Mortality Patterns in Earthquakes: the Example of L'Aquila, 6 April 2009

David Alexander University College London

"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

Towards an evidence-based approach to earthquake epidemiology

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.

The earthquake

Deaths: 308 Injuries: 1,500 (202 serious, & 898 triaged) Homeless people: 67,000 Tent camps: 171 Tents: 5,700 (for 8 people each)

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:-

Fatal injuries

All injuries

Serious injuries

low ratio

low ratio

high ratio

After more than 30 years of study, the relationship between injury and

damage patterns is still poorly understood.

Characterising damage

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.

Typical forms of damage in RC

Two deaths

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

Typical forms of damage in RC

Compressed ground floor

Typical forms of damage in RC

Detachment, fragmentation and expulsion of infill walls.

Racking failure

Typical forms of damage in URM

Load-bearing walls disintegrate at angles.

Typical forms of damage in URM

Excessively heavy roof in RC: subsides.

Mid-floor damage to multi-occupancy bldg:

Intertia effect

Basal acceleration

Interaction = damage

Lack of stiffness in frame

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

Detachment of façade elements and fall of roof tiles.

Algeria 2003 L'Aquila 2009

Stairwell collapse

Poor quality building

(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

How, where and why

people died; who they were;

how they reacted to

the earthquake

Self-protective behaviour

Hospital mass-casualty

response

Urban search and rescue (USAR)

A practical earthquake epidemiology

Focus Potential benefit to...

Active behaviour: • journey to and from work • recreational activities, etc. • family life at home

Passive behaviour: • sleeping at night • role, efficiency and rapidity of search and rescue and medical assistance after the earthquake.

Behavioural influence on casualties

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.

0.5 1 3 12 1 2 3 45 7 10 15 Hours Days

Survival time

100

50

0

Perc

ent

age

of

peop

le t

rapp

ed a

live

un

der

the r

ubble o

f co

llaps

ed b

uildings

Critica

l pe

riod

Source: Coburn and Spence (2002)

These are the people

who died in the

6th April 2009

L'Aquila (central Italy)

earthquake

Poggio

di Roio

L'Aquila

Province

Abruzzo Region

San

Gregorio Onna

Poggio

Picenze

Villa

Sant'Angelo

Tempera

Paganica

San Pio

delle Camere

Fossa

Pianola

San Demetrio

ne' Vestini

L'Aquila

Roio

Piano

Tornimparte

Bazzano

Bagno

Lucoli

Preturo

10 km

Epicentre

202

39

17

8

8 5

5

5

4 3

2 2

2

1

1

1

1

1

1

Location of deaths (by town), n=308

0 50 100 150 200

L'Aquila

Villa Sant'Angelo

Tempera

Poggio Picenze

Fossa

Pianola

Tornimparte

Civita di Bagno

Poggio di Roio

Sant'Angelo di Bagno

Deaths

Null hypothesis: no factors of age or gender increased the probability of being killed in the earthquake.

51.1

60.6

57.5

60.6

66.5 56.8

22.8

61.6

56.0 26.0

69.5 66.5

83.0

74.0

8.0

26.0

57.0

73.0

77.0

Average Age of Victims (by town), n=308

52.7

L'Aquila City: location of deaths of 30-39-yr olds

Male

Female

6

1 Total collapse of house, single death: 3F

2 Collapse of house kills entire family: 6F/2M

3 Total collapse of house: slow death: 1F

4 Partial collapse of house: 2M

5 Crushed by beam: 1F

6 Not known: 1F

2 2

2

2

2

2

2

2

1

1 1

3

4

4

5

Area of

comparatively

light damage

and no

casualties

Area of sporadic

damage and

few casualties

Area of

topographic

amplification,

with major

damage and

casualties

Area of roof and

stairwell collapse:

limited casualties

500 m

Male

Female

All victims in

L'Aquila city

centre area

n=186

To NE:

unreinforced

masonry

buildings

To SW:

reinforced

concrete

buildings

Topographic

amplification

Roof and

stairwell collapse

Sporadic

damage

Light damage

(no deaths)

Pensioners'

disaster area

Students'

disaster area

Older people were more aware of the danger but less willing or able to react to it.

Females, especially old ladies, were more inclined to passive behaviour.

Males, especially old men, were more inclined to try to get out of the building.

Old people were more inclined to behave passively.

• 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?.

Implications

Conclusions

• men and women were doing different things when quake struck

• 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.

Disproved hypotheses:-

• clustering of male and female deaths

In the L'Aquila 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 excess over the demographic predictor:- • Women: 40 (13% of total mortality) • Men: 19 (6.2% of total mortality).

"More research is needed"

David.Alexander@ucl.ac.uk emergency-planning.blogspot.com www.slideshare.net/dealexander

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