Regional Tectonics and Hazards
Onshore New Zealand provides much of the evidence for deformation over the last 20 million years (e.g. faulting, volcanoes) associated with the plate boundary that bisects the country. In contrast, the offshore continental area east of New Zealand, less deformed by this recent activity, is probably the best region for understanding New Zealand's history between 150 and 80 million years ago. This is the period when New Zealand was part of the Gondwana supercontinent before splitting apart from Australia and Antarctica.
GNS Science has long realised that the seafloor being subducted beneath the North Island, back into the earth's mantle, was unusually thick and buoyant. This buoyancy affects the uplift of the North Island above sea-level as well as the generation of earthquakes and volcanoes. Marine surveys by GNS Science staff over the last 20 years have revealed the extent and structure of this triangular Hikurangi Plateau Large Igneous Province.