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L'Aquila Earthquake


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L'Aquila Earthquake

  1. 1. Self-protective behaviour duringearthquakes: some lessons fromLAquila, 6 April 2009David AlexanderUniversity College London
  2. 2. Analysis• registered• archived• forgotten• ignoredVulnerabilitymaintained-• utilised• adopted• learnedDisasterriskreduced+LessonsPasteventsThe process ofdisaster riskreduction(DRR)
  3. 3. But what lessons?Lets go and see...
  4. 4. The earthquake03.32 hrs, Monday 6 April 2009Magnitude: Mw 6,3Duration: circa 25 sec.Acceleration on hard rock: 0,3gAcceleration on sediments: 0,7-1,0gPart of an earthquake swarmthat began in October 2008.
  5. 5. At the world scale, most injuriesoccur in nocturnal earthquakes:• a sleeping person is notable to react rapidly• vernacular housing is particularly at risk• 50-90% of mortality is nocturnal.
  6. 6. A bracketed duration of 50 secondswould have caused thousands of deaths.
  7. 7. Deaths: 308Injuries: 1,500(202 serious,& 898 triaged)Homeless people:67,500Tent camps: 171Tents: 5,700 (for8 people each)
  8. 8. LAquila:-• a university city• population 72,800• 14 outlying villagesMunicipalities reporting damage:-• 49 in the government decree• 96 in total• 81 in Abruzzo Region• 16 seriously damaged.
  9. 9. Opi-Pescasseroli1984Avezzano 1915• 32,000 deaths• 10,700 of themin Avezzano city(pop. 11,400)Other earthquakesin Abruzzo:
  10. 10. Deaths in the LAquila earthquake:-• dominated by age groups 20-29 and 70+• an excess of females, especiallyin age groups 30-39 and 70-79• the excess of females cannot beexplained purely by demographics• if mortality had followed the M/F andage-group distribution of the population,it would have been 168, not 308.
  11. 11. • death/injury ratio = 0.20 (low)• case fatality rate = 0.17 (low), 0.41-0.60 for serious injuries (rather high)• ratio of serious to all injuries = 0.13(50-70% of the expected value).Deaths in the LAquila earthquake:-
  12. 12. How aggregate behaviour factorsaltered the distribution of injuries:-Negative: presence of many universitystudents in sub-standard accommodation.Positive: earthquake occurred at the endof the weekend - many people had notreturned home (and they never would!).
  13. 13. 24 km11kmDistribution of deaths in theLAquila earthquake of 6/4/09LAquilaOnna
  14. 14. Earthquake of 6 April 2009 at LAquila:Mortality by age-group and sex
  15. 15. (n=308)(n=202)
  16. 16. 6-25 deaths 3-5 deaths 1-2 deathsClustersof multipledeathsn=202LAquila cityOne or two individualsNo deaths
  17. 17. • one fifth to one quarter of deathsoccurred in only seven buildings• deaths were clustered in areasof topographic amplificationand poor quality buildings• the location of deathscorresponds closely with partialand total building collapse.Distribution of deaths in LAquila centre• apart from student housing, deathclusters were not particularlydifferentiated by age group
  18. 18. What if the earthquake hadoccurred at another time of day?When people would have been in church:-• serious damage to religious buildingsA working day during business hours:-• very serious damage to public buildings• much masonry fell into narrow streets• many vehicles were crushed• serious damage to LAquila hospital.
  19. 19. LAquila Prefecture:identified to be at highseismic risk in a reportdated June 2008.
  20. 20. Incipient collapse of intermediate floorscaused by lack of stiffness in structure.Column breakageTypical forms of damage in RC
  21. 21. Collapse of intermediate floor causedby battering by adjacent retaining wall.Typical forms of damage in RCTwo deaths
  22. 22. Collapse of soft storey groundfloor which had insufficient stiffness.Typical forms of damage in RC
  23. 23. Typical forms of damage in RCDetachment, fragmentationand expulsion of infill walls.Rackingfailure
  24. 24. Typical forms of damage in URMBLoad-bearing walls disintegrate at angles.
  25. 25. Typical forms of damage in URMBExcessively heavy roof in RC: subsides.
  26. 26. Typical forms of damage in URMBDetachment of facade elementsand fall of roof tiles.
  27. 27. Preparedness is thwarted by:-• lack of experience and directcontact with the problem• lack of adaptability and inadequateperception of the need to adapt• insufficient perception tostimulate a person to take action• social: lack of communicationand sharing of the problem• economic: failure to accumulate wealthand failure to invest in protection• organisation: lack of a facilitatingsocial structure and incentives.
  28. 28. Ten reasons not to run outsideduring the earthquake• battering by adjacent structures• fragmentation, collapse of masonry walls• detachment of roofs• detachment of balustrades and chimneys• balconies demolished by falling masonry• separation of masonry walls from roofs• expulsion of infill walls in RC structures• detachment and collapse of wall angles• detachment and collapse of stairs• distorsion (racking) of apertures.
  29. 29. Eight reasons for not remainingin buildings• detached beams batter down walls• torsion and fragmentation of RC nodes• detachment and collapse of RC roofs• cracking of weaks zones in walls• implosion and collapse of walls in RC• detachment of stucco and plaster• damage to ceilings and internal fitments• overturning of furniture.
  30. 30. Douglas Copps triangle of lifewould not have worked in LAquila.Neither would sheltering under a table.Probably the best response would havebeen to retreat further into the building.
  31. 31. Seekplace ofrefugeRemainin situSeekpotentialcavityRushoutsideUnexpected earthquakeMildimpactSevereimpactCatastrophicimpactVerylimiteddamageFall ofheavyobjectsPartialcollapseTotalcollapseAbsolute immobility Frantic egressUninjuredLightlyinjuredSeriouslyinjuredKilled
  32. 32. A scale for damage and personal risk levelDamage level: [1] minimum damageto walls, fitments and furniture.Personal risk level: prudentbehaviour will minimise risks.
  33. 33. Damage level: [2] significant damageto structures, cladding and fitments.Personal risk level: significantrisk of injury but not of death.A scale for damage and personal risk level
  34. 34. Damage level: [3] general damage andcollapse of architectural elements.Personal risk level: significant risk ofinjury but relatively low risk of death.A scale for damage and personal risk level
  35. 35. Damage level: [4] serious damageor partial collapse of building.Personal risk level: strong risk ofinjury and significant risk of death.A scale for damage and personal risk level
  36. 36. Damage level: [5] collapse ofmore than 50% of the structure.Personal risk level: limited and mainlyunpredictable probability of survival.A scale for damage and personal risk level
  37. 37. Poor buildingquality(low seismicresistance)Proximityto epicentreand faultruptureTopographicamplificationSedimentaryamplificationQ ET SConcentrationof casualtiesCC = f { E,Q,S,T }DeathsInjuriesQ ET S
  38. 38. A possible survival strategyIdentify the safest part of the house:-• fall of tiles or collapse of entire roof• stability of facade and cornices• solidity of stairs for egress• detachment of beams and risk thatthey will batter down the building• use of heterogeneous materials givingrise to a complex seismic response.
  39. 39. • avoid risky behaviour• create an exit strategy• identify a safe place toreach near to the house• identify the most dangerous partsof the house and how to avoid them• create a mutual support networkof friends, relatives and neighbours• collect and store useful equipment• train family members andtest your reaction plan.A possible survival strategy
  40. 40. Thank youvery muchfor listening.
  41. 41.