Evaluating the Post-Earthquake Accessibility of Hospitals for Mitigation Strategy Decision Support By Fragility and Connectivity Modelling

Abstract eng:
The aim of this paper is to present a trivial proof of concept for analysing the impact of post-earthquake damage to lifelines on indicators of social resilience. The conceptual methodology is demonstrated by carrying out a GIS-based analysis of the impact of damage to highways bridges on accessibility to emergency healthcare facilities in the Santa Clarita suburb ofLos Angeles. A magnitude 6.9 earthquake from the Santa Susana fault zone was used as a scenario event with bridge damage predicted using the HAZUS methodology to calculate exceedance probabilities and uniform random sampling to assign damage states. Moderate damage state was used as the threshold for bridge closure. The system performance was measured as the mean travel time between neighbourhoods and the local hospital, weighted to account for population. The distribution of delay amongst the population has also been derived. The analysis was repeated for three further scenarios to identify the critical node for prioritisation of mitigation works by comparing the impacts with the post-earthquake scenario. The analysis was based on the Los Angeles County disaster route network with straight-line approximations for travel distance on local roads. Results were compared to those obtained using the actual path distance on local roads and this showed that interpretation of the results could vary depending on the measurement method and the decision variable used. Therefore straight-line distance is not a safe approximation. The methodology proposed here will be expanded in the future for a more detailed study assessing the riskfrom damage to multiple lifelines and using a wider range of indicators.

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