Abstract

Determining how crustal structure developed in previous tectonic regimes influences current deformation is important for understanding seismogenic behaviour.  Paleozoic-Mesozoic convergent-margin tectonics produced the southeastern South Island crust, which is currently involved in late Cenozoic transpressional collision. We examine crustal velocity structure through joint inversion of earthquake travel times and ambient noise derived group velocities to increase the resolution of Vp (P-wave velocity) and Vp/Vs across the region. This method improves the details of the shallow velocity structure and highlights lithological properties, uplifted regions and distributed fracture zones. The complex velocity structure, integrated with late Cenozoic faults, structural domains, seismicity patterns and geodynamic modelling, shows how Cenozoic structures relate to deeper properties.