1. Prof. David AlexanderProf. David Alexander
CESPROCESPRO - University of Florence- University of Florence
Earthquakes and HousingEarthquakes and Housing
How to Develop a Survival StrategyHow to Develop a Survival Strategy

2. PastPast
eventsevents
PastPast
eventsevents
AnalysisAnalysis
• registeredregistered
• archivedarchived
• forgottenforgotten
• ignoredignored
• registeredregistered
• archivedarchived
• forgottenforgotten
• ignoredignored
VulnerabilityVulnerability
maintainedmaintained..--
• utilisedutilised
• adoptedadopted
• learnedlearned
• utilisedutilised
• adoptedadopted
• learnedlearned
DisasterDisaster
riskrisk
reducedreduced
++
LessonsLessonsLessonsLessons

3. • 3030 disasters (including seismic seawaves)disasters (including seismic seawaves)• 3030 disasters (including seismic seawaves)disasters (including seismic seawaves)
• 47,35047,350 deaths (varies from year todeaths (varies from year to
year by two orders of magnitude)year by two orders of magnitude)
• 47,35047,350 deaths (varies from year todeaths (varies from year to
year by two orders of magnitude)year by two orders of magnitude)
• 8.58.5 million people affectedmillion people affected• 8.58.5 million people affectedmillion people affected
• $23$23 billion in damagebillion in damage
(second only to hurricanes)(second only to hurricanes)
• $23$23 billion in damagebillion in damage
(second only to hurricanes)(second only to hurricanes)
• 60%60% of disasters occurred in Asiaof disasters occurred in Asia..• 60%60% of disasters occurred in Asiaof disasters occurred in Asia..
Mean annual impact of earthquakes
(1999-2008 data)

4. At the world scale, most injuriesAt the world scale, most injuries
occur in nocturnal earthquakes:occur in nocturnal earthquakes:
• a sleeping person is nota sleeping person is not
able to react rapidlyable to react rapidly
• vernacular housing is particularly at riskvernacular housing is particularly at risk
• 50-90% of mortality is nocturnal50-90% of mortality is nocturnal..

5. VernacularVernacular
housing:housing:
the mainthe main
sourcesource
of riskof risk

6. A scale for damage and personal risk levelA scale for damage and personal risk level
Damage level:Damage level: [1][1] minimum damageminimum damage
to walls, fitments and furniture.to walls, fitments and furniture.
Personal risk level:Personal risk level: prudentprudent
behaviour will minimise risksbehaviour will minimise risks..

7. Damage level:Damage level: [2][2] significant damage
to structures, cladding and fitments.
Personal risk level:Personal risk level: significant
risk of injury but not of death..
A scale for damage and personal risk levelA scale for damage and personal risk level

8. Damage level:Damage level: [3][3] general damage and
collapse of architectural elements.
Personal risk level:Personal risk level: significant risk of
injury but relatively low risk of death.
A scale for damage and personal risk levelA scale for damage and personal risk level

9. Damage level:Damage level: [4][4] serious damage
or partial collapse of building.
Personal risk level:Personal risk level: strong risk of
injury and significant risk of death.
A scale for damage and personal risk levelA scale for damage and personal risk level

10. Damage level:Damage level: [5][5] collapse of
more than 50% of the structure.
Personal risk level:Personal risk level: limited and mainly
unpredictable probability of survival.
A scale for damage and personal risk levelA scale for damage and personal risk level

11. Survival strategies
could be improved
for levels 1-4
but perhaps not
for level 5
(total collapse)

12. Poor buildingPoor building
qualityquality
(low seismic(low seismic
resistance)resistance)
ProximityProximity
to epicentreto epicentre
and faultand fault
rupturerupture
TopographicTopographic
amplificationamplification
SedimentarySedimentary
amplificationamplification
QQ EE
TT SS
ConcentrationConcentration
of casualtiesof casualties
CC
C =C = ff { E,Q,S,T }{ E,Q,S,T }

13. Building quality and seismic resistance:Building quality and seismic resistance:Building quality and seismic resistance:Building quality and seismic resistance:
• site factorssite factors

14. Building quality and seismic resistance:Building quality and seismic resistance:Building quality and seismic resistance:Building quality and seismic resistance:
• building type and materialsbuilding type and materials
[Masonry] [Reinforced concrete][Masonry] [Reinforced concrete]

15. • plan and elevation of buildingplan and elevation of building
Building quality and seismic resistance:Building quality and seismic resistance:Building quality and seismic resistance:Building quality and seismic resistance:

16. Building quality and seismic resistance:Building quality and seismic resistance:Building quality and seismic resistance:Building quality and seismic resistance:
• urban form factorsurban form factors
[battering[battering
byby
adjacentadjacent
buildings]buildings]

17. Building quality and seismic resistance:Building quality and seismic resistance:Building quality and seismic resistance:Building quality and seismic resistance:
• mixed construction?mixed construction?
[Stone and[Stone and
concreteconcrete
block]block]

18. Building quality and seismic resistance:Building quality and seismic resistance:Building quality and seismic resistance:Building quality and seismic resistance:
• state of maintenancestate of maintenance

19. Building quality and seismic resistance:Building quality and seismic resistance:Building quality and seismic resistance:Building quality and seismic resistance:
• occupancy factorsoccupancy factors

20. An example:An example: the L'Aquila (Italy)the L'Aquila (Italy)
earthquake of 6 April 2009earthquake of 6 April 2009
An example:An example: the L'Aquila (Italy)the L'Aquila (Italy)
earthquake of 6 April 2009earthquake of 6 April 2009

21. L'Aquila:-L'Aquila:-
• a university citya university city
• population 72,800population 72,800
• 14 outlying villages14 outlying villages
96 municipalities reported damage96 municipalities reported damage

22. The earthquakeThe earthquakeThe earthquakeThe earthquake
03.32 hrs, Monday 6 April 200903.32 hrs, Monday 6 April 2009
Magnitude MMagnitude Mww 6,36,3
Duration 25 secondsDuration 25 seconds
Acceleration on hard rock 0,3gAcceleration on hard rock 0,3g
Acceleration on sediments 0,7-1,0gAcceleration on sediments 0,7-1,0g
Part of an earthquake swarm fromPart of an earthquake swarm from
October 2008 to July 2009October 2008 to July 2009..
03.32 hrs, Monday 6 April 200903.32 hrs, Monday 6 April 2009
Magnitude MMagnitude Mww 6,36,3
Duration 25 secondsDuration 25 seconds
Acceleration on hard rock 0,3gAcceleration on hard rock 0,3g
Acceleration on sediments 0,7-1,0gAcceleration on sediments 0,7-1,0g
Part of an earthquake swarm fromPart of an earthquake swarm from
October 2008 to July 2009October 2008 to July 2009..

23. Significance of the L'Aquila disaster:Significance of the L'Aquila disaster:
• It was a relativelyIt was a relatively small eventsmall event withwith
a disproportionatelya disproportionately large impactlarge impact
• It was a relativelyIt was a relatively small eventsmall event withwith
a disproportionatelya disproportionately large impactlarge impact
• Medium-size earthquake disastersMedium-size earthquake disasters
are more common than large onesare more common than large ones
and deserve to beand deserve to be studied morestudied more..
• Medium-size earthquake disastersMedium-size earthquake disasters
are more common than large onesare more common than large ones
and deserve to beand deserve to be studied morestudied more..

24. 24 km
11km
Distribution of deaths in the
L'Aquila earthquake of 6/4/09
L'AquilaL'Aquila
OnnaOnna

26. 6-25 deaths 3-5 deaths 1-2 deaths
No deathsNo deaths
One or two individualsOne or two individuals
ClustersClusters
of multipleof multiple
deathsdeaths
n=202
L'Aquila city

27. No deaths:No deaths:
housing stock washousing stock was
in relatively goodin relatively good
condition andcondition and
damage was limiteddamage was limited
No deaths:No deaths:
housing stock washousing stock was
in relatively goodin relatively good
condition andcondition and
damage was limiteddamage was limited
Damage/riskDamage/risk
scale: 1-2scale: 1-2

28. One or two individuals:One or two individuals:
people rushed outsidepeople rushed outside
and were killed byand were killed by
falling masonryfalling masonry
One or two individuals:One or two individuals:
people rushed outsidepeople rushed outside
and were killed byand were killed by
falling masonryfalling masonry
Damage/riskDamage/risk
scale: 3-4scale: 3-4

29. Clusters ofClusters of
multiple deaths:multiple deaths:
spectacular collapsesspectacular collapses
of multi-occupancyof multi-occupancy
buildings with upbuildings with up
to 25 deaths each:to 25 deaths each:
topographictopographic
amplification was anamplification was an
additional factoradditional factor..
Clusters ofClusters of
multiple deaths:multiple deaths:
spectacular collapsesspectacular collapses
of multi-occupancyof multi-occupancy
buildings with upbuildings with up
to 25 deaths each:to 25 deaths each:
topographictopographic
amplification was anamplification was an
additional factoradditional factor..
Damage/riskDamage/risk
scale: 5scale: 5

30. Mid-floor damage to multi-occupancy bldg:
Intertia effectIntertia effect
Basal accelerationBasal acceleration
Interaction = damageInteraction = damage
Lack of stiffness in frameLack of stiffness in frame

31. Incipient collapse of intermediate floorsIncipient collapse of intermediate floors
caused by lack of stiffness in structure.caused by lack of stiffness in structure.
Column breakageColumn breakage
Typical forms of damage in RCTypical forms of damage in RCTypical forms of damage in RCTypical forms of damage in RC

32. Collapse of intermediate floor causedCollapse of intermediate floor caused
by battering by adjacent retaining wall.by battering by adjacent retaining wall.
Typical forms of damage in RCTypical forms of damage in RCTypical forms of damage in RCTypical forms of damage in RC
Two deathsTwo deaths

33. Collapse of 'soft storey' groundCollapse of 'soft storey' ground
floor which had insufficient stiffness.floor which had insufficient stiffness.
Typical forms of damage in RCTypical forms of damage in RCTypical forms of damage in RCTypical forms of damage in RC
TotalTotal
compressioncompression
of floorof floor

34. Typical forms of damage in RCTypical forms of damage in RCTypical forms of damage in RCTypical forms of damage in RC
Detachment, fragmentationDetachment, fragmentation
and expulsion of infill walls.and expulsion of infill walls.
Racking
failure

35. Typical forms of damage in URMBTypical forms of damage in URMBTypical forms of damage in URMBTypical forms of damage in URMB
Load-bearing walls disintegrate at angles.Load-bearing walls disintegrate at angles.

36. Typical forms of damage in masonryTypical forms of damage in masonryTypical forms of damage in masonryTypical forms of damage in masonry
Excessively heavy roof in RC: subsides.Excessively heavy roof in RC: subsides.

37. Typical forms of damage in masonryTypical forms of damage in masonryTypical forms of damage in masonryTypical forms of damage in masonry
Detachment of facade elementsDetachment of facade elements
and fall of roof tiles.and fall of roof tiles.

38. People are killed or injuredPeople are killed or injured
because theybecause they lack:lack:
• experienceexperience of earthquakesof earthquakes
• perceptionperception of seismic riskof seismic risk
• adaptabilityadaptability to the risksto the risks
• social discussionsocial discussion of theof the
seismic risk problemseismic risk problem
• wealth accumulation andwealth accumulation and
investmentinvestment in protectionin protection
• training andtraining and practicepractice in dealingin dealing
with earthquake hazardswith earthquake hazards
• socialsocial supportsupport networksnetworks..

39. Unexpected earthquakeUnexpected earthquakeUnexpected earthquakeUnexpected earthquake
MildMild
impactimpact
SevereSevere
impactimpact
CatastrophicCatastrophic
impactimpact
VeryVery
limitedlimited
damagedamage
Fall ofFall of
heavyheavy
objectsobjects
PartialPartial
collapsecollapse
TotalTotal
collapsecollapse
Absolute immobilityAbsolute immobility Frantic egressFrantic egress
UninjuredUninjured
LightlyLightly
injuredinjured
SeriouslySeriously
injuredinjured
KilledKilled

40. Models of typicalModels of typical
vernacular housingvernacular housing
building typesbuilding types
Analysis ofAnalysis of
characteristiccharacteristic
failure modesfailure modes
DeterminationDetermination
of appropriateof appropriate
crisis behaviourcrisis behaviour
Education andEducation and
training oftraining of
householdshouseholds
Culture ofCulture of
protectionprotection
and resilienceand resilience

41. Kang, NW Iran
a mountain village
in a seismic area

42. emergency-planning.blogspot.com
www.slideshare.net/dealexanderwww.slideshare.net/dealexander
D.Alexander@alice.it