The Alpine Fault is a geological fault that runs almost the entire length of New Zealand's South Island (c. 480 km) and forms the boundary between the Pacific Plate and the Indo-Australian Plate. The Southern Alps have been uplifted on the fault over the last 12 million years in a series of earthquakes. However, most of the motion on the fault is strike-slip (side to side), with the Tasman district and West Coast moving North and Canterbury and Otago moving South. The average slip rates in the fault's central region are about 38 mm a year, very fast by global standards. The last major earthquake on the Alpine Fault was in c. 1717 AD, the probability of another one occurring within the next 50 years is estimated at about 75 percent.

 

Note:   The above text is excerpted from the Wikipedia article Alpine Fault, which has been released under the GNU Free Documentation License.