Alpine Fault, New Zealand

The Alpine Fault runs for about 600 kilometers along nearly the entire length of New Zealand's South Island, forming the boundary between the Pacific and Australian tectonic plates through the Southern Alps of the West Coast and Southland regions. It is a strike-slip fault with a strong uplift component, and its central section slips at roughly 38 millimeters a year, among the fastest rates recorded anywhere in the world. Geologist Harold Wellman first identified the structure in 1940 from the way the Southern Alps lined up with it, and the fault was formally named in 1942 as an extension of an already-mapped feature. Its last great rupture, estimated at magnitude 8.1, struck around 1717, and a 2021 hazard assessment put the probability of another such earthquake before 2068 at 75 percent. This entity documents the Alpine Fault specifically as a geological formation.