Geology of New Zealand - Land Movement

Land Movement

Because New Zealand straddles a plate boundary, it is tectonically active. The Pacific Plate is colliding with the Australian Plate at a rate of about 40 mm/yr.

The East coast of the North Island is being compressed and lifted by this collision, producing the North Island and Marlborough Fault Systems. The East Coast of the North Island is also rotating clockwise, relative to Northland, Auckland and Taranaki, stretching the Bay of Plenty, and producing the Hauraki Rift (Hauraki Plains and Hauraki Gulf) and Taupo Volcanic Zone.

The East Coast of the South Island is sliding obliquely towards the Alpine Fault, relative to Westland, causing the Southern Alps to rise about 10 mm/yr (although they are also worn down at a similar rate).

The Hauraki Plains, Hamilton, Bay of Plenty, Marlborough Sounds, and Christchurch are sinking. The Marlborough Sounds are known for their sunken mountain ranges. As Wellington rises, and Marlborough sinks, Cook Strait is being shifted further south.