L'Aquila Earthquake

Self-protective behaviour during earthquakes: some lessons from

L'Aquila, 6 April 2009

David Alexander University College London

Analysis

• registered • archived • forgotten • ignored

Vulnerability maintained -

• utilised • adopted • learned

Disaster risk reduced

+

Lessons Past

events

The process of disaster risk reduction (DRR)

But what lessons? Let's go and see...

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.

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

A bracketed duration of 50 seconds would have caused thousands of deaths.

Deaths: 308 Injuries: 1,500 (202 serious, & 898 triaged) Homeless people: 67,500 Tent camps: 171 Tents: 5,700 (for 8 people each)

L'Aquila:- • a university city • population 72,800 • 14 outlying villages

Municipalities reporting damage:- • 49 in the government decree • 96 in total • 81 in Abruzzo Region • 16 seriously damaged.

Opi-Pescasseroli 1984 Avezzano 1915 • 32,000 deaths • 10,700 of them in Avezzano city (pop. 11,400)

Other earthquakes in Abruzzo:

Deaths in the L'Aquila 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.

• 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 L'Aquila earthquake:-

How aggregate behaviour factors altered the distribution of injuries:-

Negative: presence of many university students in sub-standard accommodation.

Positive: earthquake occurred at the end of the weekend - many people had not returned home (and they never would!).

24 km

11 k

m

Distribution of deaths in the L'Aquila earthquake of 6/4/09

L'Aquila

Onna

Earthquake of 6 April 2009 at L'Aquila: Mortality by age-group and sex

(n=308)

(n=202)

6-25 deaths 3-5 deaths 1-2 deaths

Clusters of multiple

deaths

n=202

L'Aquila city

One or two individuals

No deaths

• one fifth to one quarter of deaths occurred in only seven buildings

• deaths were clustered in areas of topographic amplification and poor quality buildings

• the location of deaths corresponds closely with partial and total building collapse.

Distribution of deaths in L'Aquila centre

• apart from student housing, death clusters were not particularly differentiated by age group

What if the earthquake had occurred at another time of day?

When people would have been in church:- • serious damage to religious buildings

A working day during business hours:- • very serious damage to public buildings • much masonry fell into narrow streets • many vehicles were crushed • serious damage to L'Aquila hospital.

L'Aquila Prefecture: identified to be at high seismic risk in a report

dated June 2008.

Incipient collapse of intermediate floors caused by lack of stiffness in structure.

Column breakage

Typical forms of damage in RC

Collapse of intermediate floor caused by battering by adjacent retaining wall.


Two deaths

Collapse of 'soft storey' ground floor which had insufficient stiffness.



Detachment, fragmentation and expulsion of infill walls.

Racking failure

Typical forms of damage in URMB

Load-bearing walls disintegrate at angles.


Excessively heavy roof in RC: subsides.


Detachment of facade elements and fall of roof tiles.

Preparedness is thwarted by:-

• lack of experience and direct contact with the problem • lack of adaptability and inadequate perception of the need to adapt • insufficient perception to stimulate a person to take action • social: lack of communication and sharing of the problem • economic: failure to accumulate wealth and failure to invest in protection • organisation: lack of a facilitating social structure and incentives.

Ten reasons not to run outside during 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.

Eight reasons for not remaining in 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.

Douglas Copp's 'triangle of life' would not have worked in L'Aquila.

Neither would sheltering under a table. Probably the best response would have

been to retreat further into the building.

Seek place of refuge

Remain in situ

Seek potential cavity Rush

outside

Unexpected earthquake

Mild impact

Severe impact

Catastrophic impact

Very limited damage

Fall of heavy objects

Partial collapse

Total collapse

Absolute immobility Frantic egress

Uninjured Lightly injured

Seriously injured

Killed

A scale for damage and personal risk level

Damage level: [1] minimum damage to walls, fitments and furniture. Personal risk level: prudent behaviour will minimise risks.

Damage level: [2] significant damage to structures, cladding and fitments. Personal risk level: significant risk of injury but not of death.


Damage level: [3] general damage and collapse of architectural elements. Personal risk level: significant risk of injury but relatively low risk of death.


Damage level: [4] serious damage or partial collapse of building. Personal risk level: strong risk of injury and significant risk of death.


Damage level: [5] collapse of more than 50% of the structure. Personal risk level: limited and mainly unpredictable probability of survival.


Poor building quality

(low seismic resistance)

Proximity to epicentre and fault rupture

Topographic amplification

Sedimentary amplification

Q E

T S

Concentration of casualties

C

C = f { E,Q,S,T }

Deaths

Injuries

Q E

T S

A possible survival strategy

Identify 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 that they will batter down the building • use of heterogeneous materials giving rise to a complex seismic response.

• avoid risky behaviour • create an exit strategy • identify a safe place to reach near to the house • identify the most dangerous parts of the house and how to avoid them • create a mutual support network of friends, relatives and neighbours • collect and store useful equipment • train family members and test your reaction plan.

A possible survival strategy

Thank you very much

for listening.

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Education

L'Aquila Earthquake