Most of the north portion of the indo-australian plate is a what boundary.

Convergent boundary

Explanation:

Most of the northern part of the Australian Plate or the Indo-Australian plate is moving to the north and colliding with the Pacific Plate and the Eurasian Plate.  

Because the boundaries with these plates are convergent boundaries, they are zones of volcanic activity and formation of island arches such as the Indonesian islands. This collision is the result of the collision of two equally dense oceanic crust plates. This is mostly the case with the Pacific Plate. Since the Eurasian Plate is a continental crust plate, the Australian Plate is currently subducting under the Eurasian Plate because the Eurasian Plate is less dense than the Australian.

The Indian Plate is considered to be its own subplate since its slower movement is causing a separation from the Australian plate. The difference is due mainly to the type of convergence with the Indian Plate facing the Himalaya Mountains.

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