Tectonic EQ2

Created by: Yespacito
Created on: 08-01-20 21:52

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Tectonics EQ2
- From Hazard to Disaster
  - Models explaining risk and vulnerability
    - Risk Equation
      - Risk = (Hazard x Vulnerability x exposure)/ coping ability
        Increased risk if: hazard is stronger, more vulnerable, more people exposed, less able to cope.
      - Attempt to capture link between vulnerability, hazards, and why disasters occur
    - Pressure and release model: links vulnerability, hazards and disaster.
      - Vulnerability has a progression: root causes, dynamic pressures, unsafe conditions
        Root causes include access to power, infrastructure, political system.
        
        Unsafe conditions can mean crime, fragile economy, fragile environment.
        
        Disaster = hazard + vulnerability
      - If vulnerable and a hazard occurs (eg. earthquake) then can cause disaster.
        Disaster = hazard + vulnerability
      - Attempt to capture link between vulnerability, hazards, and why disasters occur
    - Degg's model
      - If a hazard occurs while a population is vulnerable and susceptible to loss, can cause disaster.
    - Swiss Cheese model: Each layer represents a factor in vulnerability, and holes are problems for a particular layer. Some layers have more holes, and it varies country to country. If holes line up in a single trajectory, hazard leads to disaster.
  - Reasons people live in vulnerable areas/are vulnerable
    - Predictability
      - Volcanoes more predictable than earthquakes so evacuation can occur earlier
    - Alternative areas
      - May be too poor to live elsewhere eg. in Haiti most in Port au Prince very poor so couldn't leave.
    - Cost - benefit: some areas worth risk eg. Japan has good enough opportunities to be worth tectonic risks
    - Resilience is helped by:
      - Evacuation systems
      - Hazard resistant design eg. cross-bracing or counterweight
      - Land use policy eg. no nuclear power in Japan post 2011 due to earthquakes
- Governance and risk
  - How development affects vulnerability
    - Social
      - Better health reduces disease risk.
      - Education means more trained in evacuation procedures
      - Better housing means kless likely to collapse and kill like it did in Haiti 2010.
    - Economic
      - Better wealth means better tech so warning systems improve eg. Japan send text to all phones 7 seconds after first P wave in 2011, compared to little warning in Haiti.
    - Politics
      - If more rights given, people more likely to trust gov and follow evacuation orders.
    - Environment
      - Better sanitation leads to less likely waterborne disease breakout eg. poor sanitation in Haiti 2010 led to 8000 cholera related deaths
  - Link between development and disasters.
    - How development affects disasters
      - Better food and water access leads to resilience
      - Tech reduces impacts because of warnings
      - Amount of provisions post-disaster
      - Better healthcare
      - Poor conditions mean death more likely
      - Development often breeds inequality (link to risk-poverty nexus)
    - How disasters affect development
      - Creates environment advocating risk reduction
      - Can build back better
      - Destroys assets so money lost
      - Damage to businesses reduces income
      - If many young people die, workforce decreases so economic activity decreases so it's harder to recover
      - Damaging health reduces labour force
        If many young people die, workforce decreases so economic activity decreases so it's harder to recover
    - Risk poverty nexus
      - Disaster creates loss
        Loss leads to poverty in the short and long term
        Different types of poverty occur eg. economic, social.
        Poverty leads to daily risks like food insecurity and crime
        These feed into long term risks that increase hazard exposure
        Disaster creates loss
        Loss leads to poverty in the short and long term
        Different types of poverty occur eg. economic, social.
        Poverty leads to daily risks like food insecurity and crime
        These feed into long term risks that increase hazard exposure
      - Model explains how inequality and poverty can lead to risk and how disasters can feed into more risk if handled poorly
  - Types of governance and role of governments
    - Economic governance: decisions about economic activity eg. where to spend money. If spent on hazard resistance, reduces chance of a disaster
    - Political governance: deciding what policies should be implemented to reduce hazard reduction eg. whether to make it required to carry out drills
    - Administrative governance: how to enforce policies eg. how building codes should be enforced
- Link between risk and hazards
  - Measuring Hazard scale
    - Richter scale: from 0-9, measures wave size. 1 unit increase means 10x wave size (logarithmic)
      - Absolute + objective value. Measured from location it hits so measures how it felt at area.
      - Doesn't allow simple comparison between countries' experience because wealth, evacuation etc. ignored
    - Mercalli scale: Measures earthquake from how it felt. From 1-12/I to XII. Higher means more shaking. Considers if it woke people, furniture movement, and structure damage.
      - Allows direct comparison of experience of the earthquake so comparison is easier.
      - Subjective because based on experienced damage so unscientific.
    - Moment magnitude scale (MMS): logarithmic scale showing energy of waves rather than wave size. Is most used measurement modern day.
      - Ignores wave dissipation so helpful for seismologists to compare tectonic movements.
      - Ignoring wave dissipation means that it is inaccurate to how it was felt at that location
    - Volcanic explosivity index (VEI): measures volume of ejecta from eruption (tephra, volcanic gases etc.). Measured 0-8 logarithmically
      - Objective because based on volume of ejecta.
      - Ejecta can't be measured directly so brings accuracy of measurement into question.
  - Hazard profiles
    - Used to understand physical features of a tectonic event.
    - Considerations
      - Magnitude
        Higher magnitude means more shaking so more structures lost.
      - Speed of waves
        Faster speed means less time between P waves and S/L waves so less time to escape more destructive waves
      - Duration
        Longer duration means more time for damage to happen
      - Areal extent
        Wider reach means more affected
      - Predictability
        Less predictable means higher impact due to less time to evacuate
      - Frequency
        Less frequent means more time for plate boundary pressure to build. Also reduces collective memory so less knowledge on what to do, especially in LICs
    - Evaluation
      - Help identify hazards to target in managing
      - Allow comparison of physical processes to see how they affected the hazard's impact.
      - Difficult to compare across hazards eg. volcano with earthquake

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Tectonic EQ2

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