New Zealand is located on the boundary of two of the world’s major tectonic plates – the Pacific Plate and the Australian Plate, this animation shows how the plates interact.

Full script:
In New Zealand, the Australian and Pacific Plates push against each other along a curving boundary.
How they meet each other changes along this boundary.

At the southern end of the South Island, the Australian Plate dives down below the Pacific Plate.
In the North Island the opposite situation occurs with the Pacific Plate being pushed under by the Australian Plate.

In between, through most of the South Island, the two plates grind past each other along the Alpine Fault.