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Exposure as an indicator of risk

Clearly it is not just hazard that results in disaster, if there is nothing of value to be lost in the area affected then the hazard is not a threat.

Exposure is the situation of people, infrastructure, housing, production capacities and other tangible human assets located in hazard-prone areas (UNISDR 2017).

It is one of the defining components of disaster risk with elements within an area of an event are exposed to the hazard leading to the disaster.

Evidence suggests that in the most extreme or very large magnitude events in particular earthquakes and tsunamis, exposure, in the form of settlement density or the number of physical structures or assets in the path of the hazard, is the best indicator of risk and impact. (UNISDR, 2015)

However, for the majority of threats the simple measure of structures in the built environment exposed is unlikely to adequately represent the degree of risk posed.

Events such as droughts, epidemics or pest infestations will have little or no damage to infrastructure but their cost in direct and indirect terms could be devastating.

Reporting risk on the basis of structural exposure which is translated into risk of economic loss tends to significantly underestimate the disaster risk posed in less economically developed contexts.

An alternative approach is to measure exposure using population density. However, population data maybe somewhat unreliable for a number of reasons.

Your task

What are the causes of uncertainty in measuring structural exposure and population based exposure, is there a better mechanism?

In your opinion is exposure to disaster risk increasing and if so why?

Further reading

You may find it useful to read the following web article:

Prevention Web (2015) Intensive and Extensive Risk [online] available from https://www.preventionweb.net/risk/intensive-extensive-risk [10 December 2019]

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This article is from the free online course:

Disaster Risk Reduction: An Introduction

Coventry University