Abstract

While site response phenomena are well recognized globally, the influence of regolith properties on ground motion has not previously been investigated for much of Australia. In an effort to characterize the regolith in terms of its ability to modify earthquake ground shaking, this validation study assesses the national site classification map of Australia, which has been developed for application in first‐order earthquake hazard and risk assessment. In the absence of regolith thickness and fundamental period data, site classes are assigned based on a method developed in California that uses the relationship between geological material and the shear‐wave velocity of the upper 30 m (VS30). The classification scheme is then adjusted to suit the Australian geological environment, including a correction for the presence of weathered in situ regolith commonly encountered in this stable tectonic setting. The results are validated using geophysical and geotechnical data from a variety of Quaternary sedimentary environments in the Newcastle, Sydney, and Perth urban areas, and from bedrock‐dominated environments at a range of sites across Australia. The results of these analyses demonstrate the utility, but also highlight the limitations, of applying a depth‐limited shear‐wave velocity method in site classification for seismic hazard assessment.

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