Isointensity-isoexposure concept for seismic vulnerability analysis — A case study of the 1999 Chi-Chi, Taiwan earthquake

Fragility curves can be developed using analytical or empirical methods. When the actual building damage records and the associated ground motion data are available, empirical methods are often adopted. Traditionally, district-based records of building damage are analyzed for developing such fragility curves. In this paper, a new procedure based on the concept of “isointensity-isoexposure” is developed. The new procedure is demonstrated through a case study of the building damage records collected from the 1999 Chi-Chi, Taiwan earthquake. The results show that the fragility curves developed with the proposed procedure are more in-line with observations than with the traditional district-based procedure. The developed fragility model may be used for earthquake loss estimation and future emergency planning in the study area. The limitations of the proposed approach include: (1) the developed fragility curves are area-specific and may not be readily applicable to other regions, and (2) ground motion intensity data may not be available at every location in an area of interest.