The Alpine Fault is easily visible from space, running along the western edge of the [[Southern Alps from the south-western coast towards the north-eastern corner of the
South Island. This scene was acquired by NASA's Terra satellite, on October 23, 2002.]]
The
Alpine Fault is a geological fault, known as a right-lateral strike-slip fault, that runs almost the entire length of
New Zealand's
South Island. It forms a
transform boundary between the
Pacific Plate and the
Indo-Australian Plate. Earthquakes along the fault, and the associated earth movements, have formed the
Southern Alps.
Beginning off the south-western corner of the South Island, the Alpine Fault runs along the western edge of the Southern Alps, then splits into three parallel faults north of
Arthur's Pass. Average slip rates in the fault's central region are about 30mm a year, very fast by global standards.
Historic Earthquakes
The Alpine Fault has experienced sizeable earthquakes in historic times:
- 1929 - Arthur's Pass. Estimated magnitude = 7.1.
- 1929 - Murchison. Estimated magnitude = 7.8.
- 1968 - Inangahua. Estimated magnitude = 7.1.
- 2003 - Fiordland. Estimated magnitude = 7.1.
Major Ruptures
Over the last thousand years, there have been four major ruptures along the Alpine Fault causing earthquakes of about magnitude 8. These occurred in approximately 1100, 1450, 1620 and 1717 AD, at intervals between 100 and 350 years. The 1717 quake appears to have involved a rupture along nearly 400km of the southern two thirds of the fault. Scientists' best estimate is that there is a high likelihood of a similar earthquake within a few decades.
Large ruptures can also trigger earthquakes on the faults continuing north from the Alpine Fault.
See also
External links
University of Otago Geology Department:
Institute of Geological & Nuclear Sciences Limited (GNS):
Miscellaneous:
Category:Geography of New Zealand
Category:Seismic faults
Category:Plate tectonics
Category:Faults