Tectonics - EQ3.8

Theoretical frameworks can be used to understand the predication, impact and management of tectonic hazards.

Equation for risk

Risk = (Hazard x Vulnerability) / Capacity to cope

Degg’s model

• Hazards should not be confused with natural disasters

• A disaster only happens when a vulnerable population encounters a hazard

• If the population is not vulnerable, the disaster will have little effect and not be disastrous

Equation for risk

Risk = (Hazard x Vulnerability) / Capacity to cope

Degg’s model

• Hazards should not be confused with natural disasters

• A disaster only happens when a vulnerable population encounters a hazard

• If the population is not vulnerable, the disaster will have little effect and not be disastrous

Classifying a tectonic hazard

• International Disaster Database = a disaster is when 100+ are affected and 10+ die

• UNISDR = a serious disruption of the functioning community or society involving widespread losses and impacts which exceed their capacity to cope

• The economic cost of the disaster should also be considered e.g. jobs lost, cost of repairs, economic productivity lost

The Park Model

A graphical representation of human responses to hazards showing the steps carried out overtime of the recovery after a hazard

• The steepness of the curve shows how quickly an area deteriorates + recovers

• The depth of the curve shows the scale of the disaster

Park - Stage 1 - Relief - hours to days

• Immediate local response

• Immediate appeal for foreign aid

Park - Stage 2 - Rehabilitation - days to weeks

• Services begin to be restored

• Temporary shelters + hospitals set up

• Food + water distributed

• Coordinated foreign aid e.g. peacekeeping forces

Park - Stage 3 - Reconstruction - weeks to years

• Restoring the area to the same (or better) quality of life

• Area back to normal - ecosystem restored, crops grown etc.

• Infrastructure rebuilt

• Mitigation efforts for a future event

Park - comparison with other hazards

The Park disaster response curve acts as a control line to compare hazards.

An extremely severe hazard would have a steeper curve and a slower recovery line

The Pressure and Release Model (PAR)

Used to analyse factors which cause a population to be vulnerable to a hazard

One side has the hazard itself whilst the other has factors and processes which increase a populations vulnerability to the hazard

PAR - Root causes

Often caused by economic, demographic and/or political processes which affect large populations or entire countries

PAR - Dynamic pressures

Local economic or political factors that can affect a community or organisation

PAR - Unsafe conditions

The physical conditions that affect an individual e.g. unsafe building, low income, poor health

PAR - Progression of vulnerability

The number of people affected will increase the closer the factor is to the root cause

Example of the PAR model

• Unsafe conditions - A lack of infrastructure, e.g. poor sewage, can worsen the impacts of a hazard as it’s harder to maintain clean living conditions. This lack of infrastructure would be a factor of unsafe conditions

• Dynamic pressure - However, this lack of infrastructure may be due to rapid urbanisation where little planning had been taken to carefully construct house and infrastructure to cope with this. Rapid urbanisation would be the dynamic pressure

• Root cause - Ultimately, planning and controlling safe population growth is the governments responsibility, so the root cause of this disaster may have been weak governance

Common Root Causes (PAR)

• Weak governance

• Mismanagement by Industry, NGOs or IGOs

• High reliance on products easily affected by hazards e.g. agriculture

Common Dynamic Pressures (PAR)

• Lack of training/knowledge in locals

• Rapid urbanisation

• Poor communication between government and locals

• Lack of basic services e.g. health, education

Common Unsafe Conditions (PAR)

• Lack of infrastructure e.g. clean water, sewage removal

• Dangerous location of settlements e.g. close to the hazard itself

• No warning system for locals

• Disease and fire can spread easily between households

Types of vulnerability

• Physical - living in a hazard prone area

• Economic - people risk losing employment, wealth or assets during a hazard

• Social - communities are unable to support their disadvantaged, leaving them at risk

• Knowledge - individuals lack training or warning to know the risks or a hazard + how to evacuate safely

• Religious - religion + beliefs may limit their understanding; they are an act of God so don’t mitigate (fatalist beliefs)

• Environmental - increased risk due to high population density

Tectonic Hazard Profiles

Compare the physical characteristics which all hazards share.

They can help decision makers when deciding where to allocate the most human and financial resources

The characteristics of a hazard profile

• Frequency - How often it happens

• Magnitude - Size of hazard

• Duration - How long the event lasts

• Speed of onset - Warning before occurence

• Spatial predictability - Is there a pattern to where it happens

• Areal Extent - How big of an area does it cover

Evaluating the effectiveness of models

They can be useful, but the unpredictability of hazards make them less effective at accurately representing human responses to hazards

• Can they be applied to every hazard? Do some need a more complex model?

• Does it take any aspects of hazards into account like development?

• Is there any timeframe?

• Could the model be less vague and include more steps?

• Does it present hazards currently and taken account of climate change?

VEI - Volcanic Explosivity Index

• Measures relative explosiveness of a volcanic eruption

• Based on height of ejected material and duration

• Scale goes from 0-8

• Increase of 1 on the scale indicates a 10x more powerful eruption (logarithmic)

The Modified Mercalli Scale

• Measures the destructiveness of an earthquake

• Relative scale as people feel different amounts of shaking in different places

• Subjective - it’s based on waking up, furniture moving + damage to structures

• Scale varies from I to XII

• I = not very severe

• XII = Nearly total destruction

Moment Magnitude Scale

• Measures amount of energy released in an earthquake

• Scale from 0-9

• Environmental or social impacts must be inferred as it’s a simple measure

Richter Scale

• Measures magnitude of waves produced during an earthquake

• Most widely used scale as it’s absolute

• Must infer social or environmental impacts which can be misleading

  • The highest scale earthquake readings won’t necessarily be the worst disasters

• Logarithmic (x10 per scale increase like VEI)

• Technically no upper limit