Risk Wise

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understanding of disaster risks across the AusAID port-

folio and support AusAID to better target disaster risk

reduction and humanitarian response activities. This

project sought to broadly identify the characteristics,

frequency, location and potential consequences of rapid-

onset natural hazards including earthquake, tsunami,

landslide, flood, cyclone, wildfire and volcanic eruptions.

Toward an understanding of risk and impact

Disasters are not the inevitable consequence of natural

hazards. A volcanic eruption on an uninhabited Alaskan

island is unlikely to be a disaster whereas the same erup-

tion in the densely populated Asia-Pacific region may

be catastrophic. In order to transform a natural hazard

into a natural disaster, populations need to be exposed

to the hazard. Furthermore, if we dissect the anatomy

of disasters, we find that the impact of the hazard is typi-

cally determined by inherent vulnerabilities within

populations. For example, a magnitude 6 earthquake in

New Zealand is unlikely to cause mass fatalities due to

strict building codes. Yet the same magnitude earth-

quake may lead to many fatalities in the developing

countries of the Asia-Pacific region as building codes, if

available, may not be enforced. To rewrite a familiar

adage, ‘earthquakes don’t kill people, buildings do’.

Thus the ultimate aim of a natural hazard risk assess-

ment is to move beyond an understanding of the hazard

to a more comprehensive understanding of the risks and

potential impacts of hazards on communities. For

example, rather than simply identifying which provinces

have the highest chance of an earthquake or flood, risk

analysis provides information on how many people

would be left homeless by a 1-in-100-year flood or a

magnitude 6.5 earthquake.

A crucial aspect in the assessment of natural disaster

risk is the metric used to define a past disaster and there-

fore the risk of future disasters. Typically, the number of

fatalities is used to classify a disaster. However, this

simplistic metric ignores the number of injured, home-

less and displaced, the requirement for international

humanitarian assistance and the economic impact of a

disaster. In recognition of this we used ‘significantly

impacted population’ as the risk metric in our study.

This deliberately vague term covers death, injury and

displacement, prolonged loss of access to essential

services and/or shelter, and significant damage to agri-

culture, horticulture and industry. Future work to

improve our understanding of natural hazard risk in the

Asia-Pacific region will need to test more specific risk

metrics, particularly those most useful in an interna-

tional development and humanitarian context. For

example, it may be useful to calculate risk in terms of the

number of fatalities and injured, the extent of building

destruction, the period of compromised access to essen-

tial services (water, electricity, communication, health),

the impact on food supply (would the annual harvest

be destroyed?) and/or the effect on the economy.

A particularly useful risk metric, and one touched on

in our study, is the risk of a government’s disaster

ter. Second, natural disasters, particularly relatively infrequent, high-

magnitude natural disasters (for example, the 2004 Indian Ocean

tsunami), require a significant disaster relief and humanitarian

response from aid agencies, which may shift resources away from

other development objectives. For this reason the Australian Agency

for International Development’s (AusAID) strategic direction affirms

that managing and responding to natural disasters should be central

to development planning.

A recent activity undertaken by Geoscience Australia for AusAID

made a preliminary assessment of natural hazard risk across all Asia-

Pacific partner countries.

The objective was to gain a better

The convergence of high population density and active

faults in Manila, Philippines

Movement on the Marikina Valley fault could have a devastating impact on

Manila, of a scale determined by the earthquake magnitude and epicentre

Source: Population data from Landscan; fault location from Nelson et al. 2000