is a major tectonic plate
that includes the continent of Australia
and surrounding ocean
, and extends northwest to include the
and adjacent waters. It was formed by the fusion of Indian and Australian plates 43 million years ago.
Recent studies, and seismic events such as the 2012 Indian Ocean earthquake
, suggest that the Indo-Australian Plate may be in the process of breaking up into two separate plates due primarily to stresses induced by the collision of the Indo-Australian Plate with Eurasia along the
The eastern part (Australia) is moving northward at the rate of 5.6 cm per year while the western part (India) is moving only at the rate of 3.7 cm per year due to the impediment of the Himalayas. This differential movement is resulting in the compression of the plate near its center at Sumatra and a potential division into the Indian and Australian Plates.
The two protoplates or subplates are generally referred to as the Indian Plate
and the Australian Plate
may also be separating off of the west side of the Indian subplate.
in Australia confirms the plate’s velocity of 67 mm/yr at 35 degrees east of north. Note also the same directions and velocities for points at Auckland
and southern India. A slight difference in local direction at Auckland is presumed due to a slight buckling of the plate there, where it is being compressed by the Pacific Plate
South of New Zealand the boundary becomes a transitional transform-convergent boundary, the
Macquarie Fault Zone
, where the Australian Plate is beginning to subduct under the Pacific Plate along the
. Extending southwest of this trench is the