The
Australian Plate is subducting under the Pacific Plate at a rate of /year at the Puysegur Trench. The northern end of the trench rises to meet the Resolution Ridge off the south western tip of New Zealand's
Fiordland and the
Alpine Fault continues north as the plate boundary. The southern part of the trench is adjacent to the Puysegur Ridge to its west which contains the Puysegur Fault. North of the Puysegur Ridge and Fault there multiple faults in the Snares Zone which transit south of the
South Island to named faults such as the Hauroko Fault, Solander Fault, and Parara Fault. The Puysegur Ridge becomes the Puysegur Bank north of the Snares Zone and south of Fiordland.
Earthquakes The area around the Puysegur Trench is highly seismically active, with the
Alpine Fault starting at the trench's northern end. In July 2009, New Zealand's
third-largest recorded earthquake (
magnitude 7.8) struck close to the northern end of the trench off the coast of
Fiordland. There have also been recent large earthquakes there in
2003 and 2004. Models have shown that the southern portion of the trench is capable of rupturing in a magnitude 8.5–8.6 earthquake. An 8.7 magnitude earthquake in the trench would create a tsunami as high as 7 metres in South Island's coasts according to a research in October 2011.
Arc Volcanism As the subduction is south east to north west, the associated arc volcanism, which may be relatively recent in last known of manifestation at 50,000 years ago, is in the Solander Islands, which are visible from the coast of the
Southland,
New Zealand. ==References==