The Alpine Fault and the Canterbury Earthquake
The Canterbury Plain on the South Island of New Zealand is uniquely placed at the convergence of the Australian and Pacific tectonic plates. Together they form a right lateral strike-slip fault called the Alpine Fault, in which the two plates move horizontally alongside each other. However, when the fault has ruptured (the plates have suddenly slipped), the two plates have also moved vertically, creating the Southern Alps as one side of the fault slips upwards. Figure 1: This graphic shows the subduction of the Pacific plate to the Australian Plate in the North Island while the South Island has a transform boundary causing the Alpine Fault ("Plate Collision"). The subduction of the plates causes uplift of the Southern Alps along the Alpine fault (GNS) Figure 2: Here’s another graphic showing the subduction of the Pacific plate to the Indo-Australian plate, with the strike-slip transform boundary on the South Island as the two plates move laterally (Cayfo...