Session 1.3 - Lifelines

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Lifelines and Earthquakes: A Review of New Zealand's Key Vulnerabilities

D.R. Brunsdon, M.C. Daly and A.J.W. Lamb

Lifelines engineering in New Zealand was initiated in 1989, and is now an established technical discipline. There are now Lifelines Projects and Groups in almost every region of New Zealand. The Lifelines engineering process represents a very effective regional scale collaborative model which is being viewed by other sectors as a model framework for integrating technical processes with community needs.

While the New Zealand Lifelines process addresses all natural hazards, the considerable risks to infrastructure posed by earthquakes throughout the country make it a prime focus of Lifelines work. This paper summarises the findings from Lifelines work to date regarding seismic vulnerability of utility networks. This includes first-hand observations by New Zealand Lifelines Study Tours following major earthquakes during the 1990ís. The common earthquake mitigation measures for the key utility sectors are summarised, and a critical appraisal made as to the level of progress with mitigation in each area. The authorsí views are given as to where the emphasis should be placed for future earthquake mitigation for utilities given the current economic environment.

Paper 146: [Read][Print]

Keywords: earthquake, mitigation, response preparedness, lifelines

Natural Hazards Risk Associated with Petroleum Storage, Wellington Region, New Zealand

P. Brabhaharan, G.K. Bharathy, D. Prentice and R. Lynch

Wellington Regional Council has a strategy to identify, assess and manage the risks from natural and technological hazards. As part of this strategy a study was carried out to assess the risks associated with petroleum storage from natural hazards. The predominant hazard posing a risk to petroleum storage facilities in the Wellington Region is earthquakes. The assessment included bulk petroleum storage facilities, storage at service stations as well as pipelines.

This case study illustrates the assessment of the risk associated with spill and fire / explosion events at petroleum storage facilities, due to natural hazards, using techniques such as event and fault tree analyses. The vulnerability of the tanks was assessed based on their age, condition, design characteristics and the earthquake hazards. The earthquake hazards included ground shaking, liquefaction and slope failures, and other natural hazards comprised wild fire, flooding and storm induced landslides.

The effect of petroleum spills or fire / explosion were assessed considering the people, built and natural environments. The risks to these environments were assessed as a combination of the hazard and the vulnerability of these environments to the consequences. The spatial risk was derived using a geographical information system.

Risk management measures were identified to manage the risks from the hazards associated with petroleum storage.

Paper 087: [Read][Print]

Keywords: petroleum, risk, natural hazards, earthquake, wellington, risk management

Modelling the Spread of Post-earthquake Fire

W.J. Cousins, G.C. Thomas, D.W. Heron, S. Mazzoni and D. Lloydd

Post-earthquake fire is a highly variable phenomenon. Fire losses are often zero, but sometimes conflagration can develop with near total destruction of a city. We describe two GIS-based ways of modelling post-earthquake fire in the urban setting, one static and one dynamic. The static approach relies on a buffering technique to define "burn-zones" that are sampled randomly to give estimates of losses. From repeated sampling we are able to model the fire-loss as a function of numbers of ignitions, building separations and building properties. The dynamic approach uses a cellular automaton technique for determining both the rate and extent of fire spread in response to a wide range of factors including wind, radiation, sparking, branding, cladding materials and individual separations of buildings. Using the static model we show that losses due to fire following a major earthquake near Wellington City are likely to be smaller than losses due to shaking, provided the wind at the time is no stronger than a moderate breeze, but are likely to become severe in gale-strength winds. Creating artificial firebreaks appears not as effective a mitigation measure as minimising the numbers of ignitions and providing buildings with non-flammable claddings.

Paper 001: [Read][Print]

Keywords: fire, earthquakes, urban fire spread, fire following earthquake, loss modelling

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