Dynamic Site Characterisation and Site Response in Auckland, New Zealand
The Auckland region has been targeted by local government to accommodate a large portion of the city’s future urban and commercial expansion. The area has highly variable geology; in terms of dynamic site characterisation, the areas with thick organic soil, alluvium, and where basalt has been deposited over soft soils provide particularly challenging characteristics. Auckland is assumed to have a low seismic hazard because of its tectonic setting away from plate margins and major known fault systems. Seismic sources with potential to cause significant shaking in Auckland are associated with the Hikurangi Subduction zone and the Taupo Volcanic Zone. Nearby seismic sources (E.g. Wairoa North Fault, 60 km away) have low activity rates, thus pose less of a hazard. There is also potential for a significant earthquake along an unidentified or off-shore fault, as there may also be large faults in close vicinity to the city whose seismic potential are unknown. The initial stages of this research involved geotechnical and geophysical field investigations to characterise the shear wave velocity (Vs) of the dominant surficial deposits in the Manukau Lowlands region of Auckland (Figure 1). This poster provides an overview of the typical deposits in this region and the surface wave testing methodology.