Assessing risk and vulnerability

The estimation of probably future losses is a matter of increasing interest to those concerned with development planning in hazard-prone regions. Fundamental to disaster preparedness and mitigation planning is an understanding of what to expect. This needs to be quantified, if only in a crude and approximate way, in terms of the degree of risk faced, the size of event that is likely, and the consequences of an event if it occurs.

The calculation of risk generally needs to consider several types of loss. The most common parameter of loss, and the one most easily dealt with, is economic cost. Cost is widely used because many types of loss can be converted into economic cost. Effects which are considered in terms of economic costs are known as tangible losses. But there are a range of other effects resulting from disasters which are important but which cannot be converted into a monetary equivalent, and these are referred to as intangible losses.

A full consideration of risk would include a complete range of effects, both tangible and intangible, and of several qualitatively different types. The range of undesirable consequences of natural hazards what we might consider as loss parameters are listed in Table 1.

Table 1 Loss parameters for risk analysis