat source, causing it to sync. Hot=rise. Cold=sink.
6
Q
What is Seismic Activity?
A
This is vibrations in earth and its crust influenced by earthquakes.
7
Q
What is Slab Pull?
A
The PULLING FORCE (gravity) exerted on the oceanic plate plunging into the mantle, pulling the entire plate down due to its own weight.
8
Q
What are Island Arcs?
A
Long chains of oceanic islands with intense volcanic activity.
9
Q
What is the Benioff Zone?
A
The area beneath the Subducted plate where deep earthquakes occur as well as volcanic activity.
10
Q
What are Rift Valleys?
A
Formed when Continental plates move away from one another, magma rises in between, weakening the surface creating valleys as land lowers and falls. These valleys are filled with the eroded material from the ranges and volcanoes form in the centre where magma continues to rise.
11
Q
What are Mid Ocean Ridges?
A
Underwater mountain ranges that form when tectonic plates separate and magma rises then cools after magma piles up whilst still being produced before cooling, it creates mid ocean ridges.
12
Q
What are Deep Ocean Trenches?
A
Deepest parts of the ocean formed in subduction zones as tectonic plates collide. Form on the sea floor. (Long narrow spots in earths floor)
13
Q
What are Fold mountains?
A
When tectonic plates are pushed together forming hills, mountains and mountain ranges.
14
Q
What is Slab Push?
A
Plates are pushed away from each other as magma rises forcing older denser rock outwards and the new less dense rock replaces it. The process of the older rock being pushed away is ridge push.
15
Q
What is Sea Floor Spreading?
A
Underwater,as two continental plates are being pulled apart, magma is rising through the centre, filling the empty gap. When this magma cools and hardens it creates new land masses of oceanic crust.
16
Q
THREE facts about the global distribution of hotspots.
A
- Mainly located on oceanic plates.
- Sporadic in group
- Occur globally on continents.
17
Q
What patterns of ages do you see within the Hawaiian islands?
A
Age decreases as you travel East to South.
18
Q
How are the shapes of Hawaiian Islands formed?
A
They are influenced by oceanic erosion and its relationship with the sea.
19
Q
How do Hawaiian Islands Form?
A
Due to Hawaii being located on top of a hot spot, magma plumes form through concentrated towers of convection activity. The tectonic plates move whilst the magma plume remains stationary, forming new islands above the surface.
20
Q
What are Archipelagos.
A
Chains of islands.
21
Q
What volcanos are most common in Hawaai?
A
Shield Volcanoes.
22
Q
Shield Volcano Qualities.
A
- Basaltic Lava
- Flat gradient
- Very low silica content
- Low gas content
- Not explosive
- Very High temp magma
- Calm, less violent eruptions
- Fluid lava, travels far.
23
Q
Composite Volcano Qualities.
A
- Made of layers of Ash and lava
- Sticky Andesitic lava
- Extremely explosive due to build up of pressure
- Steep sided
- Thicker magma does not travel far
24
Q
What criteria’s must be met to define an event as a disaster?
A
- 10 people killed
- 100 people effected
- Declaration of an emergency by government
25
Define Vulnerability.
The susceptibility of a community to impacts of a hazard event.
26
Define Natural Hazard.
A naturally occurring threat that has the potential to cause loss of life injury, property damage, socioeconomic disruption or environmental degradation.
27
What are some PHYSICAL factors which makes a place vulnerable to a natural hazard?
1. Near the equator
2. Located on the coast
3. Located near bodies of water
4. Topography
5. Materials of buildings
6. Area prone to extreme weather (hot or cold temps)
7. Inaccessible areas
28
What are some HUMAN factors that make a place vulnerable to natural hazard?
1. Development of a country
2. Warning systems
3. Organisation level of rescue team
4. Money availability
5. Health and emergency service
6. Public education of emergency systems
29
Define Hazard Resilience.
The ability of a community which is exposed to hazards able to resist, absorb and recover from the effects of it timely and in an efficient manner.
30
Vulnerability to a Hazard equation.
Risk= Hazard X Vulnerability / Capacity to cope
31
Define Community Adaptions.
The ability for communities to prioritise, needs, knowledge and capacities after a hazard which help people better cope with and plan for impacts or natural hazards.
32
Define Mitigation
Actions prior to the event that reduce its impact.
33
What is a Richter Scale?
Measures the intensity of an earthquake from magnitude.
34
What is The Modified Meracalli Intensity Scale?
Measures intensity of an earthquake in terms of the amount of shaking due to the surface of which it is made of and the impacts it has on humans.
35
What is the Moment of Magnitude Scale?
Used by Seismologists to measure the size of the earthquakes in terms of energy released. Calculated from:
1. Amount of slip
2. Area affected
3. An earth rigidity factor
36
What is the Volcanic Explosivity Index?
A scale that allows explosive volcanic eruptions to be compared with one another. Measures both recent eruptions and Historical. Determined by assessing:
1. Volume/intensity of pyroclastic material ejected by the volcano.
2. Height of the eruption/plume
3. Duration of the eruption
37
What is the Tsunami Intensity scale?
New tsunami intensity scale, consistent within 12- grade seismic intensity scales. Arranged according to the effects on humans, nature and objects.
38
What are TWO limitations of the Richter scale?
1. The Richter Scale was originally devised to measure the magnitude of earthquakes of moderate size that is for magnitude 3 to 7 so can be less accurate for earthquakes outside this range.
2. The scale does not reflect the impact of vertical movement, which can be most damaging.
39
Advantages of Hazard Profiles on governments.
- Implement land use zoning to keep danger areas clear.
- Educating local people about what to do in a disaster
- Ensuring community preparedness
- Management strategies to manage loss
40
Difficulties with Hazard Profiles.
- Difficult to compare different hazards due to different measurement scales used.
- Impacts of earthquakes, volcanic eruptions and tsunamis vary.
- Difficult to rank multiple hazards on just one scale.
41
Why do people in lower income countries and emerging countries have higher vulnerability?
Basic health and nutritional status correlates with their ability to live, nutrition also effects people’s ability to fight disease. There is also a higher income of HIV/AIDs leading to more deaths and demand for healthcare which vulnerable countries cannot afford.
42
What are traits in Developed countries?
1. High population yet low birth rates.
2. Economical income is high therefore wealthy people.
3. Safe environment and secure livelihoods.
4. High technology.
5. Independence.
43
What are traits in emerging countries?
1. High populations and high birth rates.
2. Poor economy and poor people.
3. Unsafe environment and fragile livelihoods.
4. Low technology.
5. Dependance.
44
What are The Three P’s
The collective term for Prediction, Preparation and Protection
45
Define Protection
Constructing buildings so that they are safe to live in and will not collapse.
46
Define Preparation.
Attempt to reduce the damage likely to be caused by organising drills so that people know what to do in the event of an earthquake and to have emergency services available.
47
Define prediction.
Attempts to forecast an earthquake where and when it will happen based on current knowledge.
48
What are Three Protocols that take place in the Pre-disaster stage?
1. Risk Assessment
2. Migration/prevention
3. Preparedness
49
What Four Protocols take place in the Response Stage?
1. Warning/evacuation
2. Saving people
3. Providing Immediate assistance
4. Assessing Damage
50
What Five Protocols take place in the Post-disaster Stage?
1. Restoration of infrastructure services
2. Reconstruction
3. Economic and social recovery
4. Ongoing development activities
5. Risk assessment mitigation/prevention
51
Define Mitigation.
Preventing hazards from becoming disaster or minimising their effect.
52
Define Preparedness.
The state of being ready for a hazard event.
53
Define Response.
How quickly a country acts post hazard event.
54
Define Recovery.
Getting back to normal.
55
In the Hazard Management Cycle, how does Mitigation play a role?
Identifying potential hazards and taking steps to reduce their impacts. Main aim to reduce loss of life and property.
56
Actions involving Mitigation.
1. Zoning and land use planning
2. Developing and enforcing building codes and building protective structures ( eg tsunami defensive walls ).
57
In the Hazard Management Cycle, how did Preparedness play a role?
Facilitating the response and recovery phases. Many activities are developed and implemented by emergency planners in both government and aid organisations.
58
What were the Actions involving Preparedness?
1. Developing preparedness plans
2. Developing early warning systems
3. Evacuation routes
4. Stockpiling aid and equipment
5. Raising public awareness e.g earthquake drills
59
In the Hazard Management Cycle, how did Response play a role?
Short term recovery- focus on people’s immediate needs > last for weeks.
Long term recovery- focus on people’s long term needs > last for months or years
60
What are the actions involving Response?
Short term:
- health services
- restore power supplies
- discover transportation routes
- temporary shelter
Long term:
- rebuilding homes
- rebuilding infrastructure
- re-opening businesses
61
In the Hazard Management Cycle, how did Recovery play a role?
Coping with disasters. Main aim to save lives and protect property. Make effected areas safe & reduce economic cost.
62
What are the actions involving Recovery ?
1. Search and rescue efforts
2. Rehabilitation
3. Restoring infrastructure
4. Ensuring emergency services continue
63
What is the Hazard Management Cycle?
The process by which the government and other organisations work together to protect people from natural hazards that threaten their communities.
64
Define each stage of The Parks Model.
Stage 1: Occurs prior to the event and shows the quality of life is at its normal equilibrium level.
Stage 2: Where the hazard occurs but the quality of life is still normal.
Stage 3: Event has happened and search for rescue is underway. Quality of life drops and stays low for hours/days/months depending on the development of the region and the severity of hazard.
Stage 4: Relief strategies are underway, organising program for help, can take hours/days/weeks/months but quality of life is improving.
Stage 5: Reflects on the nature of the recovery and strategies to modify vulnerability.
65
Explain the value of Parks hazard-response curve in understanding the management of the impacts of tectonic hazards. ( 4 marks )
> Helps organisations understand what stages are after and before an event and which ones are most significant to preventing further vulnerability.
> How each stage supports the other and the comparison of stages between different hazard events.
66
What are features of The Parks Model?
> Depth of curve indicates the quality of life immediately after hazard.
> Wealthier countries have very different curves to LIC or NIC countries as they will recover faster.
> If a hazard effects more then one country, each country will have its own curve.
67
How to you modify a Tsunami event and the human vulnerability?
> Modify by Coastal defence & engineering.
> Modify human vulnerability by warning & prediction, coastal zones management and provision of emergency kits.
68
How do you modify Earthquakes and human vulnerability?
> Not possible to modify event.
> Modify human vulnerability by implementing a seismic buildings & education drills.
69
How do you modify Volcanoes and human vulnerability?
>Modify event by lava diversion.
> Modify human vulnerability by doing monitoring, prediction, warning, evacuation systems, hazard mapping, education and shelter.
70
What is Land Use Zoning?
Process by which local government planners regulate how land in a community may be used. (E.g. residential or industrial). Land use zoning is common in wealthy countries but less common in developing countries.
71
What processes does a region undergo in Land Use zoning?
1. Settlements are limited
2. Structures will be prohibited
72
What are Diverting lava flows?
This is when lava flows are diverted away from people & properties. This includes building barriers & digging channels to try to divert the flows into safer directions.
73
What are some Disadvantages of Diverting lava flows?
1. By stopping the lava from flowing towards one community may push it towards another.
2. The type of land (terrain) must be suitable (e.g. downward slope)
74
What is GIS mapping?
Used to identify where evacuation routes should be placed (prepare) or help rescues & recovery’s. Combines information about location,population, areas affected by earthquake & locations of airports
75
Distribution of EARTHQUAKES.
- 70% of earthquakes are found in the Pacific Ring of fire.
- Most powerful earthquakes are found at…
CONVERGENT plate boundaries
CONSERVATIVE plate boundaries
INTRA PLATES
76
Distribution of Volcanoes.
- 500 active volcanos world wide.
- Around 50 erupt each year.
- Occur mostly on plate boundaries, some occur on hot spots.
77
How is the violence of an eruption determined?
Determined by the amount of gas in the magma and how easily it can escape.
78
Distribution of Tsunamis.
- Movement can be caused by earthquakes, volcanic eruptions or underwater landslides.
- Occur close to plate boundaries.
79
What are Oceanic Fracture Zones?
Belt of activity through mid ocean ridges.
80
What are Continental Fracture Zones?
Belt of activity following mountain ranges.
81
Structure of the Earth.
1. Inner Core> Solid, mostly Iron.
2. Outer Core> Semi molten, mostly iron & nickel.
3. Mantle> Semi molten upper part, Solid lower part.
4. Crust> Solid Oceanic & Continental.
82
What is the Oceanic Crust?
-Basalt
-Thin
-Very Dense
- Makes up seafloor (underlies ocean basin)
83
What is the Continental Crust?
-Granite
-Thick
-Very dense
-Makes up the continents (underlies continents)
84
What is Pangea?
A supercontinent which incorporated almost all of earths land masses in early geological time.
85
What is Paleomagnitism?
- The study of past changes in earths magnetic field
- The poles switch up every 200,000 years
-When magma cools, magnetic materials inside the rock line up with the Earth's magnetic direction
86
Evidence for Sea floor spreading.
1. The cooled rock in between two plates in basalt, a younger rock. It is evident that this rock has been produced more recently than the rocks surrounding it.
2. Temperatures around mid ocean ridges are warmer, showing that they were produced through magma cooling.
87
What is Acid rain?
When volcanos erupt they release sulphur dioxide into the atmosphere. This reacts with air to form acid rain.
88
What are Lava Flows?
Streams of lava that have erupted onto earths surface.
89
What are Pyroclastic flows?
Mixture of hot dense rock,lava,ash and gases move quickly along the surface of the earth.
90
What is Tephra & Ash flows?
When volcanic rock fragments and ash are ejected from the volcano into the atmosphere.
91
What are volcanic gases?
Gases such as sulphur dioxide and carbon dioxide are released into the atmosphere when a volcano erupts.
92
What are Jokulhlaups?
The heat from the eruption melts snow and ice in glaciers which causes sudden floods.
93
What are Lahars?
Volcanic mudflows composed of rock, mud and water.
94
What are the risks of Pyroclastic flows?
- Their high speeds make them extremely dangerous.
- Can cause asphyxiation and destroy everything in their path.
95
What are the risks of lava flows?
- Fast flowing lava can be extremely dangerous.
- Flow up to 40km/h
96
What are the risks with Jokulhlaups?
Dangerous to people and infrastructure.
97
What are the risks with Acid rain?
Can harm ecosystems and erode away buildings.
98
What are the risks with volcanic gases?
- Can travel long distances so they can affect more places then just the source.
- Most deaths are associated with carbon dioxide as it is colourless and odourless.
- Can have an impact on the atmosphere and greenhouse effect.
99
What are the risks with Tephra and Ash flows?
- Can cause roofs to collapse and fires to start.
- Dust reduces visibility which may affect air travel.
- Can cause respiratory problems.
100
What are the risks with Lahars?
Travel quickly down the sides of volcanos.
101
What is a Landslide?
A type of mass movement which moves a mass of rock, debris or earth down a slope.
102
What are the Risks of Landslides?
- Earthquakes create stresses that make weak slopes fail.
- Earthquakes of a magnitude 4 and above have been known to trigger landslides.
103
What is Mass Movement?
Any down slope movement of soil/rock under the direct influence of gravity.
104
TWO facts about Earthquakes.
- On average 10,000 people die each year due to earthquakes.
- Earthquakes occur in the crust or upper mantle, ranging from the earths surface to about 800 kilometres deep.
105
What are the 4 TYPES of earthquakes?
1. Divergent- weak & shallow.
2. Convergent Destructive- most powerful & deepest.
3. Convergent Collision - powerful & deep.
4. Conservative - powerful & deep.
106
What are Earthquakes?
Sudden vibrations in the earths crust caused by a release in a build up of energy between tectonic plates.
107
What are Tsunamis?
A large ocean wave caused by a sudden movement on the ocean floor. (usually from earthquakes, volcanic eruptions or underwater landslides)
108
What are the characteristics of Tsunamis?
- Wave height= 1m
- Wave lengths= 100km
- Wave speeds = 500-950km/h
109
What is Soil Liquefaction?
Where water saturated material can temporarily lose strength an d behave like a liquid under the pressure of intense shaking.
110
What are the Impacts of Soil Liquefaction?
- Damage to roads and bridges
- Telecommunications effected
- Delivery of aid
- Costs to rebuild affected areas can be substantial
111
What is Seismology?
The study of earthquakes and seismic waves.
112
Define the FOUR types of Seismic Waves.
1. Primary Waves: travel through solids, vibrate in direction of travel, cause the least amount of damage.
2. Secondary Waves: travel through solids, vibrate at right angles to direction of travel, don’t cause a lot of destruction.
3. Love Waves: vertical ground movement, near ground surface, most destructive.
4. Rayleigh Waves: Vertical and horizontal displacement, most destructive.
113
What is the difference between a Hazard and a Disaster?
A Hazard is when a naturally occurring event which has threatened life and property. The disaster is when the hazard has caused a significant impact on a population.
114
Define the FIVE types of Vulnerability.
1. PHYSICAL= a hazard prone area with little protection.
2. ECONOMIC= risk of loosing employment or wealth from a hazard.
3. KNOWLEDGE= lack of training or warning.
4. SOCIAL= communities unable to support most vulnerable.
5. ENVIRONMENTAL= high population density.
115
What SIX physical processes do all Hazards share and compare?
- Frequency
- Magnitude
- Duration
- Speed of onset
- Fatalities
- Economic loss
- Spatial predictability
116
What is a Conservative PB?
When two plates collide past each other as they travel in opposing directions.
117
What is a Collisional PB?
When two plates collide into one another when travelling in opposing directions, form mountain ranges as the land uplifts.
118
What is a Destructive PB?
When two plates collide into each other where the denser crust is forced beneath the other through the process of subduction.
119
What is a Constructive PB?
When two plates move away from each other, whilst magma rises from thee mantle. As the plates move apart eruptions and earthquakes form.
120
What are Properties of Andesitic lava?
1. Viscous
2. High silica content
3. Form Composite volcanoes (steep sided volcanoes)
4. Thick & sticky
121
What are properties of Basaltic lava?
1. Runny and fluid
2. Not explosive
3. Shield volcanoes (gentle sided)
4. Low silica content
5. Not viscous
122
Properties of Oceanic plates.
1. Thin crust
2. Young and constantly producing
3. Higher density.
123
Properties of Continental Plates.
1. Thick crust
2. Forms large land masses
3. Older then oceanic
4. Lower density
124
What is a Lithosphere?
The surface layer of earth which is rigid/strong and composed of upper mantle and crust. It travels slowly
125
What is an Asthenosphere?
The deeper layer of earth which is weak and made up of mantle. It is hot and easy to deform as it is the flowing part of the upper mantle.
126
What are TWO theories of Plate tectonics?
1. Supercontinent: the idea that 300 million years ago all the continents existed as one supercontinent.
2. Pangea: the theory of continental drift suggested that due to slab pull, subduction, mantle convection and sea floor spreading, this supercontinent separated into the continents we know
127
What are the FOUR types of Geological evidence for Historical plate tectonics?
1. Jigsaw fit coastlines> the idea that continents had once been joined as they puzzle together as the same rocks connect, which were previously broken up by erosion.
2. Geological fit> across continents the same type of geology aligned, suggesting lands where part of the same mass years ago.
3. The Mid Atlantic ridge> showed new rock being created, and evidence that the Atlantic floor was spreading outwards from the centre.
4. Glaciation> evidence for today’s glacial deposits.
128
What are TWO types of Climatic evidence for Historical Plate tectonics?
1. Tillite: boulder clay that has been turned into hard rock— deposits are forming beneath glacier sheets.
2. Carboniferous Period when the UK experienced hot tropical climates. Seas were warm, growth of coral was rapid, deposits of limestone.
129
What is ONE type of Biological evidence for Historical plate tectonics?
1. Fossil evidence; plant and animal fossils found on the coastlines of different continents (e.g. South America & Africa). The same organisms evolved on different continents.
130
What Hazards result because of Destructive plate boundaries?
- Tsunamis caused here.
- Largest earthquakes in the world.
- Andesitic Volcanoes.
131
What Hazards result because of Collisional plate boundaries?
- Earthquakes due to build up of pressure.
- No volcanic activity.
132
What hazards result from Conservative plate boundaries?
- Earthquakes of considerable magnitude & shallow focus.
- No volcanic activity.
133
What hazards result from Divergent plate boundaries?
- Earthquakes are frequent but small and low hazard.
- No Tsunamis.
- Rift volcanoes (less explosive)
134
What is the Focus?
Point INSIDE crust from which the pressure from the earthquake is released.
135
What is the Epicentre?
The point ONTOP of the surface, directly above the focus. This is where most damage occurs.
