Hazards

Question 1

What is a hazard?

Answer 1

• A hazard is an event which has the potential to cause harm to the environment, people or the economy
• Natural hazards occur when natural events interact with humans

Question 2

What does Degg’s model show?

Answer 2

• interaction of people and natural events overlapping is what leads to a natural disaster because harm occurs to the population

Question 3

How does the UN define the word disaster?

Answer 3

‘A serious disruption of the functioning of a community or a society involving widespread human, material, economic or environmental losses and impacts, which exceeds the ability of the affected community or society to cope using its own resources’

Question 4

What are 3 types of natural hazard?

Answer 4

Geophysical – caused by land processes eg. earthquakes, volcanic activity and mass movements
Atmospheric – caused by climatic processes – eg. tropical storms and wildfires
Hydrological – caused by the movement and distribution of water – eg. floods

Question 5

Factors affecting the severity of an event?

Answer 5

• magnitude
• population density
• preparedness
• scale
• economy
• demographic

Question 6

What is the influence of economic factors on hazard perception?

Answer 6

• Quality of housing and infrastructure is likely to be higher in wealthier areas – this may mean that people feel safer (dominance)
• Increased spending on preparation and prediction – this may mean that people are more aware of the risks and able to evacuate
• More investment in education – this may mean that people understand the potential dangers and are more likely to take action to minimise risk

Question 7

What is the influence of cultural factors on hazard perception?

Answer 7

• Cultural values and beliefs may affect whether people trust scientists and government officials – this may mean they underestimate the risk
• Some cultures believe that hazards are an act of God – this may mean that they don’t want to evacuate
• People who have previously experienced hazards may be more fearful – this may mean they are more prepared

Question 8

What is fatalism?

Answer 8

Fatalism is when people believe that hazards cannot be avoided and so must be accepted – this often leads to people doing nothing in response to hazards

Question 9

How can the risks of harm of a hazard be minimised?

Answer 9

• Prediction – using science and technology to predict where and when a hazard will occur so that warnings can be issued, potentially allowing people to evacuate
• Adaptation – changing behaviour to reduce potential losses – eg. improving awareness of hazards and practising earthquake drills
• Mitigation – working to reduce or prevent the occurrence of hazards – eg. building sea walls to prevent flooding in the event of a tsunami or tropical storm
• Integrated risk management – analysing potential risks and implementing a coordinated approach to manage and reduce risks
• Risk sharing – working together to reduce the risk and sharing the costs of hazard response – eg. buying home insurance – only some people need to claim but the cost is shared by everyone

Question 10

What are the main factors affecting hazard response?

Answer 10

• Incidence – how often a hazard occurs. The more often a hazard occurs, the more likely that people will be educated and prepared with effective management strategies in place
• Intensity and magnitude – the size, strength or severity of a hazard
  The greater the severity of a hazard, the larger the potential impact, and the greater the response required
• Distribution – where hazards occur
  In more hazardous locations people are more prepared for hazard events because they invest significant time and money to protect themselves
  Japan has invested in earthquake-resistant buildings and earthquake drills
• Level of development – the level of economic wealth and standard of living in a country. More developed countries are more likely to have mitigation and adaptation strategies in place and will be better prepared to respond to the hazard effectively

Question 11

What does the hazard management cycle show?

Answer 11

The hazard management cycle is a model that shows how the events of one hazard event inform planning and preparation for the next hazard event

Question 12

What are the stages of the hazard management cycle?

Answer 12

Response - Search and rescue and provision of emergency medical assistance and aid

Recovery - Restoring services and reconstruction of damaged buildings

Mitigation - Building flood barriers, setting up an early warning system

Preparedness - Earthquake drills, public awareness campaigns

• time taken during each stage varies from country to country based on factors such as level of development,
  magnitude of the hazard, quality of governance and aid available - has the greatest impact on response and recovery stage

Question 13

Outline the concept of the hazard management cycle?

Answer 13

• The hazard management cycle is a continuous loop which explains an approach to managing a known hazard
• Preparedness is concerned with using evidence and data from previous events to plan for hazards associated with the event. Good preparation is the key to minimising impact upon the population
• Response is concerned with deploying services and resources to save people and property from harm. Response is likely to involve emergency services such as fire and rescue teams in an earthquake
• Recovery is concerned with post disaster reconstruction and restoration of the local built and natural environment
• Mitigation is an extension to recovery. This is the active steps taken to minimise the negative impacts associated with the hazard. Constructing earthquake proof buildings or flood protection systems are examples of mitigation

Question 14

What does the park model show?

Answer 14

Park’s model shows how people’s quality of life is affected by hazards.
It also outlines how people respond to hazard events

Question 15

What does the vulnerability quadrant show?

Answer 15

physical exposure to hazards (risk) and human vulnerability to disaster (insecurity) - most vulnerable areas include places like Haiti with high risk and low security

Question 16

Why are some people more vulnerable to hazards?

Answer 16

• poverty and weak economy
• failing political systems
• lack of education/training
• rapid urbanisation

Question 17

What 3 stages does the park model show?

Answer 17

Relief – the immediate response including search and rescue, provision of emergency medical assistance and aid
Rehabilitation – a longer phase that includes temporary restoration of services and infrastructure e.g. temporary schools and shelters are set up
Reconstruction – permanent restoration which aims to provide the same or an improved quality of life than before e.g. through the rebuilding of infrastructure using aseismic designs

Question 18

What are the 4 types of hazard perception?

Answer 18

• fatalism - losses are accepted as inevitable so people remain where they are
• adaptation - people see that they can prepare for and survive events by prediction/prevention and protection, dependent on economic and technological circumstances
• fear - people feel so vulnerable that they can no longer live in the area
• dominance - hazards can be predicted and understood better through scientific research

Question 19

How can perceptions of a population be changed?

Answer 19

• education by governments - increased perception of fear so population more likely to evacuate - less risk to life
• adaptation so strategies can be implemented to reduce impacts eg. earthquake proof buildings - however this may increase perceptions of dominance due to reliance on technology

Question 20

What is integrated risk management?

Answer 20

• identification of the hazard
• analyse risks
• establish priorities
• implement a risk reduction plan
• monitor and review the whole process

Question 21

What is community resilience?

Answer 21

• sustained ability of a community to utilise available resources to respond to, withstand and recover from the effects of a natural hazard
• resilient communities can minimise the effects and make return to normal life as effortless as possible

Question 22

How is the hazard management cycle used?

Answer 22

• appropriate actions at all stages of the cycle lead to greater preparedness, better warnings and reduced, or the prevention of hazard events during the next cycle
• leads to a greater capacity to deal with disasters so recovery is more rapid and long-lasting

Question 23

Evaluate the hazard management cycle?

Answer 23

positives:
- encourages planning before so reduced impacts
- good for areas experiencing hazards infrequently who have the capacity to manage them
- certain areas can be prioritised
- can be applied to all hazards - flexible and relevant model
- long-term focus - builds resilience and long-term recovery/mitigation over time

negatives:
- not all countries can afford it - eg. LICs lack funding and governance to effectively implement all stages
- often much greater focus on response rather than mitigation/preparedness
- overlooks social factors - applied in a top-down way
- recovery may take years or fail entirely - disparities in recovery efforts

Question 24

Evaluate the park model

Answer 24

positives:
- visual and easy to understand - good for comparisons between similar hazards and clearly illustrates recovery process over time
- can be adapted for different events
- analyses resilience - shows whether or not a country has come back stronger
- takes into account temporal patterns

negatives:
- recovery isn’t always smooth or linear
- doesn’t account for inequality eg. assumes uniform recovery but ignores vulnerable groups
- doesn’t address compound hazards
- no focus on mitigation/preparation
- no spatial patterns - some areas may have been impacted much more than others

Question 25

Evaluate the 2 models together

Answer 25

- HMC includes mitigation and preparation which is essential in reduced loss of life and property, proactive rather than reactive so communities become more resilient - PM shows timeline of recovery and how quickly areas bounce back - effective in showing response and recovery but doesn't help to prevent future disasters - HMC more effective in protecting populations before an event, PM more effective at evaluating effectiveness after an event but limited in ability to reduce future risk

Question 26

How can the PM and HMC be used together?

Answer 26

- provides a comprehensive timeline - before, during and after - preparedness and mitigation from HMC influence steepness of PM curve - HMC is more policy focused eg by governments, PM reflects real human experience so together combine top-down and bottom-up perspectives

Question 27

What is the structure of the earth?

Answer 27

- crust - made up of continental (thicker and less dense) and oceanic (thinner and more dense) - mantle - upper mantle made up of 2 layers, rigid layer above the asthenosphere which together with the crust makes up the lithosphere, and the asthenosphere which moves very slowly under high pressure - inner and outer core

Question 28

How does the earths structure drive tectonic movement?

Answer 28

the core is the hottest part of the earth, and this heat drives tectonic activity - heat caused by radioactive decay of elements inside the core, and heat left over from collisions of asteroids - causes movement of the lithosphere

Question 29

What is the continental drift theory?

Answer 29

- suggests that the earths continents had once been a part of a single land mass called Pangea - over millions of years the continents have gradually drifted apart, however in the past they were unable to explain why - now the basis of the modern theory of plate tectonics - tectonic plates slowly move over the asthenosphere

Question 30

How are convection currents used to explain tectonic movement?

Answer 30

- Heat from radioactive decay in the core moves upwards in the mantle - It creates convection currents which rise towards the surface before spreading in the asthenosphere, cooling and sinking - As they reach the asthenosphere they carry the lithospheric plates above with them - Other processes are now recognised as being important in plate movement (gravitational sliding/ridge push and slab pull)

Question 31

What is gravitational sliding/ridge push?

Answer 31

- New oceanic crust is formed at mid-ocean ridges and stands 2-3km above the ocean floor - As the crust moves away from a mid-ocean ridge, it cools and becomes denser and thicker - This causes the lithosphere to slope away from the ridge and gravity pulls the lithosphere down this slope, pushing it forwards - Ridge push is much less important than slab pull in causing the movement of tectonic plates

Question 32

What is slab pull?

Answer 32

- A subduction zone is formed when two plates move towards each other - The heavier, denser oceanic plate subducts under the lighter, less dense plate - As the plate sinks, gravity pulls the plate down into the mantle - The edge of the subducting plate is much cooler and heavier than the mantle, so it continues to sink, pulling the rest of the plate along with it - Slab pull is more powerful than ridge push because it is driven by gravity acting on the cooler, denser crust

Question 33

What is sea floor spreading?

Answer 33

- The process where new oceanic crust forms at mid-ocean ridges as magma rises and solidifies - Palaeomagnetism provides evidence that the sea floor has gradually moved apart at a mid-ocean ridge, as lava cools and solidifies with the minerals lining up with the magnetic field - The earths polarity reverses at regular intervals resulting in a series of magnetic stripes with rocks aligned alternately towards the north and south poles - The direction of the minerals on either side is a mirror image suggesting that the oceanic crust slowly spreads away from this boundary - The theory implies that the earth must be getting bigger, but oceanic trenches form where large areas of ocean floor are being subducted

Question 34

What are the processes driving plate movement?

Answer 34

- convection currents - gravitational sliding - slab pull - sea-floor spreading

Question 35

What are the 3 types of plate boundary?

Answer 35

Constructive (divergent) - plates move apart or diverge Destructive (convergent) - plates move together or converge Conservative (transform) - plates sliding past each other

Question 36

What are the landforms created at constructive margins?

Answer 36

- ocean ridges - rift valleys

Question 37

What are ocean ridges and how do they form?

Answer 37

- underwater mountain ranges that form at divergent boundaries where 2 oceanic plates move apart - form when magma rises from the mantle through the gap created by the separating plates - as the magma cools and solidifies it builds up to form a ridge - over time, continuous eruptions and plate movement causes the ridge to grow, forming features like the Mid-Atlantic ridge

Question 38

What are rift valleys and how do they form?

Answer 38

- Long, narrow depressions in the Earth's surface formed at divergent plate boundaries on continental crust - As the plates move apart, it causes the crust to stretch and thin and the brittle crust fractures as sections of it move apart - Areas of crust drop down between parallel faults due to gravity to form rift valleys - eg. where the African plate is splitting, the East African Rift Valley has formed

Question 39

What features form at destructive plate margins?

Answer 39

- deep sea trenches - fold mountains - island arcs

Question 40

What are deep sea trenches and how do they form?

Answer 40

- Long, narrow depressions in the ocean floor found at convergent plate boundaries - Where oceanic and continental plates meet, the denser oceanic plate is subducted under the lighter, continental plate into the mantle - This creates a steep-sided trench in the subduction zone - eg. Mariana Trench where the pacific plate is subducting under the Philippine plate - often form alongside island arcs

Question 41

What are fold mountains and how do they form?

Answer 41

- Large mountain ranges formed at convergent plate boundaries where 2 continental plates collide as a result of slab pull/ridge push - Both plates are of a similar density and therefore neither is subducted - This causes the continental plate to become compressed and deformed, buckling and folding due to pressure - The crust is formed upwards creating folds in the rock layers, forming high mountain ranges like the Himalayas, where the Indian and Eurasian plate collide

Question 42

What are island arcs and how do they form?

Answer 42

- Curved chains of volcanic islands that form at oceanic-oceanic convergent plate boundaries - During subduction, the descending plate encounters hotter surroundings and this coupled with the heat generated from friction begins to melt the plate - As this material is less dense than the surrounding asthenosphere, it slowly rises to the surface as plutons of magma - Eventually the magma rises through the overriding plate to form complex, composite explosive volcanoes - If the eruptions take place offshore, a line of volcanic islands form as the volcanoes emerge above sea level - eg. Mariana islands run parallel to the Mariana Trench

Question 43

How do the different processes occurring at each boundary influence the magnitude of the eruption/earthquake?

Answer 43

- At constructive margins: Earthquakes tend to be mild and shallow Volcanic eruptions tend to be less explosive - At destructive margins: Friction and pressure build up in the Benioff zone (the area within the subduction zone where most friction and pressure build up occurs) causing strong earthquakes Volcanic eruptions tend to be explosive as the magma is forcing its way to the surface - At conservative margins: Plates can stick causing a significant build up of pressure and powerful earthquakes

Question 44

What are magma plumes and hotspots?

Answer 44

- in certain places, a concentration of radioactive elements below the crust causes a hotspot to develop - from this, plumes of magma rise from deep within the mantle forming active volcanoes above the hotspot, away from plate boundaries - as the plates move over the stationary hotspot, chains of volcanoes form eg. the Hawaiian islands in the Pacific Ocean - as the Pacific plate moves, a line of volcanoes is created so scientists can measure plate movement over time, volcanoes become extinct as the plate moves away and the oldest islands are the ones furthest from the plume

Question 45

How do volcanoes form at destructive boundaries?

Answer 45

- denser oceanic plate subducts beneath the continental plate as it is denser - as the subducting plate descends into the mantle it melts due to high pressure and friction forming magma - magma is viscous, trapping gases and building pressure and rises through cracks in the crust, creating explosive composite volcanoes

Question 46

How do volcanoes form at constructive boundaries?

Answer 46

- as the plates diverge, magma rises from the mantle to fill the gap which creates new oceanic crust - because the magma is basaltic, it flows easily producing gentle shield volcanoes

Question 47

How do volcanoes form at hotspots?

Answer 47

- mantle plumes brings magma to the surface due to areas of radioactive decay in the core causing temperatures to rise - this forms a chain of volcanoes