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This paper presents a generalised velocity model construction methodology, its computational implementation, and application in the construction of a New Zealand Velocity Model (NZVM2.0) for use in physics-based broadband ground motion simulation. The methodology utilises multiple datasets spanning different length scales, which is enabled via the use of modular subregions, geologic surfaces, and parametric representations of crustal velocity. A number of efficiency-related workflows to decrease the overall computational construction time are employed, while maintaining the flexibility and extensibility to incorporate additional datasets and refined velocity parameterisations as they become available. The methodology and computational implementation processes are then applied for development of a New Zealand Velocity Model (NZVM2.0) for use in broadband ground motion simulation. The model comprises explicit representations of the Canterbury, Wellington, Nelson-Tasman, Kaikōura, Marlborough, Waiau, Hanmer and Cheviot sedimentary basins embedded within an existing regional travel-time tomography-based velocity model for the shallow crust. [ABSTRACT FROM AUTHOR]

A 3D high-resolution model of the Quaternary geological stratigraphic sequence in the Canterbury, New Zealand region is developed utilising datasets of over 500 high-quality water well logs from a database of 29,985, and over 370 near-surface cone penetration test (CPT) records from a database of 13,670. The model, developed using geostatistical Kriging, represents the complex interbedded regional Quaternary geology by characterising the boundaries between significant interbedded geological formations as 3D surfaces. The model is examined in the form of both geological surface contour maps and vertical cross sections, where the most evident trend identified is the easterly dip caused by the dominant alluvial deposition of terrestrial sediments. The developed 3D interbedded Quaternary stratigraphy model has several applications for hydrologic modelling, earthquake-induced ground motion simulations and seismic site characterisation. For the latter case, the role of the model in constraining surface wave analysis-based shear wave velocity profiling is illustrated. [ABSTRACT FROM AUTHOR]

This paper discusses simulated ground motion intensity, and its underlying modelling assumptions, for great earthquakes on the Alpine Fault. The simulations utilise the latest understanding of wave propagation physics, kinematic earthquake rupture descriptions and the three-dimensional nature of the Earth's crust in the South Island of New Zealand. The effect of hypocentre location is explicitly examined, which is found to lead to significant differences in ground motion intensities (quantified in the form of peak ground velocity, PGV) over the northern half and southwest of the South Island. Comparison with previously adopted empirical ground motion models also illustrates that the simulations, which explicitly model rupture directivity and basin-generated surface waves, lead to notably larger PGV amplitudes than the empirical predictions in the northern half of the South Island and Canterbury. The simulations performed in this paper have been adopted, as one possible ground motion prediction, in the ‘Project AF8’ Civil Defence Emergency Management exercise scenario. The similarity of the modelled ground motion features with those observed in recent worldwide earthquakes as well as similar simulations in other regions, and the notably higher simulated amplitudes than those from empirical predictions, may warrant a re-examination of regional impact assessments for major Alpine Fault earthquakes. [ABSTRACT FROM PUBLISHER]