Location map showing the plate tectonic configuration of New Zealand. The Pacific Plate is moving west at a rate varying from ~60 mm per year in the north to ~ 30 mm per year in the south, as shown by black arrows. The red lines with barbs (in the north) delineate the plate boundary, where the Pacific Plate is subducted beneath the Australian Plate (region with barbs). Note that here the black arrows are more or less orthogonal to the red line. To the south, the direction of the arrows becomes increasingly oblique as the plate boundary comes on-land and subduction gives way to transcurrent (lateral) movement.
East of the North Island, the Pacific Plate is dipping below the Australian Plate. This movement is causing the land to compress, squeeze upwards and move sideways. This map shows the direction and relative speed of the Pacific and Australian Plates in millimetres per year.