HISTORY OF ENGINEERINGBASED EARTHQUAKE CASUALTY MODELING

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HISTORY OF ENGINEERING-BASED EARTHQUAKE CASUALTY
MODELING
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Research Participants Sponsor

• Hope A. Seligson, Kimberley I. Shoaf, Corinne
  Peek-Asa, And Maya Mahue-Giangreco
  
• Support for this research was provided by
  National Science Foundation Grant Numbers
  CMS-9900062 and CMS-0085314
  

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Definitions

• Engineering-based earthquake casualty models
  predict building damage-related casualties (and
  in some cases, other types of casualties). These
  models have typically been developed by engineers
  from limited anecdotal, historical data (not from
  epidemiological studies, nor involving
  health-related researchers).
• These models are typically used for emergency
  response, planning and mitigation by government
  agencies at various levels, but are less useful
  for health preparedness planning.

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1970s NOAA Scenarios

• NOAA published scenarios in 1972 (SF Bay area)
  and 1973 (LA area) that estimated
  building-related casualties.
  
• Tabulated aggregate damage and casualty
  statistics for historic earthquakes.
  
• Used generalized casualty rates per 100,000
  population based on previous earthquakes.
  
• Mystery ratios of 41 serious injuries (i.e.,
  requiring hospitalization) to deaths and 301
  minor injuries to deaths.
  
• Included estimates for sidewalk deaths and
  freeway collapse.
  
• The final results were judgment-based, scenario
  specific casualty estimates, rather than a
  broadly applicable casualty estimation methodology

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1980s ATC-13 and Expert Opinion

• In 1985, the Applied Technology Council (ATC-13)
  took a more comprehensive look at estimating
  building damage for classes of structures using
  expert opinion.
• Percent damage and damage state for 17 structural
  classes are estimated from Modified Mercalli
  Intensity (MMI), similar to earlier work by
  Whitman, et. al (1974).
• Mean casualty rates associated with damage
  states, were applied to the exposed population.
  Rates based on historic EQs, previous models and
  judgmental evaluation
• Mystery ratios still in use.

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ATC-13 Casualty Rates
Note for light steel and wood-frame
construction, multiply all numerators by 0.1
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1990s State of the Art Computer Models -
HAZUS (NIBS/FEMA)

• Uses advanced ground motion parameters and
  detailed engineering analyses to determine
  building damage states and associated damage
  state probabilities. Represents a significant
  advance in the automated application of loss
  estimation techniques.
• Indoor and outdoor casualty rates by damage state
  and model building type, based on ATC-13 and
  limited historical data for 4 injury severity
  levels
• Injuries requiring basic medical aid
• Hospitalized
• Life threatening Injuries
• Deaths

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HAZUS Earthquake Loss Estimation Methodology -
Indoor Casualty Rates (HAZUS99, SR-2)
Notes URM unreinforced masonry, LRWF
low-rise wood frame, HR URMI high rise steel
or concrete frame structures with URM Infill
walls, MH mobile home, SLF steel, light
frame, HR PC high rise precast concrete
structures
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More State of the Art Computer Models EPEDAT

• EPEDAT (Early Post-Earthquake Damage Assessment
  Tool) was developed by ABS Consulting/ EQE
  International for the CA Office of Emergency
  Services. It is a GIS-based program designed to
  produce regional damage and casualty estimates
  for emergency response and planning purposes.
• For casualty models, Beta distribution applied to
  ATC-13 and Whitman casualty rates to distribute
  casualties within range of potential damage in
  each damage state (i.e., more injuries with more
  damage in a given damage state).

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Current Research Earthquake Data and
Opportunities for Improvement

• NSF (and other funding) allowed researchers
  (inter-disciplinary team from UCLA, LA County
  DHS, and ABS/EQE) to collect and correlate data
  from the Northridge and other earthquakes
• building characteristics and damage data
• coroners data
• hospital admission data
• ED logs
• Survey data on damage and injuries
• Research goal capitalize on the high-quality
  data to improve the way engineering-based models
  estimate building-related casualties, and make
  the results more meaningful to health care
  providers.

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Application of Northridge Data

• Comparison of model prediction to actual
  Northridge data to develop after-market
  modifications that make results more useful to
  medical community.
• Translates estimates of Injuries and Deaths
  to
  
• Fatalities (non-hospital, i.e., DOA)
• Fatalities requiring hospital care (i.e., ICU)
• Trauma cases
• Non-Trauma Hospital Admissions
• ED Treat Release
• Out of Hospital Treatment

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Refinements to EPEDATs casualty models for
injury planning and response
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Additional Research Products

• A literature review of the medical,
  epidemiological, public health, and engineering
  literature. See http//www.ph.ucla.edu/cphdr/proj
  ects.html.
• Development of a standardized classification
  scheme for all aspects of earthquake-related
  casualties (e.g., injury mechanism, building
  damage). See http//www.ph.ucla.edu/cphdr/scheme
  .pdf
• An integrated review of available casualty and
  damage data (e.g., Northridge, Kobe, Nisqually
  EQs) classified according to the new
  classification scheme - in progress.

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Conclusions

• Engineering-based casualty models allow for rapid
  estimation of regional population impacts for
  response, planning and mitigation purposes.
  While many advances have been made in the area of
  loss estimation, casualty modeling has not
  received the attention dedicated to the
  development of other model components.
• Future enhancement of the such models will
  benefit greatly from coordinated data collection
  and analysis, as well as inter-disciplinary
  research incorporating medical and public health
  perspectives. This integrated approach will
  facilitate the use of data from recent and future
  events to refine engineering-based casualty
  models.

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Standardized Classification Scheme for
Earthquake-Related Injuries
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Purpose of Standardized Classification Scheme

• To establish a systematic, multi-disciplinary and
  collaborative approach to the study of risk
  assessment, loss estimation for earthquakes
  
• To create a common language to define the event,
  the victims and responses for any given
  earthquake
  
• Reduce variability of data for reported deaths
  and injuries

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Components of Classification Scheme
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Use of Existing Measures

• Abbreviated Injury Score
• International Classification of Diseases, 9th.
  Revision
  
• ATC 20

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Hazard Level Variables

• Earthquake Source
• Earthquake Name
• Event Number or ID
• Magnitude
• Magnitude Scale
• Date
• Time
• Day of Week
• Earthquake Location
• Rupture Length

• Rupture Area
• Presence of Surface Rupture
• Deepest Point of Rupture
• Shallowest Point of Rupture
• Fault Source
• Local Site Hazard
• Earthquake ground motion
• Local Site Conditions

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Building Level Variables

• Building Description
• Structural System
• Building Height
• Building Size
• Building Year
• Seismic Design Quality
• Debris Generation Potential
• Occupancy Type
• Estimated Occupancy
• Actual Occupancy

• Building Damage
• Building Safety Inspection Status
• Safety Tag
• Dollar Damage
• Damage Percent
• Damage State
• Building Collapse

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Individual Level Variables

• Demographics
• Age
• Gender
• Race/Ethnicity
• Level of Education
• Occupation
• Income
• Disabilities and Pre-existing Conditions

• Injury Characteristics
• Cause of Injury
• Relation of EQ
• Structural Relatedness
• Secondary Hazards
• Injury Mechanisms
• Injury Severity
• Treatment
• Level of Treatment
• Immediacy
• Diagnoses
• Costs
• Direct Medical Care Costs
• Indirect Costs

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Individual Level Variables, cont.

• Location
• Injured individuals physical location
• Injured individuals geographic location

• Activity
• Starting position
• Activity