Indo-Australian Plate: Tectonic Boundaries and Movement

Indo-Australian Plate Tectonics

The Indo-Australian Plate is one of Earth’s 7 major plate tectonic boundaries. It’s the second smallest being slightly larger than the South American Plate.

By the name, you can probably identify that it contains parts of India and Australia. But as with most tectonic plate boundaries, they often consist of both continent and ocean crust.

The Indo-Australian Plate includes the majority of the Indian Ocean. It borders the Eurasian Plate in the north, the Antarctic Plate in the south and the Pacific Plate in the east.

Continental drift means that plates are never idle. Over time, they move at a snails pace. For example, the Indo-Australian Plate moves at an average rate of about 3 centimeters per year.

Two plates separated but we often count them as one

Indo-Australian Plate

The Indo-Australia plate is a major plate combining the Australian and Indian Plate. But they are widely considered to be two separate plates.

The Indo-Australia plate stretches from Australia to India. It also includes the oceanic crust from the Indian Ocean. The north-east side of the Australian plate converges with the Pacific Plate.

Long ago, Australia, India and Antarctica were once connected as the supercontinent Gondwana. As part of the supercontinental cycle, India drifted apart moving northwards.

At about 58,900,000 km2, the Indo-Australia plate is the sixth largest plate tectonic boundary.

The Himalayan mountain range formation

About 50 million years ago, the Indian Plate and Eurasian Plate began colliding into each other lifting the Himalayan mountain range. To this day, these convergent plate boundaries are still uplifting building new mountain.

Because plate tectonic boundaries contain both oceanic and continental crust, the Indo-Australia plate contains the following features:

  • Both countries of India and Australia are situated on the Indo-Australia plate.
  • Sri Lanka, Fiji, Vanuatu and parts of New Zealand, Pakistan and Papua New Guinea are located on this plate
  • The Indo-Australia plate contains majority of the Indian Ocean and Tasman Sea between Australia and New Zealand

The Australian Plate pushes into the Pacific Plate along the country of the New Zealand causing violent earthquakes. For example, the magnitude 8.2 Wairarapa earthquake struck New Zealand in 1855 and was largest recorded in New Zealand’s history.

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