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Tectonics Flashcards

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1
Q

What is a Seismic Hazard?

A
  • A hazard that affects rocks within 700km of the Earth’s surface
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2
Q

What is a Volcanic Hazard?

A
  • A hazard that involves eruption events
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3
Q

What is an Oceanic Fracture Zone?

A
  • A belt of activity through the oceans in Africa, Red Sea, Dead Sea and California
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4
Q

What is a Continental Fracture Zone?

A
  • A belt of activity following the mountain ranges in Spain and the Alps. It runs across to the Middle East, the Himalayas and East Indies.
  • it cuts off in the Philippines
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5
Q

What are Ancient Fault Lines?

A
  • Old tectonic fault lines that are constantly under stress but hardly tremor
  • E.g -> Stretton Fault Line in South Shropshire UK
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6
Q

What is the Hotspot Theory?

A
  • High heat and lower pressure at base of Lithosphere allow rocks to melt
  • Magma rises though cracks + erupts to form active volcanos
  • As plate continues to move over plume, land passes over hotspot + another volcano forms
  • Creates volcanic island chains like Hawaii
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7
Q

What is a Volcanic Hotspot?

A
  • An area in the mantle from which heat rises as a thermal plume from deep on the Earth
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8
Q

What are the three important theories linked to convection currents?

A
  • Continental drift
  • Sea floor spreading
  • Palaeomagnetism
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9
Q

What evidence is there for the Continental Drift Theory?

A
  • Continental Fit -> Visible that countries slot together
  • Geological evidence, rocks of the same age and type found where countries would have fit together
  • Similar fossil formations found in separated areas
  • Climatological evidence, places that are no longer tropical, have evidence of once being tropical
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10
Q

What evidence is there for the Sea Floor Spreading Theory?

A
  • Harry Hammond -> Dive in the ocean and found mid-ocean ridges, above sea level
  • Sea floor at the ridges was younger than to the side
  • Rock near the ridges formed by the spreading of the rock
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11
Q

What evidence is there for the Palaeomagnetism Theory?

A
  • Vine and Matthews -> Very young rock at places on or near ocean ridges
  • Magnetic domains within iron-rich minerals in lava are aligned with the magnetic field of the Earth -> Means they can record polarity of the earth
  • Shows the polarity changes every 400,000 years -> Poles switch
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12
Q

Wha are Benoiff Zones?

A
  • Path of a subducting plate
  • Angle of subduction tells us where earthquakes may occur
  • Different speeds + movement of rock at this point produce numerous earthquakes
  • Medium + deep focused earthquakes
  • Important in determining earthquake magnitude
  • Determines position and depth of hypo centre
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13
Q

What are Locked Faults?

A
  • Significant tectonic hazards
  • Usually found at leading edge of subduction zone
  • Stuck due to frictional resistance being greater that the sheer stress
  • can store strain for extended periods -> Eventually released in large magnitude earthquakes
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14
Q

What is the Slab Pull Theory?

A
  • Plates are ‘pulling’ themselves along
  • Thinner plate subjects and pulls on plate behind it
  • Magma in the mantle helps to pull the slabs due to convection currents
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15
Q

What is a Divergent (Constructive) plate margin?

A
  • Two plates moving apart, forms new crust
  • Forms mid-ocean ridges in the ocean and on continents forms riff valleys
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16
Q

What is a Convergent (Destructive) Subduction plate boundary?

A
  • Oceanic plate is denser than continental plate
  • Oceanic plate slides beneath continental plate into mantle
  • Crates deep ocean trenches and forms fold mountains
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17
Q

What is a Convergent (Destructive) Collision plate boundary?

A
  • Two continental plates meet
  • Plates are less dense than asthenosphere which means no subduction occurs
  • Particles crumple and form fold mountains -> Like Himalayas
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18
Q

What is a Conservative/ Transform plate boundary?

A
  • Two plates slide past each other forming a conservative margin
  • Breaks the crust
  • Called a fault
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19
Q

What are the 4 types of Seismic Waves?

A
  • Primary
  • Secondary
  • Rayleigh
  • Love
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20
Q

What are Primary Waves?

A
  • Seismic waves that occur immediately during an earthquake
  • They are a bodywave
  • Travel through liquids and solids
  • Push and pull the earth in the same direction as the waves
  • Fastest waves
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21
Q

What are Secondary Waves?

A
  • Seismic waves that occur immediately after an earthquake has happened
  • Are a bodywave
  • Only travel through solid -> Not the core
  • Move body + surface from side to side
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22
Q

What are Rayleigh Waves?

A
  • Surface wave
  • Travel through solids + liquids
  • Move surface in a rolling motion
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23
Q

What are Love Waves?

A
  • Surface wave
  • Travel through solid but not liquid
  • Move through surface
  • Move 10 Degrees side to side
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24
Q

What are causes and impacts of earthquakes?
- Is it a primary or secondary hazard?
- Case Study?

A
  • Primary Hazard
  • 95% occur along plate boundaries -> When they rub together and build up pressure
  • Pressure is released at focus/ hypo centre -> Most damage occurs at epicentre on surface
  • 10,000 people die every year as a result
  • Case study = Haiti 2010
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25
Q

What are causes and impacts of Landslides + Avalanches?
- Are they Primary or Secondary?
- Case Study?

A
  • Secondary Hazard
  • Ground shaking destabilises cliffs + Steep slopes -> Causes landslides, rockslides, mudslides and avalanches
  • More likely as a result of heavy rain + unconsolidated or fractured rocks
  • Many effects account for damage caused by earthquake
  • Case Study = Christchurch 2010, Nepal
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26
Q

What are causes and impacts of Tsunamis?
- Are they Primary or Secondary?

A
  • Secondary Hazard
  • Generated by an earthquake under the ocean -> When large amounts of water is displaced by moving of tectonic plates
  • Can move with speed
  • Wall of water that can sweep miles inland destroying everything in their path
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27
Q

What are causes and impacts of Fire?
- Are they Primary or Secondary?

A
  • Secondary
  • Caused by fractured gas mains following and earthquake in built up areas
  • Water mains may also be fractured making fire hard to extinguish
  • Spread quicker in LIC’s where properties are built with wood
28
Q

What are causes and impacts of communications + infrastructure destroyed?
- Are they Primary or Secondary?

A
  • Secondary Hazards
  • Road + Rail links often damaged to destroyed
  • Telephone masts + wifi down = hard to call for help + find loved ones
  • Hampers rescue effort as well as causing injury + loss of life
29
Q

What are causes and impacts of Liquefaction?
- Are they Primary or Secondary?
- Case Study?

A
  • Secondary Hazard
  • Violent shaking of ground can cause surface rock to lose strength + become more liquid than solid
  • Marshy or saturated land can lose its strength and act like liquid
  • Soils underneath building foundations causes them to fail and sink
  • Case Study = Christchurch 2010
30
Q

What are causes and impacts of Aftershocks?
- Are they Primary or Secondary?
- Case Study?

A
  • Secondary Hazard
  • Smaller but significant earthquakes after main earthquake
    Can continue in following weeks + months of an earthquake
  • Rescue workers at risk of collapsing buildings
  • Larger the earthquake, the more aftershocks there are
  • Case Study = Christchurch 2010
31
Q

What are causes and impacts of Quake Lakes?
- Are they primary or Secondary?

A
  • Secondary Hazard
  • Earthquakes trigger landslides which can block rivers + cause flooding
  • Water collects, creating ‘quake lakes’ + flooding huge areas
  • Aftershocks can collapse dams sending a torrent downstream
32
Q

What are causes and impacts of Disease?
- Are they Primary or Secondary?

A
  • Secondary Hazard
  • Lack of water + sanitary = diseases such as cholera + dysentery to spread quickly
  • Dead bodies buried in rubble + unregulated mass graves spread disease and cause pollution
33
Q

What is basaltic lava?

A
  • Lava that is low in silica and therefore tends to be very fluid
34
Q

What is andesitic lava?

A
  • Silica-rich (Acid) magma which is often viscous.
  • Often solidifies before reaching the surface, causing pressure which leads to explosive activity
35
Q

What is the Volcanic Explosively Index?

A
  • Relative measure of explosiveness of volcanic eruptions
  • Volume of products, eruption cloud height + qualitative observations to determine explosivity value
  • Scale = open ended with targets volcanoes in history being given Magnitude 8
  • Logarithmic scale
36
Q

What are the 4 volcanic hazards?

A
  • Volcanic gasses
  • Tephra
  • Pyroclastic flows
  • Lava flows
37
Q

What are Volcanic gasses?

A
  • Gasses associated with explosive eruptions and lava flows
  • Mix normally includes water vapour, Sulphur dioxide, Hydrogen and Carbon monoxide
  • Dangerous as carbon monoxide is colourless and odourless -> Carbon Monoxide usually the biggest cause of death
38
Q

What is Tephra?

A
  • Material such as rock fragments that are ejected into the atmosphere as a result of a volcanic eruption
  • Can vary in size from ‘bombs’ to ‘fine dust’
  • Ash and large materials can cause building roofs to collapse as well as start fires on the ground
39
Q

What are Pyroclastic Flows?

A
  • Responsible for most volcanic related deaths
  • Result of frothing of molten magma in the vent of the volcano
  • hot gasses and pyroclastic materials, which contain glass shards, pumice, crystals and ash, are ejected from the side of the volcano
  • Clouds can be up to 1000 degrees Celsius
  • Can travel extremely quickly
40
Q

What are Lava Flows?

A
  • Lava that erupts out of a volcano
  • Viscosity determined by amount of silicon dioxide it contains
  • Can take up to a day to cool and is very slow moving
41
Q

what 5 ways are there to classify volcanoes?

A
  • If they are active
  • By their characteristics (The Landform)
  • VEI - Volcanic Eruption Index
  • Type of eruption
  • Type of magma
42
Q

How can you classify volcanoes by their activity?

A
  • Active volcano still erupts
  • Dormant volcano is not erupting but is supposed to erupt again
  • Extinct volcano has not erupted for at least 10,000 years
43
Q

How can you classify volcanoes by their characteristics?

A
  • By what the volcano physically looks like:
  • Shield Volcano = Wide and Gentle slopes (Divergent plate boundary)

Composite Volcano = Steep sloping sides, with layered composition and typically a lot more violent

44
Q

How can you classify volcanoes by the VEI?

A
  • Using several volcanic characteristic to judge the size or an eruption:
  • Eruption cloud height
  • Volume of products erupted
  • More subjective qualitative observations
45
Q

How can you classify volcanoes by the type of eruption?

A
  • Based upon their explosivity, and their names are generally derived from volcanoes which chow characteristics of those eruptions
  • E.g Hawaiian Eruptions = Lava is more basic and basaltic, with low gas pressures and low silica content
46
Q

How can you classify volcanoes by the type of magma?

A
  • Characteristics of molten rock give different eruption types
  • There are 3 main types of lava
  • Lava can be basic or acidic:
  • Basaltic
  • Andesitic
  • Rhyolitic
47
Q

What are primary effects of volcanoes?

A
  • Tephra
  • Pyroclastic flows
  • Lava
  • Volcanic gasses
48
Q

What are secondary effects of volcanoes?

A
  • Lahars = Volcanic mudflows
  • Flooding
  • Tsunamis
  • Volcanic landslides
  • Climatic change
  • Jokulhlaup = Glacial outburst floods
49
Q

What is the PAR model?

A
  • Pressure and Release model
  • Root Causes -> Dynamic Pressures -> Unsafe conditions -> Disaster <- natural Hazards
  • Shows progression of vulnerability and demonstrates how it is a snowball effect
50
Q

What is the PAR model?

A
  • Pressure and Release model
  • Root Causes -> Dynamic Pressures -> Unsafe conditions -> Disaster <- natural Hazards
  • Shows progression of vulnerability and demonstrates how it is a snowball effect
51
Q

What is the equation for disaster risk?

A

Hazard X Vulnerability
Disaster Risk = ——————————-
Capacity to Cope

  • Disaster risk = Hazard + Vulnerability
52
Q

What do root causes involve in the PAR model?

A

Limited access to:
- Power
- Structure
- Resources

Ideologies:
- Political Systems
- Economic Systems

53
Q

What do Dynamic Pressures involve in the PAR model?

A

Lack of:
- Appropriate skills
- Training
- Local Investment
- Press Freedom
- Ethical Standards in Public Life

Macro-forces:
- Rapid population Change
- Rapid Urbanisation
- Deforestation
- Arms Expenditure
- Debt Repayment Schedules

54
Q

What do unsafe Conditions involve in the PAR model?

A
  • Fragile Physical Environment
  • Fragile local economy
  • Vulnerable society
  • Public Actions
55
Q

what factors effect risk?

A
  • Education
  • Frequency
  • Geographical location
  • Level of Development
  • Magnitude
  • Natural factors
  • Population density and distribution
  • Time
56
Q

What are the 4 scales used to measure tectonic hazards?

A
  • Richter scale
  • Mercalli Scale
  • Moment Magnitude Scale (MMS)
  • Volcanic Explosivity Index (VEI)
57
Q

What is the Risk-Poverty Nexus?

A
  • Illustrates that differences in risk inequality is linked to many different elements

Has factors that are all interlinking:
- Extensive and intensive risks
- Disaster Loss
- Poverty Outcomes
- Everyday risks
- Multidimensional poverty

58
Q

What factors can lead to inequalities within a country?

A
  • Wealth
  • Political -> Access -> ability to vote/ represent
  • Social -> housing in vulnerable areas
    -> access to regular income -> living in hazard exposed areas
  • Asset -> housing + security of tenure -> Agricultural productivity + goods saving
  • Entitlements -> Access to public services + welfare systems -> Inequality in rule of law
59
Q

What is Forecast of a hazard?

A
  • The statistical likelihood of a event occurring
60
Q

What is Prediction of a hazard?

A
  • Knowing when, where and the magnitude of an event
61
Q

How are Earthquakes forecasted and predicted?

A
  • Forecast based on statistical likelihood -> based on seismic monitoring networks and historic records
  • Long term forecasts are more reliable than short term
  • Forecasting still important as encourages governments to enforce better building regulations or improved evacuation procedures
  • Not possible to make accurate predictions of Earthquakes
62
Q

How are Volcanoes forecasted and predicted?

A
  • Remote sensoring
  • Earthquake + Lahar sensors
  • Satellite
  • Thermal imaging
  • Cameras
  • Tilt meter
  • Ground vibration
  • Deformation
  • Gas -> airborne + ground
  • GPS
  • Surveying
63
Q

What is Mitigation?

Examples in Haiti and Christchurch

A
  • Identifying potential natural hazards and taking steps to reduce their impact.
  • The main aim is to reduce the loss of life and property

Haiti:
- Minimal -> No earthquake proof buildings

Christchurch:
- A lot of Aseismic buildings

64
Q

What is Preparedness?

Examples in Haiti and Christchurch

A
  • Minimising loss of life and property and facilitating the response and recovery phases
  • Many activities are developed and implemented by emergency planners in both governments and aid organisations

Haiti:
- Lack of preparation -> Emergency services didn’t know what to do

Christchurch:
- in an earthquake hotspot so would have done lots of drills

65
Q

What is Response?

Examples in Haiti and Christchurch

A
  • Coping with disaster
  • the main aims are to save lives, protect property, make the effected areas safe and reduce economic losses

Haiti:
- Spent money on disease rather than restoration

Christchurch:
- Enforced law
- Pop-up hospitals created
- Over 300 police flown in to help

66
Q

What is Recovery?

Examples in Haiti and Christchurch

A

Short-term:
- This focuses on people’s immediate needs, so it overlaps with the response phase
- Although called short-term these activities may last for weeks

Long-term:
- This involves some of the same actions but may continue for months or even years
- it includes taking steps to reduce future vulnerability, which overlaps with the mitigation and the cycle continues

Haiti:
- $13 Billion of aid donated
- Overseas companies managing restoration

Christchurch:
- Constructed of homes
- Earthquake proof (Aseismic) housing
- Water + Sewage restored

67
Q

What is the Parks Model?

and what are the 5 stages?

A
  • Shows how an area responds after a hazard
  • Can vary dues to size of hazard, predictability of hazard, vulnerability of area
  • Stage 1 = Modifying the cause and event
  • Stage 2 = Hazardous event
  • Stage 3 = Search, rescue and Care
  • Stage 4 = relief and rehabilitation period -> May include outside help (National or International)
  • Stage 5 = Nature of recovery related to:
    -> the need to reduce vulnerability
    -> the need to restore normality as soon as possible

Geography (6 decks)

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