SYSTEMIC UNCERTAINTIES AND DECISION SUPPORT APPLICATIONS IN REGIONAL SEISMIC LOSS ANALYSES
A number of tools and advancements have been developed over the course of the last decade for public use in regional seismic disaster planning. This paper addresses some of the considerations and approaches that influence state-of-theart regional seismic loss assessments and risk management, with particular emphasis on approaches applied to areas having potentially high consequence but low probability seismic hazards in the United States. The various components of regional seismic loss assessment are synthesized within a GIS-based framework, including the aggregation and propagation of uncertainties inherent in the analysis. The threat posed by ground shaking and ground failure hazard effects is estimated and mapped onto high resolution point-wise building stock and bridge inventory assets. Inventory vulnerability is assigned based on structural classifications of construction materials, together with general system configurations and lateral resisting system types. Likelihood of damage to the built environment is then determined by the combination of the hazard and vulnerability for each building and bridge, and social and economic consequences are projected based on correlation with descriptions of physical damage levels, both in terms of expected values, and dispersions of the aggregate regional analysis output. Decision support algorithms are also discussed, which leverage the high resolution of the regional analysis output to focus mitigation planning and capital investment on particularly sensitive and influential assets within study regions.
EARTHQUAKE LOSS ESTIMATION AND MITIGATION IN EUROPE : A REVIEW AND COMPARISON OF ALTERNATIVE APPROACHES
The paper contributes to an assessment of the uncertainties involved in the use of current loss modeling methodologies when applied to the estimation of building damage and casualty generation in urban areas. The work derives from studies conducted within the EU-funded LESSLOSS project with the aim of providing a basis for urban planning authorities methods to assess alternative mitigation strategies. Research teams in Istanbul, Thessaloniki and Lisbon developed methods applicable to their own city and building stock. A benchmarking study was then carried out to compare the results of the three approaches when applied to a standardized “urban block”. The paper, presents the results of the benchmarking study, and reviews the differences between the loss estimation approaches used, There are significant differences in surface ground motion, and even greater differences in predicted damage and casualties resulting from the ground motions using the different approaches. The paper discusses possible reasons for these differences and the implications for the estimation of uncertainty in urban loss estimation.
A comparison of seismic risk maps for Italy
National seismic risk maps are an important risk mitigation tool as they can be used for the prioritization of regions within a country where retrofitting of the building stock or other risk mitigation measures should take place. The production of a seismic risk map involves the convolution of seismic hazard data, vulnerability predictions for the building stock and exposure data. The seismic risk maps produced in Italy over the past 10 years are compared in this paper with recent proposals for seismic risk maps based on state-of-the-art seismic hazard data and mechanics-based vulnerability assessment procedures. The aim of the paper is to open the discussion for the way in which future seismic risk maps could be produced, making use of the most up-to-date information in the fields of seismic hazard evaluation and vulnerability assessment.