Earthquake resilience

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Earthquake resilience

  1. 1. Resilience Against Earthquakes Some Practical Suggestions for Planners and Managers David Alexander Global Risk Forum - Davos (CH)
  2. 2. What is resilience [resiliency]?• a combination of resistance and adaptation (coping, capacity, capability)• ability to maintain livelihoods and tenor of life in the face of disaster shocks• local autonomy and self-sufficiency. self-sufficiency.
  3. 3. Redundancy Redundancy Redundancy RedundancyThe ingredientsof resilience Adaptability Attitude Participation ...and communication
  4. 4. Source: World Disasters Report 2005 Wisdom: ability to take decisions on the basis of principles, principles, experience and knowledge Knowledge: understanding of how things function (or should function) Information: description of physical and social situations Data: basic facts and statistics COMMUNICATION
  5. 5. Knowledge Knowledge of of hazards community and their vulerability impacts DRR Knowledge of copingDisaster capacity and Risk resilienceReduction
  6. 6. Community disaster planning Volunteerism Donations Self- Self-organisation Community resources Organisation Resources Imposed Governmental organisation resources Laws, protocols, directivesStandards, norms, guidelines International resources
  7. 7. Organisationneed not beexpensive andthe cost ofcommunicationis continuallyfalling...
  8. 8. Vehicles are an important source ofpeoples vulnerability to earthquakes, but...
  9. 9. Vernacular housing: the main source of riskThis is where we need resilience...
  10. 10. A simplemethodologycould determinewhich part of ahouse is leastliable to damagein an earthquakeand whatpatterns ofdamagemight occur.
  11. 11. Can we devise a strategy to enhanceself-self-protective behaviour?
  12. 12. A scale for damage and personal risk level Damage level: [1] minimum damage level: to walls, fitments and furniture. walls, furniture. Personal risk level: prudent level: behaviour will minimise risks. risks.
  13. 13. A scale for damage and personal risk level Damage level: [2] significant damage level: to structures, cladding and fitments. Personal risk level: significant level: risk of injury but not of death. .
  14. 14. A scale for damage and personal risk level Damage level: [3] general damage and level: collapse of architectural elements. Personal risk level: significant risk of level: injury but relatively low risk of death.
  15. 15. A scale for damage and personal risk level Damage level: [4] serious damage level: or partial collapse of building. Personal risk level: strong risk of level: injury and significant risk of death.
  16. 16. A scale for damage and personal risk level Damage level: [5] collapse of level: more than 50% of the structure. Personal risk level: limited and mainly level: unpredictable probability of survival.
  17. 17. Q E Poor building Proximity quality Injuries to epicentreQ (low seismic and fault E resistance) rupture Deaths Concentration T of casualties S Topographic SedimentaryT amplification amplification S CC = f { E,Q,S,T }
  18. 18. Building quality and seismic resistance: • site factors
  19. 19. Building quality and seismic resistance: • building type and materials [Masonry] [Reinforced concrete]
  20. 20. Building quality and seismic resistance: • plan and elevation of building
  21. 21. Building quality and seismic resistance: • urban form factors [battering by adjacent buildings]
  22. 22. Building quality and seismic resistance: • mixed construction? [Stone and concrete block]
  23. 23. Building quality and seismic resistance: • state of maintenance
  24. 24. Building quality and seismic resistance: • occupancy factors
  25. 25. One needs to investigate the relative importance of these factors in different situations site urban form factors factors building type mixed and materials construction? plan and elevation of building
  26. 26. Mid-floor damage to multi-occupancy bldg: Intertia effect Interaction = damage Lack of stiffness in frameBasal acceleration
  27. 27. For example... what is the typicalpattern of seismic failure of Iranianvernacular housing of any given type?
  28. 28. Some possible modes of failure • basal acceleration • inertial displacement • spalling of façade • torsion • ejection of infill masonry • deformation of structural nodes • detachment of internal stairways
  29. 29. In the case of total collapse, littlecan be done for the occupants of abuilding except urban heavy rescue.This is up to three times more likely to be successful if the location of trapped occupants is known (e.g. they can attract attention). attention).
  30. 30. An example: the LAquila (Italy) earthquake of 6 April 2009
  31. 31. n=202 6-25 deaths 3-5 deaths 1-2 deaths One or two individuals No deaths Clustersof multiple deaths LAquila city
  32. 32. No deaths: housing stock was in relatively good condition anddamage was limited Damage/risk scale: 1-2 1-
  33. 33. One or two individuals:people rushed outside and were killed by falling masonry Damage/risk scale: 3-4 3-
  34. 34. ... or inthe collapseof stairwells.
  35. 35. Clusters of multiple deaths:spectacular collapses of multi-occupancy multi- buildings with up to 25 deaths each: topographicamplification was an additional factor. factor. Damage/risk scale: 5
  36. 36. Unexpected earthquake Mild Severe Catastrophic impact impact impact Very Fall of Partial Total limited heavy collapse collapse damage objects Remain Seek Seek in situ potential place of Rush cavity refuge outside Lightly Seriously Uninjured Killed injured injuredAbsolute immobility Frantic egress
  37. 37. Earthquake scenario• magnitude range• maximum accelerations• recurrence intervals, etc.Seismicperformanceof buildings• modes of failure• typologies of damageRisk factors• behaviour of building occupants during earthquakes• effectiveness of search and rescue
  38. 38. Models of typicalvernacular housing building types Analysis of characteristic failure modes Determination of appropriate crisis behaviour Education and training of households Culture of protection and resilience
  39. 39. Resilience against earthquakes: Ten suggestions for action
  40. 40. Tell people what to do in an earthquake.
  41. 41. Develop urban search and rescue capacity on site.
  42. 42. Reduce non-structural as non-well as structural hazards.
  43. 43. Plan flexibly.
  44. 44. Create networks.
  45. 45. Encourage governance.
  46. 46. Adapt and disseminate good practice.
  47. 47. Ensure that Disaster Risk Reduction(DRR) programmes are sustainable
  48. 48. Create a strategy for recovering from the next disaster.
  49. 49. Create a culture of resilience against disasters.
  50. 50. ...and avoid the myth of panic:it should not be treated as a relevant factor in emergency planning
  51. 51. Thank you for yourattention! david.alexander@grforum.org emergency-planning.blogspot.comThis presentation can be downloaded from:- www.slideshare.com/dealexander

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