Keywords: seismic loss assessment, geographical information system, function modules, vulnerability simulation, scenario, flowchart control panel.

A Seismic Loss Assessment System has been developed based on a Geographic Information System (GIS). This GIS-based program package, developed using VC++ and ArcView Avenue, is designed for application in urban areas located in low-to-moderate seismic regions, such as Hong Kong. An important component of the system is the information database that contains regional geo-data, urban geographic information (buildings, traffic/lifeline systems), as well as economic/demographic statistical data.

The subsystems for loss assessment and emergency management are integrated in the form of function modules: SHA (seismic hazard analysis), Structural Vulnerability Simulation, and Economic and Social Loss Estimation. The modules are based on recognition formulas and developed for local adaptation. The reliability of the output results is improved by adoption of seismological modelling of ground motion attenuation. Logic tree, fuzzy interpolation and case studies have been completed, which make the decision system widely applicable for urban planning / developing / emergency management, as well as international insurance and reinsurance evaluations.

Employing GIS tools for spatial analysis and network analysis, the system provides rapid estimation of physical damage and informative assessment of economic/social loss. Furthermore, the system can generate visualized simulations for seismic design demand levels. Another advanced feature of the system is the introduction of seismic scenarios. As the trigger of loss assessment, seismic demands in this system are hence not limited to probabilistic analysis. Multiform ways are designed for determining the scenario (including entering M+R values, clicking a location on the digital maps or selecting from historical catalogues). With fuzzy interpolation technique, the SHA module generates probabilistic analysis for the user-input scenario to evaluate its recurrence rate or return period. Seismic demands of four typical earthquake scenarios and three exceedance probability levels (2%, 10%, 50% in 50 years) have been stored as default inputs.

The manipulation interface has been designed to be user friendly. In addition to conventional menu/tool bars, a control panel has been designed and added to the main frame, as an alternative operation engine. This control panel appears as a flowchart. Interactive relations between modules/tasks are clearly shown on the panel. Of special note is that every node in the 'flowchart' is actually a control icon that is hot-linked to the corresponding calculation steps. Users can run the system step-by-step from the start, or run selected steps, by clicking directly on the icons at the corresponding nodes of the flowchart. The clusters indicating the activated steps are highlighted on the flowchart, to enable users to track the current processing stage of the system.

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