Alpine Fault

The Alpine Fault , clearly visible as a straight line in the upper half of the image through the contrast between snow-capped mountains and green coastal plain, runs from the western end of the Southern Alps to the northeast tip of South Iceland .

This elevation-colored map shows the impact of the Alpine Fault on the surface of South Island. The width of the image section is 495 km, north-west is at the top

The Alpine Fault is a geological fault in the type of right-slip fault , the South Island ( South Iceland ) New Zealand crosses almost the entire length. It is a transform fault and forms the boundary between the Pacific and Indo-Australian plates . Earthquakes often occur here , and the movements at the fault are the reason for the formation of the Southern Alps . The uplift of the Southern Alps is due to the movement of theContinental plates does not run exactly parallel to here Alpine Fault, but slightly obliquely, so that the deferment is the eastern side.

course

The Alpine Fault occurs in the Macquarie Fault Zone in the Puysegur Trench off the southwestern end of the South Island. From there, it runs along the western end of the Southern Alps before splitting north of Arthur's Pass into a series of smaller right-handed leaf shifts known as the Marlborough Fault Zone . This zone consists of individual faults, including the Wairau Fault , Hope Fault , Awatere Fault, and Clarence Fault , and transmits the fault offset between the Alpine Fault and the Hikurangi Trench , a subduction zone north of New Zealand. The Hope Fault is considered to be the main continuation of the Alpine Fault.

The mean movement rates in the central section of the fault are around 30 mm per year, and are very high by global standards. The movements at the Alpine Fault have caused Zealandia , the microcontinent surrounding New Zealand, to be split up, displacing both halves by about 500 km.

Historical earthquakes

Several major earthquakes have occurred at the Alpine Fault and its northern continuations in historical times:

• 1848 - 1848 Marlborough earthquake , with a strength of 7.8  M _W
• 1888 - 1888 North Canterbury earthquake , with a strength of 7.1  M _W
• 1929 - Arthur's Pass earthquake of 1929 , magnitude 7.1  M _S
• 1929 - Murchison earthquake of 1929 , magnitude 7.8  M _S
• 1968 - Inangahua Earthquake of 1968 , with the strength of 7.1  M _W
• 2003 - Fiordland earthquake of 2003 , with the strength of 7.2  M _W
• 2009 - Dusky Sound earthquake of 2009 , with the strength of 7.8  M _W

Great fracture movements

The movements on the Alpine Fault and its southward and northward continuation mean that smaller fracture movements are constantly taking place, and large fractures are also not uncommon.

In the past thousand years, the Alpine Fault has experienced four major fracture movements that generated earthquakes with magnitudes greater than 8. According to paleoseismic investigations, they occurred at a distance of about 100 to 350 years, namely around 1100, 1450, 1620 and 1717 AD. The last of these fracture movements in 1717 seems to have affected about 400 km of the Alpine Fault . Since almost three hundred years have passed since this event, such an event could repeat itself at any time.

See also

• plate tectonics
• seismology

literature

• R. Robinson : Potential earthquake triggering in a complex fault network: the northern South Island, New Zealand . In: Geophysical Journal International . tape 159 , no. 2 , 2003, p. 734-748 .
• A. Wells, MT Yetton, RP Duncan, GH Stewart : Prehistoric dates of the most recent Alpine fault earthquakes, New Zealand . In: Geology . tape 27 , no. 11 , 1999, p. 995-998 ( online abstract ).

Web links

• Alpine Fault - Tectonic setting of New Zealand: astride a plate boundary which includes the Alpine Fault . University of Otago - Geology Department,accessed January 21, 2016. 
• New Zealand Active Faults Database . Institute of Geological & Nuclear Sciences Limited (GNS),accessed August 9, 2012(English, maps, photos and references to New Zealand's active faults). 
• New Zealand in relation to the Indo-Australian and Pacific Plates . Ministry for the Environment ,accessed August 9, 2012. 

Individual evidence

1. ^ Judith Zachariasenae, Kelvin Berrymana, Robert Langridgeb, Carol Prenticec, Michael Rymerc, Mark Stirlingd, Pilar Villamord : Timing of late Holocene surface rupture of the Wairau Fault, Marlborough, New Zealand . In: New Zealand Journal of Geology and Geophysics . Volume 49 , 2006, pp.  159-174 , doi : 10.1080 / 00288306.2006.9515156 .
2. ↑ Where were New Zealand's largest earthquakes? . GNS Science , accessed on January 21, 2016 .  
3. ↑ A clearer picture of the Alpine Fault's earthquake history . Geological & Nuclear Sciences Limited (GNS) , September 10, 1998, archived from the original on May 26, 2010 ; accessed on August 9, 2012 .  
4. ↑ Jarrod Booker : Deadly alpine quake predicted . New Zealand Herald , August 24, 2006, accessed August 9, 2012 .