Australian Plate in the context of "Tonga-Kermadec Ridge"

The Lau–Colville Ridge is an extinct oceanic ridge located on the oceanic Australian Plate in the south-west Pacific Ocean extending about 2,700 km (1,700 mi) from the south east of Fiji to the continental shelf margin of the North Island of New Zealand. It was an historic subduction boundary between the Australian Plate and the Pacific Plate and has important tectonic relationships to its east where very active spreading and subduction processes exist today. It is now the inactive part of an eastward-migrating, 100 million year old Lau-Tonga-Havre-Kermadec arc/back-arc system or complex and is important in understanding submarine arc volcanism because of these relationships. To its west is the South Fiji Basin whose northern bedrock is Oligocene in origin.

Macquarie Island is a subantarctic island in the south-western Pacific Ocean, about halfway between New Zealand and Antarctica. It has been governed as a part of Tasmania, Australia, since 1880. It became a Tasmanian State Reserve in 1978 and was inscribed as a UNESCO World Heritage Site in 1997.

Macquarie Island is an exposed portion of the Macquarie Ridge and is located where the Australian Plate meets the Pacific Plate.

The Havre Trough (Havre Basin) is a currently actively rifting back-arc basin about 100 km (62 mi) to 120 km (75 mi) wide, between the Australian Plate and Kermadec microplate. The trough extends northward from New Zealand's offshore Taupō Volcanic Zone commencing at Zealandia's continental shelf margin and continuing as a tectonic feature, as the Lau Basin which currently contains active seafloor spreading centers. Its eastern margin is defined by the Kermadec Ridge created by Pacific Plate subduction under the Kermadec microplate, while the western margin is the remnant Lau-Colville Ridge.