Earthquake Loss Estimation

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Earthquake Loss Estimation
Session 3 Mr. James Daniell
Risk Analysis Earthquake Risk Analysis
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Learning Objectives

• Learn how to undertake an earthquake loss
  estimation
• Know how to convolve the hazard, exposure and
  vulnerability using damage loss conversion and
  uncertainties
• Know what socio-economic loss components are
  needed in an earthquake loss estimation
• Know where earthquake risk analysis fits into
  earthquake risk management.
• Know what global software tools are available to
  undertake an earthquake loss estimation
• Understand that there are many uncertainties that
  can only be quantified by earthquake loss
  estimation engineers.

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Why do we undertake Earthquake Loss Estimation?
The number of earthquakes are the same but
exposure is increasing, therefore losses are
increasing

• Total Economic losses for earthquake and
  secondary effect events from Jan 1900 Marc
  2010, CAT DAT Damaging Earthquake Catalogue
• Developing Country Losses
• Developed Country Losses

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Earthquake Loss Estimation - towards mitigation

• Earthquake loss estimation is the combination of
  three main factors hazard, vulnerability and
  asset value.
• Losses are the decrease in asset value resulting
  from damage.
• Losses are typically given in terms of the number
  of damaged assets, or as a cost such as the
  cost to replace or repair the damaged assets.
• Acceptable Risk and Cost-Benefit Analysis
• Loss estimation studies are very useful tool for
  developing emergency preparedness plans and for
  promoting seismic risk mitigation.

Seismic Risk, loss, mitigation, acceptable risk,
cost-benefit.

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Earthquake Loss Estimation
Adapted from RiskScape, 2009

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What influences damage-loss conversion?
Population Density
Magnitude, depth duration of EQ source
Distance from quake source

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Damage-Loss Conversion

• After the vulnerability assessment, the
  infrastructure damage is expressed as the no. of
  infrastructure per geocell, in a damage state
  (none to collapse) or as a damage ratio with
  variability.
• A relationship of economic and social loss
  estimates for each of these damage states is
  needed!
• If the scenario is changed, building damage needs
  to be recalculated.

Age Pre-1970 Pre-1970 Post-1970 Post-1970
Type URM Timber URM Timber
Geocell B 0.269 0.151 0.077 0.055
Geocell E 0.811 0.603 0.396 0.269
OR

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Direct vs. Indirect Impact
Earthquake Impacts
deaths, injuries, homeless, evacuated and
affected population
calculated via empirical historical EQ ratios of
losses, or analytical numerical models
Social
repair and reconstruction costs associated with
infrastructure damage
direct
Economic
Psycho-social trauma, weakening of institutions,
Social
a consequence of the direct physical damage
associated with the earthquake
indirect
Business interruption, diminished production and
services
Economic
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Direct Economic Loss Conversion

• The replacement cost is usually calculated
  multiplying the floor area, construction cost per
  unit area, number of buildings and number of
  storeys.
• Empirical repair ratios can be derived for each
  of these damage levels vs. the entire replacement
  cost.
• Repair/Replacement Mean Damage Ratio (MDR)

• Local construction and cost data, production
  material, demolition and debris removal,
  lifeline, government law and social data are
  needed!

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Direct Social Loss Conversion

• This includes both empirical and analytical
  social death, injury and homeless, evacuated,
  affected population ratios for conversion from
  building damage estimates.
• Much uncertainty development level!
• Given the damage levels, occupancy data is
  required per building given a certain time of
  day.
• It is also important to identify large social
  loss areas, like marketplaces, schools and
  stadiums.

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Direct Social Loss Conversion

• KOERI (2002) give deaths as the number of
  severely damaged (D4) and collapsed (D5)
  buildings.
• An expert opinion system gave serious injuries as
  4x deaths.
• There are many empirical casualty rate models.
• Region-specific usually.

Spence, 2007
Jaiswal et al., 2009

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Indirect Socio-Economic Loss Conversion

• Modelling indirect effects is difficult due to
  lack of data and complexity of relationships
  between indirect and direct effects!
• Two types hazard dependent and hazard
  independent.

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Earthquake Loss Consequences
Outputs of earthquake loss estimation
Adapted from SYNERG, 2009

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Earthquake Loss Assessment for mediation and
mitigation

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Using the earthquake cycle to protect against
Earthquakes and Secondary Hazards

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Earthquake Loss Estimation Tools

• Many tools that can be used depending on the
  desired model, use and data availability
• open source or proprietary
• for real-time monitoring
• complex or simple
• empirical or analytical
• Some example of non-proprietary tools
• HAZUS-MH (North America) scenario risk analysis
  for hurricane, earthquake and floods.
• CAPRA (Central America) probabilistic risk
  analysis to the analysis of hurricane,
  earthquake, volcano, flood, tsunami and landslide
  hazards.
• RADIUS excel-based tool for preliminary
  estimation of damage in developing countries
• GEM currently being developed as the first
  global earthquake model

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