Table 1 Definition of terms used in the Auckland Engineering Lifelines Project 1996–1999 (modified after Daly and Wilkie 1999 )

Damage

Physical harm impairing the operation of a system, network or node caused by an event.

Event

The hypothetical occurrence of any of the natural disasters considered. An incident or situation which occurs in a particular place during a particular time interval (Australian/New Zealand Risk Management Standard 4360:1999).

Hazard

The future occurrence or risk of occurrence of any of the natural disasters considered. The source of potential harm or a situation with a potential to cause loss.

Impact

The time - related effect of damage, comprising:

Node impact - the reduction in operational performance and function of a damaged node.

Network impact - the time and spatial reduction in function of the utility network caused by the cumulative node impacts.

System impact - the reduction in function of the combined network impact on the whole utility system.

Regional impact - The cumulative effect of the system impact and other non-utility effects on the region.

Regional system

The integrated and interrelated social, commercial, cultural, political, legal and natural environment of the region.

Scenario analysis

Defining a particular scenario to enable the impact of a specific event on the entire utility system to be assessed.

Uniform hazard analysis

Defining a given hazard enables mitigation measures for each utility to be rapidly identified.

Utility network

An interconnected set of utility components and links for providing a utility service.

Utility node

A discrete constituent of the utility network.

Utility system

The combined utility networks, their interdependencies and the interrelations for providing infrastructure services.

Vulnerability

The extent to which a system, network or node is sensitive to damage from an event.