Analysis of mortality patterns in the 2009 l'aquila earthquake


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Analysis of mortality patterns in the 2009 l'aquila earthquake

  1. 1. Mortality Patterns inEarthquakes: the Exampleof LAquila, 6 April 2009 David Alexander University College London
  2. 2. "Now, what I want is, facts. Teach these boys and girls nothing but Facts. Facts alone are wanted in life. Plant nothing else, and root out everything else. You can only form the minds of reasoning animals upon Facts: nothing else will ever be of any service to them. This is the principle on which I bring up my own children, and this is the principle on which I bring up these children. Stick to Facts, sir!" Thomas Gradgrind in Hard Times by Charles Dickens
  3. 3. Towards an evidence-based approach to earthquake epidemiology
  4. 4. The earthquake 03.32 hrs, Monday 6 April 2009 Magnitude: Mw 6.3 Duration: circa 25 sec. Acceleration on hard rock: 0.3g Acceleration on sediments: 0.7-1.0g Part of an earthquake swarm that began in October 2008.
  5. 5. Deaths: 308Injuries: 1,500 (202 serious, & 898 triaged)Homeless people: 67,000Tent camps: 171Tents: 5,700 (for 8 people each)
  6. 6. Deaths in the LAquila earthquake:-• dominated by age groups 20-29 and 70+• an excess of females, especially in age groups 30-39 and 70-79• the excess of females cannot be explained purely by demographics• if mortality had followed the M/F and age-group distribution of the population, it would have been 168, not 308.
  7. 7. Deaths in the LAquila earthquake:-• 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).
  8. 8. FatalinjuriesSerious high ratioinjuries low ratio Allinjuries low ratio
  9. 9. After more than 30 years of study, the relationship between injury anddamage patterns is still poorly understood.
  10. 10. Characterising damage
  11. 11. Typical forms of damage in RC Column breakageIncipient collapse of intermediate floorscaused by lack of stiffness in structure.
  12. 12. Typical forms of damage in RC Two deaths Collapse of intermediate floor causedby battering by adjacent retaining wall.
  13. 13. Typical forms of damage in RC Compressed ground floorCollapse of soft storey groundfloor which had insufficient stiffness.
  14. 14. Typical forms of damage in RCRackingfailure Detachment, fragmentation and expulsion of infill walls.
  15. 15. Typical forms of damage in URMLoad-bearing walls disintegrate at angles.
  16. 16. Typical forms of damage in URMExcessively heavy roof in RC: subsides.
  17. 17. Mid-floor damage to multi-occupancy bldg: Intertia effect Interaction = damage Lack of stiffness in frameBasal acceleration
  18. 18. 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
  19. 19. Detachment of façade elements and fall of roof tiles.
  20. 20. Algeria 2003 LAquila 2009 Stairwell collapse
  21. 21. Q E Poor quality Proximity InjuriesQ building (low seismic to epicentre and fault E resistance) rupture Deaths Concentration T S of casualtiesT Topographic amplification Sedimentary amplification S CC = f { E,Q,S,T }
  22. 22. A practical earthquake epidemiology Focus Potential benefit to... Self-protective How, where behaviour and why people died; Urban searchwho they were; and rescue how they (USAR) reacted tothe earthquake Hospital mass-casualty response
  23. 23. Behavioural influence on casualtiesActive behaviour:• journey to and from work• recreational activities, etc.• family life at homePassive behaviour:• sleeping at night• role, efficiency and rapidity of search and rescue and medical assistance after the earthquake.
  24. 24. The ratio of deaths to collapsed buildings varies from 8:100 to 32:100 Entrapment increases the risk of death by 35-100 times• respiratory difficulties caused by pressure of fallen objects on the thorax or ingestion of large amounts of dust• 2-6 hours after the earthquake fewer than half of trapped people are still alive.
  25. 25. Percentage of people trapped alive under the rubble of collapsed buildings 0 100 50 Hours 0.5 1 3 12 Critical period Survival time Days 1 2 3 45 7 10 15Source: Coburn and Spence (2002)
  26. 26. These are the people who died in the 6th April 2009LAquila (central Italy) earthquake
  27. 27. Abruzzo Region Preturo LAquila Tempera Province LAquila PaganicaEpicentre Poggio Bazzano San di Roio Roio Gregorio Piano Pianola Onna Poggio Bagno Picenze Tornimparte Fossa San Demetrio Lucoli ne Vestini San Pio Villa delle Camere SantAngelo 10 km
  28. 28. Location of deaths (by town), n=3081 8 5 202 2 1 1 2 39 8 5 1 12 4 1 3 5 17
  29. 29. DeathsSantAngelo di Bagno Poggio di Roio Civita di Bagno Tornimparte Pianola Fossa Poggio Picenze Tempera Villa SantAngelo LAquila 0 50 100 150 200
  30. 30. Null hypothesis: no factors of ageor gender increased the probability of being killed in the earthquake.
  31. 31. Average Age of Victims (by town), n=30873.0 66.5 56.8 51.1 66.5 57.0 74.0 69.5 60.6 60.6 22.8 8.0 77.083.0 52.7 56.0 26.0 26.0 61.6 57.5
  32. 32. LAquila City: location of deaths of 30-39-yr olds 6 1 5 2 2 2 2 2 4 2 4 1 Total collapse of house, single death: 3F 2 2 Collapse of house kills entire family: 6F/2M 2 3 Total collapse of house: slow death: 1F Male 1 1 4 Partial collapse of house: 2M Female 3 5 Crushed by beam: 1F 6 Not known: 1F
  33. 33. Area of roof and Area of stairwell collapse: comparatively limited casualties light damage and no casualties Area of Area of sporadic topographic damage andamplification, few casualties with major damage and casualties 500 m
  34. 34. To NE: unreinforced masonryAll victims in buildingsLAquila city To SW: centre area reinforced n=186 concrete buildings Male Female
  35. 35. Pensioners disaster area Students Topographic amplificationdisaster area Roof and stairwell collapse Sporadic damage Light damage (no deaths)
  36. 36. Older people were moreaware of the danger but lesswilling or able to react to it.Females, especially old ladies, weremore inclined to passive behaviour.Males, especially old men, were moreinclined to try to get out of the building.Old people were moreinclined to behave passively.
  37. 37. Implications• self-protection potentially saves lives• inability or unwillingness to react increases the danger• women more inclined to treat house as refuge• old men better at self protection than old ladies?.
  38. 38. Conclusions
  39. 39. Disproved hypotheses:-• men and women were doing different things when quake struck• clustering of male and female deaths• people died more readily in URM than RC buildings• average age of victims higher in small settlements• women died trying to save children and men did not.
  40. 40. In the LAquila data set, above the age of 70 there were 19-24% more deaths than predicted by local demographic profiles, amounting to 59-74 individuals out of 308.Old people - calculated excessover the demographic predictor:-• Women: 40 (13% of total mortality)• Men: 19 (6.2% of total mortality).
  41. 41. "More research is needed"
  42. 42. Thank you very much for listening!