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Overview


The Macquarie Triple Junction is a geological tectonic boundary located at -61.5°N, 161°W at which the Indo-Australian Plate, Pacific Plate, and Antarctic Plate collide and interact. This tectonic boundary is known as a triple junction due to the contact of three individual tectonic plates at one specific location.The Macquarie Triple Junction is located on the seafloor of the southern region of the Pacific Ocean, just south of New Zealand. This tectonic boundary was named in respect to the nearby Macquarie Island, located southeast of New Zealand.

Indo-Australian Plate and Antarctic Plate Boundary
The Indo-Australian Plate and Antarctic Plate Boundary is an active divergent boundary known as the Southeast Indian Ridge(SEIR), which ranges approximately 2000 kilometers at the bottom of the southern region of the Indian Ocean. The SEIR has a complex driving force which is due to the interaction of the Amsterdamn-St. Paul Plateau, a developed hot spot in the western portion of the SEIR, and the Mid-Oceanic Ridge,(MOR). The Amsterdamn-St. Paul Plateau along with the SEIR produce new oceanic crust further separating the Indo-Australian and Antarctic Plates at a intermediate tectonic rate of 65mm/yr. The Antarctic Plate stays relatively stationary while the Indo-Australian Plate migrates in the northeast direction.

Pacific Plate and Antarctic Plate Boundary
The Pacific-Antarctic Plate Boundary is another active divergent boundary known as the Pacific-Antarctic Ridge(PAR). The Pacific-Antarctic Ridge is the southwest region of the East Pacific Rise, the Mid-Oceanic Ridge located at the base of the Pacific Ocean. The PAR is divergent boundary driven by the interaction of a MOR and a deep mantle plume located in the eastern portion of the East Pacific Rise. The Pacific-Antarctic Plate Boundary is spreading at a fast rate of 10cm/yr, where again the Antarctic Plate is relatively stationary in respect to the adjacent Pacific Plate.

Indo-Australian Plate and Pacific Plate Boundary
The Indo-Australian Plate and Pacific Plate Boundary is the most complex region of the Macquarie Triple Junction due to the unique collision of the two plates creating a primarily convergent boundary split by a region of a transform boundary. The Puysequr Trench is the region the boundary closest to the Macquarie Triple Junction, formed by the subduction of the Indo-Australian plate beneath the Pacific plate. The Puysequr Trench ranges approximately 800 kilometers in length, from the Macquarie Triple Junction to the most southern tip of the New Zealand Islands, where the trench makes contact with the Macquarie Fault Zone. The Macquarie Fault Zone is associated with the Alpine Fault, which is a right-lateral strike-slip transform fault boundary which runs through the majority of the New Zealand's southern island. The Alpine Fault is associated with New Zealand's extremely frequent and intense earthquake history. The last major region of the Indo-Australian Plate and Pacfic Plate Boundary is the Kermadec-Tonga subduction zone at which the Pacific Plate is subducted beneath the Indo-Australian Plate, in opposition of the Puysequr Trench. This convergent boundary has a rate of subduction of approximately 5.5-7.4 cm/yr.