Editing Alpine Fault (section)

== Tectonics ==
The Australian plate, which is in the process of again separating from the [[Indo-Australian plate]],<ref>{{cite journal |last1=Keep |first1=Myra |last2=Schellart |first2=Wouter P. |title=Introduction to the thematic issue on the evolution and dynamics of the Indo-Australian plate |journal=[[Australian Journal of Earth Sciences]] |year=2012 |volume=59, 2012 |issue=6: THEMATIC ISSUE – Evolution and dynamics of the Indo-Australian plate |pages=807–808 |doi=10.1080/08120099.2012.708360 |bibcode=2012AuJES..59..807K |s2cid=128996831 }}</ref> is [[Subduction|subducting]] towards the east south of the South Island and the Pacific plate is subducting towards the west to the north. In the middle, the Alpine Fault is a [[transform boundary]] and has both dextral (right-lateral) strike-slip movement and uplift on the southeastern side.<ref name="Howarth2018">{{cite journal|title=Past large earthquakes on the Alpine Fault: paleoseismological progress and future directions|first1=Jamie D. |last1=Howarth |first2= Ursula A. |last2=Cochran |first3= Robert M. |last3=Langridge |first4= Kate |last4=Clark |first5= Sean J. |last5=Fitzsimons |first6=Kelvin |last6=Berryman |first7= Pilar |last7=Villamor |first8=Delia T. |last8=Strong|url= https://www.tandfonline.com/doi/epdf/10.1080/00288306.2018.1464658 |doi= 10.1080/00288306.2018.1464658| year=2018 |volume=61 |issue=3 |pages= 309–328| journal=New Zealand Journal of Geology and Geophysics |bibcode=2018NZJGG..61..309H |s2cid=134211005|url-access=subscription }}</ref> The uplift is due to an element of convergence between the plates, meaning that the fault has a significant [[Fault (geology)|high-angle reverse oblique component]] to its displacement.<ref name="gnsHome" /><ref name="Graham2008">{{Cite book|url=https://books.google.com/books?id=zjDMNwAACAAJ|title=A Continent on the Move: New Zealand Geoscience into the 21st Century|last=Graham|first=I. J.|date=2008|publisher=Geological Society of New Zealand|isbn=978-1-877480-00-3}}</ref>

In the northern section of the fault the transition to the Marlborough Fault System reflects transfer displacement between the mainly [[Transform fault|transform]] [[Plate tectonics|plate]] boundary of the Alpine fault and the mainly [[destructive boundary]] further northwards from the [[Hikurangi Subduction Zone]] to the [[Kermadec Trench]]. This has resulted in a complex splaying of faults,<ref>{{cite journal|last1 =Vermeer|first1 =J.L.|last2 =Quigley|first2 =M.C.|last3 =Duffy|first3 =B.G.|last4 =Langridge|first4 =R.M.|last5 =Pettinga|first5 =J.R.|year =2021|title =Structure and kinematics of active faulting in the Hope-Kelly and Alpine Fault intersection zone, South Island, New Zealand|journal =Tectonophysics|volume =813|at =228928|doi =10.1016/j.tecto.2021.228928|bibcode =2021Tectp.81328928V}}</ref> which is associated with large earthquakes adjacent to, but off the Alpine fault itself, such the [[1929 Murchison earthquake]], [[1968 Inangahua earthquake]] and [[1929 Arthur's Pass earthquake]].{{efn|Tectonically the faults responsive for the 1929 earthquakes and the 1968 earthquake in Westland and Canterbury are parallel to the Alpine fault and offset from it by about {{cvt|50|km}}.<ref name=GNSAF />}}

The Alpine Fault has the greatest uplift of the Pacific plate near [[Aoraki / Mount Cook]] in its central section. Here the relative motion between the two plates averages 37–40&nbsp;mm a year. This is distributed as 36–39&nbsp;mm of horizontal and 6–10&nbsp;mm upwards movement on the fault's plane per year.{{sfn|Graham|2015|p=|pp=120}} 
	
At the southern end of the fault there is effectively no uplift component of the Pacific plate<ref name="Norris2001">{{cite journal|first1=Richard J. |last1=Norris |first2= Alan F. |last2=Cooper |title=Late Quaternary slip rates and slip partitioning on the Alpine Fault, New Zealand |journal=Journal of Structural Geology |volume=23 |issue=2–3| date=2001-02-03 |pages=507–520 |issn=0191-8141  |doi=10.1016/S0191-8141(00)00122-X|url=https://www.sciencedirect.com/science/article/pii/S019181410000122X |bibcode=2001JSG....23..507N|url-access=subscription }}</ref> and other faults share the strain as a result of the plate collision.<ref name="Norris2004">{{cite journal|journal=Earth, Planets and Space |volume =56 |pages=1095–1101|year=2004 |doi=10.1186/BF03353328|last1=Norris |first1= Richard J.|title=Strain localisation within ductile shear zones beneath active faults: The Alpine Fault contrasted with the adjacent Otago fault system, New Zealand |issue =12 |bibcode =2004EP&S...56.1095N |s2cid =53613442 |url=https://link.springer.com/content/pdf/10.1186/BF03353328.pdf |doi-access =free }}</ref> These include in [[Fiordland]] faults associated with the [[2003 Fiordland earthquake]] and [[2009 Dusky Sound earthquake]], the [[Otago fault system]], in [[Canterbury, New Zealand|Canterbury]] faults such as the [[Ostler Fault Zone]] and those associated with the 7.1 M<sub>W</sub> [[2010 Canterbury earthquake|Darfield earthquake]]. The uplift in this South Westland region of the fault which has a dextral strike-slip rate of about {{convert|28|mm|abbr=on}}/year is on the Australian plate side of it with meter scale vertical uplift every 290 years odd.<ref name="Cochran2017">{{cite journal|first1=U.A. |last1=Cochran |first2= K.J. |last2=Clark |first3= J.D. |last3=Howarth |first4= G.P. |last4=Biasi |first5= R.M. |last5=Langridge |first6= P. |last6=Villamor |first7= K.R. |last7=Berryman |first8= M.J. |last8=Vandergoes |title=A plate boundary earthquake record from a wetland adjacent to the Alpine fault in New Zealand refines hazard estimates |journal=Earth and Planetary Science Letters |volume =464 |year=2017 |pages=175–188 |issn=0012-821X |doi=10.1016/j.epsl.2017.02.026 |bibcode=2017E&PSL.464..175C |url=https://www.sciencedirect.com/science/article/pii/S0012821X17300948|url-access=subscription }}</ref>