These two blogs
stimulated me to produce a 3D model simulating Indo-Australian plate movement, which, i hope, will help to visualize it better.
Here is Indo-Australian plate, shown tipping at India side (blue) and rising on NZ side (red)
A plate tipping on one side would have an axis (pivot) of rotation in its horizontal plane.
Now, imagine Indo-Australian plate to be a giant rectangle of irregular shape - it is tipping on its diagonally opposite sides.
What i am trying to relate is that this plate tips in a complicated 3-dimensional way: its Indian edge generally lowers, while also tipping sideways a bit.
Imagine that you hold a rectangle with two hands at opposite corners (black lines) and you can rotate it along its axis, with two other corners turning up or down.
Now lets try to visualize it in 3D (as seen from northern side looking southeast):
and now let's add water:
[Some explanation, as it may be not so easy to grasp 3D visuals:
* the level (angle) of tilt is of course exagerrated