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The performance of an urban electric utility distribution system was evaluated for the February 2001 Nisqually earthquake. The restoration rate of the lifeline following the event was determined; the distribution of outage durations was estimated; and correlations between lifeline damage and instrumental Modified Mercalli intensity, peak ground velocity, and peak ground acceleration values were ascertained using a GIS (geographical information systems) approach. Using a logit regression analysis, a fragility curve was developed for the lifeline in a manner similar to O'Rourke's formulation of water-line performance (O'Rourke et. al. 2000). Extrapolation of the model to the Seattle Fault earthquake scenario was made to demonstrate its feasibility for prediction.

Local policies can play an important role in establishing a context that shapes vulnerability and influences subsequent recovery of lifelines under the natural hazards of extreme wind and seismic events. External factors, such as access availability, have long been known to influence the rate of restoration of utility systems following blackouts. Thus, since system performance takes place within a socio-technical-political context, it can be anticipated that selected local policies may also influence either the geographic extent of damage or the rate of restoration or both. This project empirically validates the assumption that selected local non-design policies establish a context that significantly (measurably) influences system functionality in terms of spatial extent and duration of outage.

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