Spatial correlation of earthquake ground motion and spatial variability of geological characteristics in seismic hazard and risk assessment

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In seismic loss estimation for distributed portfolios and spatially distributed systems (lifelines), the average expected loss and the distribution of loss around the mean are very important for decision making and mitigation activities. Whereas the mean loss is determined by the sum of individual losses, the variance of loss depends on the spatial correlation of earthquake ground motion. Standard hazard assessment and standard ground motion prediction cannot deal with correlation. Derivation of correlation properties of ground motion from observed strong motion data is only possible in very few locations as very high data density is mandatory. The objective of the project is the development of a methodology for earthquake ground motion prediction and its spatial correlation for seismic hazard and seismic loss assessment by introducing a model, which relates spatial correlation of ground motion with spatial variation of geology. Specific item are: 1. Identification of factors relevant for spatial correlation of ground motion using the databases accumulated in Japan and Taiwan and modern ground-motion prediction equations; analysis of spatial variability of geotechnical and geological characteristics using traditional geostatistical technique and advanced copula methods; 2. Establishing of quantitative relationships between parameters of spatial correlation of ground motion and characteristics of spatial variability of geology; development of model(s) that predict correlation properties from geostatistical data of regions; 3. Demonstration of relevance of correlated ground motion for hazard assessment, loss estimation, ground motion modeling and Shakemap generation in areas with a lack of ground motion data and information about correlation structure. The innovation by this project is twofold: (1) We do not know of any systematic work to link correlation of ground motion and variability of geology. (2) Copulas used widely in insurance and financial modeling may prove a powerful tool for earthquake engineering as well.