Editing Alpine Fault (section)

{{Short description|Large geological fault in New Zealand}}
{{Use New Zealand English|date=March 2024}}
{{Infobox fault
| name              = Alpine Fault
| other_name        = 
| named_for         = [[Southern Alps]]
| named_by          = 
| year_def          = 
| image             = Zealandia-Continent map en.svg
| image_alt         = 
| caption           = Movement along the Alpine Fault is deforming the continent of [[Zealandia (continent)|Zealandia]], with the southern part (on the [[Pacific plate]]) sliding past and slightly onto the northwest part (on the [[Australian plate]]).
| map_image         ={{maplink|frame=yes
|frame-align=center
|text=Map of active Alpine Fault on land (red). Click on the map to enable mouse over of fault features.<ref name=GNSAF>{{cite web|url=https://data.gns.cri.nz/af/ | title=GNS:New Zealand Active Faults Database|access-date=2023-04-29}}</ref>
|raw={{Wikipedia:Map data/Alpine Fault}}
|frame-width=280
|frame-height=300 
|frame-lat=-43.5
|frame-long=172.3
|icon=no
|zoom=5
}}
| map_alt           = 
| pushpin_map       = 
| pushpin_map_width = 
| pushpin_map_caption =
| pushpin_map_alt   = 
| pushpin_relief    = 1
<!-- location -->
| country           = [[New Zealand]]
| region            = [[West Coast, New Zealand|West Coast]] and [[Southland, New Zealand|Southland]] regions
| state             = 
| cities            = 
| coordinates       = 
| elevation         = 
| elevation_ft      = 
| elevation_ref     = 
| topdepth_m        = 
| topdepth_ft       = 
| topdepth_ref      = 
| range             = [[Southern Alps]]
| part_of           = 
| segments          = 
| length            = {{convert|600|km|mi|abbr=on}}
| width             = 
| depth             = 
| strike            = NE-SW
| dip               = 
| dip_angle         = 
| displacement      = {{convert|30|mm|in|abbr=on}}/yr
| plate             = [[Australian plate|Australian]], [[Pacific plate|Pacific]]
| status            = [[Active fault|Active]]
| earthquakes       = 1717 prehistoric 
| type              = [[Strike-slip fault]]
| movement          = Up to {{M|w|8.2|link=y}},<ref name="Howarth2018"/> dextral/convergent, east side up
| rockunit          = 
| age               = [[Miocene]]-[[Holocene]] {{Geological range|12|0.0003|ref=<ref name="Cochran2017"/>}}
| orogeny           = [[Kaikoura Orogeny|Kaikoura]]
| volcanic_arc/belt = 
| embed             = [https://data.gns.cri.nz/geology/ New Zealand geology database (includes faults)]
}}
[[File:South Island blizzard 2003.jpg|thumb|right|310px|Snow delineates the [[escarpment]] formed by the Alpine Fault along the [[Southern Alps (New Zealand)|Southern Alps]]' north-west edge, near the [[South Island]]'s west coast. This satellite image shows the aftermath of a blizzard that hit the island in July 2003.]]
The '''Alpine Fault''' is a [[Fault (geology)|geological fault]] that runs almost the entire length of [[New Zealand|New Zealand's]] [[South Island]], being about {{convert|600|km|abbr=on}}.<ref group=lower-alpha name="lengthnotes">A former length quoted in the article introduction at 480&nbsp;km, was noted on article review in May 2023 to be discordant with the length presently quoted in the reference used which is of 600&nbsp;km. This source, while not an original academic work is an respected source so length was corrected back after further validation as explained in this note. It is quite possible that the reference was updated after the access date of 2018-12-31 or that the 480&nbsp;km figure is actually the length of off set of the fault, inserted in easy to make error, and indeed the offset constrains the minimum length of the fault. It was further noted that another non academic reference to length of the fault used later in the article claimed a fault length of 850&nbsp;km. This source, when checked was a press statement on research findings, so not peer-reviewed and is possibly from Nathan 2011 as source. It has been corrected too with context. Berryman's group started using a 800&nbsp;km figure in their 2012 academic work, which is an increased length from Berryman et al. (1992). This gave a 650&nbsp;km length including the Wairau Fault which many workers do not include in the fault length. There is no evidence yet of full rupture including the [[Wairau Fault|Wairau Fault (see article)]]. There is evidence for off shore full length fault rupture however as in the 1717 event. The 800&nbsp;km length includes the Wairau Fault and assumes the off shore portion ends just south of Fiordland. The length of the fault will depend upon how much if any of the southern off shore portion is included or if the Wairau Fault is added. The [https://data.gns.cri.nz/af/ GNS New Zealand Active Fault database] maps about 520&nbsp;km of fault on land or if the fault was a straight line end to end about 500&nbsp;km. The total length of the South Island is about 800&nbsp;km for reference. Academic work on the fault does not always state its total length.</ref> long, and forms the boundary between the [[Pacific plate]] and the [[Australian plate]].<ref name="gnsHome">{{Cite web|url=https://www.gns.cri.nz/Home/Learning/Science-Topics/Earthquakes/Major-Faults-in-New-Zealand/Alpine-Fault|title=Alpine Fault / Major Faults in New Zealand / Earthquakes / Science Topics / Learning / Home – GNS Science|website=gns.cri.nz|access-date=2023-10-11}}</ref> 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 tectonics|strike-slip]] (side to side), with the [[Tasman District|Tasman district]] and [[West Coast, New Zealand|West Coast]] moving north and [[Canterbury, New Zealand|Canterbury]] and [[Otago]] moving south. The average slip rates in the fault's central region are about {{convert|38|mm|abbr=on}} a year, very fast by global standards.{{sfn|Graham|2015|p=|pp=120}} The last major earthquake on the Alpine Fault was in about 1717 AD with a ''great'' earthquake magnitude of {{M|w|8.1|link=y}}±&nbsp;0.1.<ref name="Howarth2018"/> The probability of another one occurring before 2068 was estimated at 75 percent in 2021.<ref name="GNS2021">{{cite web|url=https://www.gns.cri.nz/news/research-finds-alpine-fault-quake-more-likely-in-the-next-50-years/|title= Research finds Alpine Fault quake more likely in the next 50 years, Our Science, 01 June 2021|date=1 June 2021|website=gns.cri.nz|access-date=30 March 2024}}</ref><ref name="rnz">{{cite web|url=https://www.rnz.co.nz/news/national/440834/alpine-fault-probability-of-damaging-quake-higher-than-previously-thought|title=Alpine Fault: Probability of damaging quake higher than previously thought |website=[[RNZ]] |date=20 April 2021 |access-date=3 December 2021}}</ref>