Alpine Fault

The Alpine Fault is a geological fault that runs almost the entire length of New Zealand's South Island, being about 600 km (370 mi) long, and forms the boundary between the Pacific plate and the 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 (1.5 in) a year, very fast by global standards. The last major seismic event on the fault was a great (magnitude of 8 or more) earthquake of Mw 8.1± 0.1 in about 1717 AD. The probability of another one occurring before 2068 was estimated at 75 percent in 2021.