Regional Seismic Hazard and Risk Analysis through Geographic Information Systems

A geographic information system (GIS) provides the ideal environment for conducting a comprehensive regional seismic hazard and risk analysis. A GIS has the ability to store, manipulate, analyze, and display the large amount of required spatial and tabular data The system can typically be linked to external computational programs, high level database management systems, and knowledge-based expert systems. The objective of this research is the development of a methodology for using geographic information system technology to conduct a regional multi-hazard seismic risk analysis. The term multi-hazard refers to the consideration of ground shaking and the secondary site effects of soil amplification, liquefaction, landslide, and surface fault rupture. The methodology involves a modular framework that allows new models and database information to be included as the technology advances.

This dissertation describes in detail the current GIS technology and the various steps in a regional seismic hazard and risk analysis. An overview of the different models for estimating the effects of local site conditions is presented. This research includes the development and example illustration of a GIS-based methodology for quantifying and combining the hazards associated with these secondary site effects. The methodology to combine the various hazards is based on a weighted average approach that utilizes the knowledge of local experts. This dissertation also covers the estimation of regional earthquake damage and loss, including the development of a methodology for compiling a comprehensive inventory of structures in a large region.

A substantial part of this dissertation is devoted to a case study that illustrates the ideas and methodologies developed in this research. The case study is an earthquake damage and loss study for a magnitude 7.5 event on the Wasatch fault in Salt Lake County, Utah. The various seismic hazards are quantified and integrated, and a structural inventory of nearly 195,000 buildings is compiled. Numerous maps and tables of inventory data and results are included to help prove the effectiveness of the GIS for conducting a large regional earthquake hazard and risk analysis. The final loss estimates appear to be reasonable when compared to recent large earthquakes in metropolitan areas.