Tectonic Hazards Flashcards
1
Q
Why do we have tectonic plates?
A
- Heat generated in the earth’s core by radioactive decay drives convection currents in the outer core and mantle
- These slowly tear the earth apart and are responsible for movement
2
Q
Name each layer of the earth down to the asthenosphere
A
- Continental crust
- Oceanic crust
- Upper most mantle
- Partially molten asthenosphere
3
Q
How deep is the lithosphere and what layers of the earth does it consist of?
A
- 100km deep
- Continental crust, oceanic crust and upper most mantle
4
Q
How deep is the asthenosphere?
A
100 km to 200 km deep
5
Q
Why do we have oceans and land?
A
Ocean plates are lower in altitude compared to continental plates, water will begin to fill the lower parts of the crust up first due to gravity
6
Q
What is the difference between oceanic and continental crust?
A
Oceanic
- thin, dense rock, 4 to 7 km in thickness
Continental
- thick, 6 to 47 miles in thickness, less dense rock
7
Q
Give characteristics of the lithosphere
A
Solid, 100 thick, consists of oceanic and continental crust and upper mantle
8
Q
Give characteristics of the asthenosphere
A
Thick (Viscous liquid) moving very slowly, tectonic plates move on top of it.
9
Q
Why do continental and oceanic plates differ in altitudes?
A
- Continental plates have more mass but are less dense meaning they will float on top of the asthenosphere
- Oceanic plates have less mass but are more dense meaning they will partially sink into the asthenosphere
10
Q
How old are oceanic and continental rock?
A
Oceanic - 400 million years old
Continental - 2 billion years old
11
Q
How is oceanic rock created and destroyed
A
Birth
- Magma from volcanic eruptions cools and solidifies to become rock
Death
- At a destructive plate margin, oceanic plate sub ducts into the asthenosphere and turns back to magma
12
Q
How is continental rock created and destroyed?
A
Birth
- Continental rock is oceanic rock that has survived long enough to become continental
Death
- Erosion - land has to pushed up to a high altitude e.g fold mountains at a collision plate boundary, meaning that it is exposed to erosion and eventually destroyed
13
Q
Give three of examples of oceanic plates and 3 examples of continental plates
A
Oceanic - Pacific plate, Nazca plate, Philippine plate
Continental - South American plate, African plate, Eurasian plate
14
Q
What three types of plates are there depending on size and give two examples of each
A
Major - African plate, Eurasian plate
Minor - Caribbean plate, Arabian plate
Micro - Too small to see on a world map
15
Q
Why are most of the major plates continental?
A
- Continental plates are harder to destroy as they have to pushed up at a collision plate boundary to then be eroded
- Oceanic plates are easier to be destroyed by subduction at a destructive boundary
16
Q
Give the the 6 pieces of evidence for continental drift
A
- Early ‘jigsaw’ ideas - all of the continents look like they once fit together, meaning we can assume they were all connected at one point
- Magnetic readings of seafloors- individual rock is very unique, like a fingerprint, in rocks there are substances like iron oxide that have a magnetic field strength, through periods of time magnets point range from north to south, at certain points we find identical rock that are far apart but mirror each other, suggesting that the plates are moving as the rock must have been created at the same time but was seperated, this is called paleo-magnetism.
- Coal and mineral locations - coal is compressed vegetation, e.g. coal has been found in Antarctica, where there is no vegetation, therefore suggesting that Antarctica must have moved further away from the equator over time.
- Dinosour fossils found across areas - fossils of the same species of dinosour were found across different continents, dinosour cannot swim, suggesting that all the continents were together at one point.
- Glaciated landscapes - found in tropical locations, suggesting the land has moved closer to the equator.
- Volcanic landscapes - volcanic land forms no where near any volcanoes, the land must have been near a volcano at one point but drifted away.
17
Q
Give the three factors that determine the speed of plate movement
A
- Convection currents - core emits heat to the asthenosphere and then the heat cools and falls down again to the core, this moves the liquid in the asthenosphere and therefore moves the plates above it
- Ridge push - when volcanoes erupt magma cools and solidifies to create a ridge, gravitational energy acts on the ridge to push it down which causes the plate to move faster.
- Slab pull - when a plate subducts it pulls down the rest of the plate due to gravity, speeding up the plates movement
18
Q
What characteristics of a boundary determine which geographical hazards will occur and their potential magnitude
A
Direction and type of plate (oceanic or continental)
19
Q
Describe a destructive plate boundary.
A
- Can be either a continental and oceanic plate or two oceanic plates.
- Plates move together due to convection currents, slab pull and ridge push.
- They form fold mountains due to buckling at collision points
- Cause earthquakes as stresses build up and are released.
- The denser one always subducts.
- Has a Benioff zone where the denser plate turns back to magma.
20
Q
What happens when two oceanic plates converge
A
the denser plate subducts, normally the younger plate
this creates underwater ocean trenches
21
Q
Describe a collision plate boundary
A
- Two continental plates converging
- no subduction as both plates are too dense
- shallow stresses because of no subduction
- buckle to create fold mountains
- e.g. indo- australian plate converging with the eurasian plate making the Himalayas.
22
Q
What happens when two continental plates diverge
A
- First the land will collapse in on itself to create a rift valley
- Then magma will rise from the asthenosphere and cool and solidify to create new oceanic plate
- Magma will burst out of this plate creating a rift volcano
- Eventually water will fill the rift valley
- Earthquakes also occur here as the plates move apart
23
Q
What happens when an oceanic plate and continental/oceanic plate diverge
A
- Very similar to what happens when two continental plates diverge
- Except sea floor spreading happens here
- Magma will rise and create new oceanic plate
- Submarine volcanoes can form and can sometimes rise above sea level creating islands.
24
Q
Describe conservative boundaries
A
- Plates move in a parallel manner, this could be opposite directions or same direction at different speeds
- Zone of shearing, creates friction which causes stresses which are released causing earthquakes
- Does not matter what type of plate they are
- Rock is displaced as the plates rub past each other so rock sticks out of the ground
25
Why do volcanoes happen far away from plate boundaries
- A plume (a hot tower of unusually hot magma from the outer core) often can break through the lithosphere as it has lots of energy which causes volcanoes
- The magma from these volcanoes cool and solidify to create an island
- The plume doesn't move so the plate drifts over the plume and a new volcano is created, therefore creating an island arc
- The islands get eroded as they drift further away from the plume meaning they get smaller.
26
Why do earthquakes happen away from plate boundaries?
- Ancient crust - solid crust cracking as it travels over millions of years
- Associated with smaller magnitude earthquakes
- Can create a new plate boundary e.g. The East African Rift Valley
27
What is magma that has risen to the surface of the earth classed as?
Lava
28
Explain the Volcanic Explosivity Index
- Logarithmic scale: each number is 10x bigger
- It is based on volume of tephra (everything released by a volcano) and eruption column height
- The two don’t always correlate
- 8+ are known as ‘mega-colossal’ and are world changing, last one was approx 26,000 years ago - Mt Taupo in NZ
- Biggest in human history is Mt Tambora (Indonesia) was a 7
29
Explain why volcanoes occur on a convergent (destructive) boundary
- Oceanic crust subducts under the continental due to its density
- This begins to burn as it is forced into the hotter asthenosphere
- The area where the plate burns is called the Benioff Zone
- This creates new magma, pressure is built and a magma chamber forms
- This finds weaknesses in the lithosphere above it and, with enough pressure, will break the surface of the earth
- Eruptions tend to occur at the same place as it’s the easiest route for the pressurised magma to take
- Destructive boundaries build up significant pressure and tend to have the most explosive eruptions
- The Indo-Australian plate subducts under the Eurasian plate, why’d caused the Mt Semeru Eruption in 2021
30
Explain why volcanoes happen on a divergent boundary
- Plates diverge
- This creates a gap in the lithosphere but the underlying asthenosphere is highly pressurised. Therefore magma rises to fill the gap left
- These tend to have low explosivity
- Iceland sits on a divergent boundary as the Eurasian and North American plate move apar
31
Explain why volcanoes occur on a plume
- Magma plumes exist in several global locations
- The column of unusually hot magma is able to break through the lithosphere where a volcano is created
- These tend to be low explosivity but vary
- Hawaii would have no volcanoes if not for plumes. Iceland has a plume which brings more rhyolitic lava to the surface
32
Describe basaltic magma
- Can erupt almost continuously
- Low viscosity
- 1-2% of silica
- 50% gas content
- Not explosive
- Shield volcano
- Hawaii
33
Describe andesitic magma
- Decades or centuries between eruptions
- Medium viscosity
- 3-4% silica
- 60% gas content
- Medium explosiveness
- Composite volcano
- Mt.St Helens
34
Describe rhyolitic magma
- Erupt rarely
- Can be devastating
- High viscosity
- 4-6% silica
- 70% gas content
- High explosiveness
- Cinder cone volcano
- Yellowstone
35
Why is Iceland so complex?
- Sits on a divergent boundary and a plume
- Causes multiple different types of volcanic landforms and different types of magma because a plume can form any type of volcano
36
Describe a Plinian eruption
- Biggest in terms of VEI
- Huge column of tephra
- Often only small amounts of lava
- More likely to be explosive
37
Describe a Pelean eruption
- Pyrocrastic flow: collapses down volcano
- More rhyolitic
38
Describe a Hawaiian eruption
- Almost all lava
- Basaltic
39
Describe a subduction earthquake
- As oceanic plate subducts, there is significant pressure in the Benioff Zone. Due to constant pressure, often produces highest magnitude.
- Pressure is released as seismic energy - an earthquake
- Subduction of Pacific plate under the Eurasian caused the Japanese 2011 Tsunami
40
Describe a collision earthquake
- As two continental plates converge, pressure is built between them. These create thrust vaults. Pressure is released as seismic energy, an earthquake
41
Describe a strike-slip earthquake
- Intense pressure where plates rub against each other and get stuck on a conservative plate boundary.
- Pressure released as seismic energy - earthquake
42
Describe a shield volcano
- Basaltic lava than - least viscous - travels long distances - takes longer to cool
- near continuous eruptions
- as it gets old vent area can collapse in on itself
- Long, shallow slope
43
Describe a composite volcano
- steep profile with a summit volcano
- Rhyolitic lava - highly viscous - explosive
- common at subduction zones
44
Describe a caldera volcano
- magma chamber is emptied
- structural support above magma chamber is lost
- Ground surface collapses downward into chamber
- usually fill with water
45
Describe a cinder cone volcano
- bowl shaped crater
- steep, conical hill of loose pyroclastic flow fragments
- as gas charged lava is blown into air - breaks into small fragments that solidify and fall as cinders
- low viscosity lava
46
Describe batholiths
- When a plate stops subducting - it has been completely destroyed
- the volcano gets eroded except for the magma chamber as it is very resistant
- Leaves magma chamber on its own
47
What are extrusive and intrusive landforms
Extrusive - forms on surface of earth
Intrusive - forms under the surface of the earth
48
Describe primary (body) waves
- Fastest (6km per second)
- Reach the surface first
- Like sound waves
- Travel through mantle and core all around the world
- Not too damaging
- Cause other waves
49
Describe secondary (body) waves
- 4km per second
- High frequency but shake like a skipping rope
- Travel through mantle but not core
- 360 rolling motion
- Not always devastating
50
Describe Rayleigh (surface) waves
- Radiate from epicentre in a rolling motion on the surface
- 1km per second
- Causes ground deformation
- Move like ocean waves
51
Describe love (surface) waves
- 1km per second
- Cause the most damage
- Decay very slowly
- Perpendicular to the direction of P waves
52
What degree manner are seismic waves released in
360 degree manner
53
What determines tsunami size
- Magnitude of earthquake
- Depth of earthquake
- Depth of sea above epicentre
- Proximity to land
- Coastal landscape
54
Describe a tsunami
- Could be caused by an earthquake or volcano, 90% of the time it is an earthquake
- Earthquake occurs at sea - releases seismic energy to water above in 360 degree manner - with enough magnitude these 360 degree waves could travel thousands of miles
- Water rushes from beach to fill gap left by displacement of water - shoaling
- Further out at sea the amplitude is low and travelling at around 900km/h, when the tsunami approaches coast it slows down due to friction and grows in height as water gets more shallow - creates a wall of water travelling at around 60km/h
55
What are the four hazards of a volcano?
- Volcanic fallout - tephra ranging from a few mm to a metre - falls globally, injure, pressure on infrastructure, contaminate water supplies, impact global air travel, global temp. Soufriere Hills eruption in Montserrat
- Lava flows - generally slow, 2000 degrees approx, almost impossible to stop, destroy vegetation and property. Almost constant in SE Hawaii
- Pyroclastic flows - Fast moving currents of hot gas and volcanic matter, 400kmh approx 400 degrees approx. Travel over water - gain speed and steam is added, heavy material drops. White Island eruption
- Poisonous gases - Volcanoes under lakes or calderas emit gases (CO2) get trapped under sea bed. Earthquake or landslide releases this (limnic eruption) suffocating people. Cameroon 1986
56
Give three types of tephra and their diameter
Volcanic bombs - >64mm
Lapilli - 2mm to 64mm
Ash - <2mm
57
Give the three secondary impacts of volcanoes
- Mudflows and lahars - When ash, soil and rock changed to clay by acids in volcanic gases and hot spring waters. Very powerful. Eruptions under lakes, melting of snow on volcano, heavy rainfall mixing with volcanic material, pyroclastic flows entering water. Destroy most property, part of distal hazard zone. Mt Semeru
- Flooding - Sediment from fallout can block rivers causing local flooding. Can also lead to snow and ice melt on volcanoes, rise in discharge levels. Jökulhlaup, occur frequently in Iceland
- Tsunamis - small - submarine volcanoes, collapse of a volcano into sea or landslide travels into water. Tonga prone to volcanic tsunamis
58
Give the four long term issues of volcanoes
- Health - respiration issues from tephra, contamination of water supplies (cholera), long term trauma (mental health issues)
- Lifestyles - Destroy land - people need to relocate for residential or work reasons. Lava (nutrients). Indonesian authorities permanently relocated 5000 people after 2021 eruption
- Economics - LICs (struggle to rebuild infrastructure). Can lead to a growth in tourism (Iceland doubled its tourists after 2010 eruption)
- Environments - Large scale eruptions can block sunlight due to ash. Small scale and very rare.
59
What are the 6 main impacts of an earthquake
- Infrastructure collapses
- Buildings and homes collapse: poorly built suffer pancake effect
- Vital transport networks damaged (restricting access and aid)
- Glass and debris cause injury and death
- Evacuation can cause stress, panic and even heart attacks
- On water based geologies, like sandstone, liquefaction can occur
60
Give a piece of evidence each for the pancake effect and death over panic from earthquakes
- Poor building design in Nepal contributed to death toll as many pancaked
- Over 60% of deaths in 2011 Japan tsunami were those 65+. The stress of evacuation caused heart attacks
61
Give the 4 secondary impacts of earthquakes
- Broken power lines cause fires to spread. Wooden houses in LICs, open fires on homes
- Aftershocks, further energy released, cause further damage to already vulnerable communities
- Aid cannot reach, spread of disease, made worse by no removal of dead bodies
- Landslides and avalanches triggered due to seismic energy
62
Give a piece of evidence each for aftershocks and avalanches by earthquakes
- 25 aftershocks of more than 5 MMS in 2015 Nepal
- Avalanche on Mt Everest, killed 22
63
Give the four hazards of a tsunami
- Drowning - high speed waters
- Injury - large objects strike humans
- Contamination - salt water
- Water return - water recedes as it loses energy, causes more damage
64
What is a global event, a global hazard and a global disaster?
Global event
- A natural weather or earth occurrence
Global hazard
- The natural event that has the potential to cause death or damage
Global disaster
- The hazard causes deaths (>10) and/or damage (>$1M)
65
What is the disaster equation?
Vulnerability x Hazard = Capacity to Cope
66
Give the Hazard Profile and briefly describe what they mean
- Magnitude - How much energy e.g. MMS or VEI
- Duration - How long did the event go on for including secondary impacts?
- Frequency - How often does this occur? Are people used to this? Can they recover?
- Speed of Onset - How much warning did people have? Were they obvious warnings?
- Areal Extent - What are was affected?
- Spatial Predictability - Does it occur in the same area of the world often?
67
What two hazard profiles are negatively correlated?
Magnitude and frequency
68
What are return periods?
How often a place is likely to get a hazard e.g Japan is likely to get 100 to 200 7.0 magnitude earthquakes a year
69
What is a physical vulnerability?
- Some places naturally get more hazards due to ;plate boundaries, plumes and coastal towns etc.
70
Give 4 human vulnerabilities
- Population density - how many people living in area and are they densely packed
-Population demographics - Are there lots of old people. Old and young people like babies may be more vulnerable
- Reliance on technology - Do people act differently as they think technology will protect them
- Human attitudes - Do people feel fatalistic? Are they ‘trapped’ in the area due to economic pressures
71
Describe how the corruption in Syria worsened their vulnerability for the Turkey, Syria Earthquake 2023
- Affected Gaziantep, 6th largest city in Turkey (high density)
- Also going through a civil war
- 70% of buildings were not EQ proof due to building companies bribing officials to cut costs
- Some officials were accused of not sending out aid
- Some in Turkey believe in Kismet (fate determines life, do not prepare because they are ‘powerless’)
- Also felt safe because of previous low magnitude EQs
72
What are the three P’s and give an explanation for each of them and give evidence where necessary.
Prediction
- how accurately we can predict the location and magnitude of a hazard
-USGS (United States Geological Survey) help governments predict hazards globally
- EQs: cannot predict: P and S waves give a warning so people can prepare for L and R waves (California Shake Alert System)
- Tsunamis: Buoys float on sea, as soon as amplitude changes can predict where and height (Japan Dart System, Buoys record EQ)
- Volcanoes: Few days notice normally, sometimes false readings, not an exact science, can cause people to have a relaxed attitude, do not prepare, die (can predict by; increase in certain gases, water temp increase, mini EQs, changes in shape of ground)
Preparation
- What you do in advance, sometimes years before hazard
- Japan EQ education; EQ drills 2x a year, September 21st is national preparation day where local areas will have their own drills, public info campaigns, strict code for buildings, museums recognising disasters for cultural importance
Protection
- When hazard hits, protect lives and minimise damage
- Japan Emergency kits, has essentials to keep people alive for a few days
73
Describe LA Emergency Operations Centre
- Low and flat to provide stability
- Pipes are flexible
- Rollers which allow vertical and horizontal movement
- 911 based here
- Gas and electricity pipes not in ground
- Auto shutters prevent glass debris
74
Has the death rate from hazards increased or decreased and why?
Are there any exceptions?
Decreased
- Engineering ensures safer conditions
- More education on prevention and protection - Japan’s has become more efficient
- International coordination ensures shared knowledge and technology
- Aid organisations help prevent secondary impacts
BUT
- Turkey, Syria would have experienced an increase in deaths from hazards due to civil war going on
- Increase in aging populations mean more deaths due to vulnerability
- Rapid population density increase
75
Has the economic damage from hazards increased or decreased and why?
Are there any exceptions?
Increased
- More globalisation on technology means more can be damaged
- Insurance companies have to pay more
- Growth in TNCs means more damage to links - 2010 Icelandic Eruption; Kenyan farmer not able to import any of his flowers, Kenyan economy affected
- More infrastructure present (rapid urbanisation)
- Aid - other countries pay to help
- Rising expendable income means more personal property damage
BUT
- The number of aseismic buildings have increased due to countries developing, this decreased number of buildings damaged, minimising economic damage costs
76
Hazard reports have increased because….
- Technology can report more events USGS
- Population increases mean hazards more likely to affect people
- Research and education shared more between organisations
- Globalised world means inter-connectivity
-
77
Number of people affected by hazards has increased because…..
- Urbanisation means more people in dense living conditions
- Population increase means more can be affected
- More awareness of events due to technology
- Global network means more indirect impacts
78
What is a mega disaster?
Those which have significant global impacts
79
Why was the Japan 2011 Tsunami a Mega-Disaster?
- $100m+ damage in US
- Fukushima Nuclear Incident shaped worldwide views on this energy source
- Affected global sports
- Business building destroyed - global businesses affected
- Other tectonic countries learnt lessons
- Debris from tsunami washed up in Hawaii and West Coast US
- Earth’s axis shifted tens of centimetres
- Cancellation of flights: Tourism and business
- Oil refinery exploded - global import and export affected
- Tourist died from global countries - families affected
- G7 met to discuss issues with Japan’s currency
- Global NGO support
80
What temperature can pyroclastic flows get to and what is considered their maximum range?
1000 degrees Celsius and 15km
81
What term is given for floods created by glacial melt?
Jökulhlaup
82
What is the top layer of the earth known as?
The lithosphere
83
Where is the ‘Ring of Fire’?
Pacific
84
What term is given to magnetic readings of sea floors?
Paleo-magnetism
85
What is a multi hazard environment and what effects does it have on education, recovery and rehabilitation, economy and preparation and mitigation? Give an example of a multi hazard environment.
- Places which get several frequent, high magnitude hazards affecting a vulnerable population
- Education becomes a great challenge as there is more to educate on - every hazard has a different way to deal with - creates confusion - challenge to local authorities and people
- Recovery and rehabilitation becomes more difficult because community will not be able to recover from previous hazard in time for next one - things will still be under construction
- Greater strain on economy - money constantly spent on recovery and rehabilitation - more money is needed because different technology is needed for different hazards
- Preparation and mitigation is more difficult because it is hard to prepare for a hazard if one is currently going on - prepare differently for different hazards
- The Philippines is prone to EQs, landslides, tropical storms and volcanoes: it is a vulnerable population - high density and low income population
86
Describe relief, rehabilitation and reconstruction
Relief (24 to 48 hours)
- Aid
- Emergency hospitals
- Emergency shelter
- Search and rescue teams
- Food and water supplies
- Basic services restored
Rehabilitation (days and weeks)
- Reopening of jobs
- Build back systems
- Reopening of hospitals
- Repair water supplies
- Reopening of schools
- Temporary housing
- Transport back in place
Reconstruction (weeks and months)
- Permanent housing
- Permanent infrastructure
- Investments in better building systems may lead to a better quality of life
87
Give the order of the hazard management cycle and describe each stage
Mitigation to preparedness to response to recovery
Mitigation
- Efforts to reduce the effects or risks associated with hazards
Preparedness
- Actions taken prior to event to facilitate response and promote readiness
Response
- Actions taken during the event to save lives, property and the environment
Recovery
- Actions taken after an emergency to restore and resume normality
88
Explain modifying the cause of a tectonic hazard.
- To prevent the hazard at source. Difficult/impossible? For tectonic hazards
- Theory that we can depressurise a volcano, no evidence
89
Explain modifying a tectonic event
- the ability to control, avoid, resist; involves engineering, technology, building design, land use zoning etc.
- LA Emergency Operations Centre; Foundations on rollers (ground moves but buildings don’t), pipes in building not in ground, 911 operation centre, flat to increase stability
- Land management; people and infrastructure restricted in certain areas e.g. pyroclastic flows tend not to travel more than 15km. Indonesian Semeru eruption had a 1km restriction zone.
- Diversion strategies; lava can be diverted from populated areas through trenches if lava flow is predictable. Hawaii have prebuilt trenches
- Tsunami sea walls, however Japan’s was not high enough.
90
Explain modifying vulnerability
- Prediction, warning, preparedness (risk sharing), education
- Volcanoes, geographical prediction; years of data show which areas are most vulnerable. Small EQs, return periods, SO2 detection, ground deformation, thermal activity, tracking mass movement. Indonesia 2021, 4 days warning due to small landslides, however, 2014 mt Ontake gave very little warning.
- EQs; years of data show where most likely to occur, however does not apply to unknown micro plates. Cannot predict, USGS can only estimate probability (Nowcasting)
- Tsunamis; open ocean buoys and coastal ride guages. A tsunami watch goes into effect if EQ 7.5 or above. Evacuation happens accordingly. Japan uses DART system giving a 10-15 min warning.
- Education and drills(1st September Japan), early warning systems, preparedness (equipment and basic supplies), culture and attitudes (if people take it seriously, Japan)
91
Explain modifying the loss
- Emergency services - well trained with specialist knowledge. Japanese firefighters trained to understand lava flow movements and ash fall impacts
- Insurance - HICS, both personal and business, often have insurance which protects against losses. Insurance pay outs after Japan 2011 was £7b+
- International aid - Both governments and individuals donate money which aids for return to normality. Uk sent Nepal £33m after 2015 EQ
- Long term recovery - Governments may seek new opportunities or use Management Cycle to improve preparation in the next hazards. Iceland tourism has doubled since 2010 eruption
92
How did Japan and Nepal learn lessons from both of their EQs?
Japan 2011 - more public campaigns, changes to advice, study of collapsed buildings, more government funding for aseismic tech, stricter building codes, 2x number of people involved in September 1st
- Nepal 2015 - tried to implement many of these but were approx $4 billion short and 60% of Kathmandu buildings still don’t meet criteria.
93
What does spearman’s rank do and how many data points do you need to use spearman’s rank?
- Works out correlation between two variables
- Has to be at least 8 data points (better to have 10+)
94
Describe all the steps for working out spearman’s rank
1. Create a scatter graph (only for coursework) to tell if there is a basic relationship
2. Create a null hypothesis so no bias (no significant correlation)
3. Results have to be between 1 and -1, above 0 - positive correlation, below 0- negative correlation
4. Rank the two data sets, 1 meaning the biggest and 10 meaning the smallest
5. Find difference between ranks
6. Square these values and add up
7. Plug this number into 1-(6xED^2/n^3-n). ED^2 is the number from step 6, n is the number of rank pairs i.e how many rows there are on the table
8. Compare the answer to the critical rank table using 0.95 confidence and do n-2 to find the other row.
95
Give one reason why population density increased vulnerability
- More people are at risk of death or injury due to building collapsing on top of one another due to them being so densely packed
96
What does the term 'spacial predictability' mean?
How often a hazard occurs in an area which indicates how likely it is to occur in the future.
97
Which island nation is considered the most vulnerable in the world?
Vonvatu
98
Which city suffered significant liquefaction due to an earthquake?
Christchurch
99
Which targets do the UN use in order to reduce poverty and therefore vulnerability?
Reduce mortality of hazards, reduce economic loss, increase countries who have local plans, increase international cooperation and increase availability of early warning systems
100
Outline an example of how land zoning can protect against tectonic hazards
Infrastructure and people are restricted in certain areas to protect them from getting damaged by the hazard
