Development of a regional [formula omitted] model and typical Vs profiles for Christchurch, New Zealand from CPT data and region-specific CPT-Vs correlation

Abstract

A high-resolution near-surface shear wave velocity (Vs) model is developed for the Christchurch, New Zealand region through the application of a recently developed Christchurch-specific empirical correlation between soil Vs and cone penetration test (CPT) data [1,2] to the large, high-spatial-density CPT database [3] available for the Christchurch region. A regional model of time-averaged 30m soil shear wave velocity (Vs30) is developed from this surficial Vs model with consideration for the variable surficial geology and underlying non-CPT-penetrable shallow stratigraphy of the region. Typical Vs and soil behaviour type index profiles are also developed from the CPT-Vs data found within a series of subregions located throughout Christchurch to supplement the general regional characterization provided by the Vs30 model with more detailed and locally relevant descriptions of the soil and velocity profiles typical to the chosen subregions. The high spatial density and extent of the Vs model enable it to be used for both general site classification and site-specific understanding of surficial site effects, the applications of which are examined further in the companion work of McGann et al. [4].