Awatere Fault

Last updated
Awatere Fault
LocationSouth Island, New Zealand
CountryNew Zealand
Characteristics
Segments2; Molesworth and Eastern
Length175km
Tectonics
Plate Australian Plate, Pacific Plate
StatusActive
Earthquakes 1848 Marlborough earthquake
Type dextral strike-slip fault
New Zealand geology database (includes faults)
Map of the Marlborough Fault System MarlboroughFaultSystem.png
Map of the Marlborough Fault System

The Awatere Fault is an active dextral (right lateral) strike-slip fault in the northeastern part of South Island, New Zealand. It forms part of the Marlborough Fault System, which accommodates the transfer of displacement along the oblique convergent boundary between the Indo-Australian Plate and Pacific Plate, from the transform Alpine Fault to the Hikurangi Trench subduction zone. [1] The 1848 Marlborough earthquake was caused by rupture of the whole of the eastern section of the Awatere Fault.[ citation needed ]

Contents

Extent

The 175 km long Awatere Fault is formed of two main segments; the Molesworth section to the southwest and the Eastern section to the northeast. [2] A further strand links the southwestern end of the Eastern section to the Clarence Fault, passing through Barefell Pass. [3]

Molesworth section

The Molesworth segment of the Awatere Fault runs from close to the junction between the Alpine and Wairau Faults near Lake Tennyson, to near Molesworth Station in the northeast. It is about 55 km in length and consists of several smaller segments. This section has an overall strike of N75–80°E, giving local zones of transtension at some of the segment boundaries, such as at Isolated Flat. [4]

Eastern section

The Eastern section of the fault runs from Molesworth Station to the coast, near White Bluffs, without significant segmentation. [3] The Awatere River follows the trace of much of the eastern section of the fault, giving its name to the whole structure.[ citation needed ]

Recent seismicity

The Molesworth section appear to have moved twice since about 3000 years ago, in events with slip values of about 6–7 m. [4] Trenching at Saxton River at the eastern end of the Molesworth section suggests 8 ruptures since about 6,300 years ago, with an estimated mean recurrence of about 800 years. [5] Evidence from the eastern section of the fault suggests that there were 9–10 earthquakes in the period from 8610 BP to AD 1848. This gives a mean recurrence interval of 820–950 years. [6] In 1848 a minimum 105 km length section of the fault ruptured, causing an earthquake of an estimated magnitude of about 7.5 Mw . The rupture appears to have bypassed the Molesworth section of the fault, continuing on the southern strand through Barefell Pass. [3]

Seismic hazard

Seismic hazard on the Eastern section is considered low, with only about 150 years since the last major earthquake on that section and an estimated recurrence interval of 600–2500 years. [2]

Related Research Articles

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The Alpine Fault is a geological fault that runs almost the entire length of New Zealand's South Island, being about 600 km (370 mi). long, and forms the boundary between the Pacific Plate and the Australian Plate. 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, with the Tasman district and West Coast moving north and Canterbury and Otago moving south. The average slip rates in the fault's central region are about 38 mm (1.5 in) a year, very fast by global standards. The last major earthquake on the Alpine Fault was in about 1717 AD with a great earthquake magnitude of Mw8.1. The probability of another one occurring within the next 50 years is estimated at 75 percent.

<span class="mw-page-title-main">Hope Fault</span> Active fault in New Zealand

The Hope Fault is an active dextral strike-slip fault in the northeastern part of South Island, New Zealand. It forms part of the Marlborough Fault System, which accommodates the transfer of displacement along the oblique convergent boundary between the Indo-Australian Plate and Pacific Plate, from the transform Alpine Fault to the Hikurangi Trench subduction zone.

<span class="mw-page-title-main">San Jacinto Fault Zone</span> Southern Californian fault zone

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<span class="mw-page-title-main">Wairau Fault</span> Active fault in New Zealand

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<span class="mw-page-title-main">Clarence Fault</span> Active fault in New Zealand

The Clarence Fault is an active dextral strike-slip fault in the northeastern part of South Island, New Zealand. It forms part of the Marlborough Fault System, which accommodates the transfer of displacement along the oblique convergent boundary between the Indo-Australian Plate and Pacific Plate, from the transform Alpine Fault to the Hikurangi Trench subduction zone.

<span class="mw-page-title-main">North Island Fault System</span> Fault zone of the east coast of New Zealands North Island

The North Island Fault System (NIFS) is a set of southwest–northeast trending seismically-active faults in the North Island of New Zealand that carry much of the dextral strike-slip component of the oblique convergence of the Pacific Plate with the Australian Plate. However despite at least 3 km (1.9 mi) of uplift of the axial ranges in the middle regions of the fault system during the last 10 million years most of the shortening on this part of the Hikurangi Margin is accommodated by subduction.

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The Wellington Fault is an active seismic fault in the southern part of the North Island of New Zealand. It is a dextral (right-lateral) strike-slip fault with variable amounts of vertical movement causing uplift to the northwest, as expressed by a series of ranges. It forms part of the North Island Fault System, which accommodates the transfer of displacement along the oblique convergent boundary between the Indo-Australian Plate and Pacific Plate.

The 1934 Pahiatua earthquake struck at 11:46 pm on 5 March, causing severe damage in much of the lower North Island. Wairarapa, Wellington and Hawke's Bay felt the strongest levels of shaking, with much of New Zealand feeling the tremor.

<span class="mw-page-title-main">Kekerengu Fault</span> Active fault in New Zealand

The Kekerengu Fault is an active dextral strike-slip fault in the northeastern part of South Island, New Zealand. It is closely associated with the Hope Fault and Jordan Thrust at its south-easternmost edge and likely joins with the Clarence Fault to form the Wairarapa Fault offshore in Cook Strait.

The 1850 Xichang earthquake rocked Sichuan Province of Qing China on September 12. The earthquake which caused major damage in Xichang county had an estimated moment magnitude of 7.6–7.9 Mw  and a surface wave magnitude of 7.5–7.7 Ms . An estimated 20,650 people died.

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The Keichō–Fushimi earthquake struck Japan on September 5, 1596. The earthquake measuring 7.5 ± 0.25 MJMA produced intense shaking across the Kansai region. Devastation was recorded in Kyoto and over 1,200 people perished.

<span class="mw-page-title-main">Wairoa North Fault</span> Active fault in New Zealand

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The Rangipo Fault is the eastern Taupō rift-bounding north–south striking normal fault complex of the Ruapehu Graben, a seismically active area of the central North Island of New Zealand to the west of Mount Ruapehu. It could be part of a Mw7.1 potential rupture.

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<span class="mw-page-title-main">Ostler Fault Zone</span> Fault zone in New Zealand

The Ostler Fault Zone is an active fault zone, to the east of the Alpine Fault in South Canterbury, South Island of New Zealand. It has had multiple recent rupture events greater than ML6.5 in magnitude, with a recent 6.9 to 7.0 event, and has recently accommodated 1.9 mm (0.075 in)/year of compression and thus land contraction.

The Hundalee Fault in northern coastal Canterbury, New Zealand had a significant rupture in the 7.8 Mw 2016 Kaikōura earthquake for a minimal length of 23 km (14 mi) and as such was a key linkage fault in this complex earthquake. It is located between Parnassus in the Hurunui District and runs off shore from near Oaro.

References

  1. ↑ Langridge, R.; Campbell J.; Hill N.; Pere V.; Pope J.; Pettinga J.; Estrada B.; Berryman K. (2003). "Paleoseismology and slip rate of the Conway Segment of the Hope Fault at Greenburn Stream, South Island, New Zealand" (PDF). Annals of Geophysics. 46 (5). Retrieved 27 June 2010.
  2. 1 2 Geotech Consulting Ltd (May 2003). "Identification of active fault traces in Marlborough District". Marlborough District Seismic Hazard Investigation Programme. Archived from the original on 22 May 2010. Retrieved 2 July 2010.
  3. 1 2 3 Grapes, R.; Little T.A.; Downes G. (1998). "Rupturing of the Awatere Fault during the 1848 October 16 Marlborough earthquake, New Zealand: historical and present day evidence" (PDF). New Zealand Journal of Geology & Geophysics. 41 (4): 387–399. Bibcode:1998NZJGG..41..387G. doi:10.1080/00288306.1998.9514818 . Retrieved 2 July 2010.[ permanent dead link ]
  4. 1 2 McCalpin, J.P. (1996). "Tectonic geomorphology and Holocene paleoseismicity of the Molesworth section of the Awatere Fault, South Island, New Zealand" (PDF). New Zealand Journal of Geology and Geophysics. 39 (1): 33–50. Bibcode:1996NZJGG..39...33M. doi:10.1080/00288306.1996.9514693 . Retrieved 2 July 2010.[ permanent dead link ]
  5. ↑ Little, T. "Stop 2: Awatere Fault - south of Dashwood Pass at Calrossie Station" (PDF). Field Trip Guides, Geological Society of New Zealand 50 Annual Conference, Kaikoura, New Zealand. p. 92. Archived from the original (PDF) on 25 May 2010. Retrieved 2 July 2010.
  6. ↑ Mason, D.P.M.; Little T.A.; van Dissen R.J. (2006). "Refinements to the paleoseismic chronology of the eastern Awatere Fault from trenches near Upcot Saddle, Marlborough, New Zealand". New Zealand Journal of Geology and Geophysics. 49 (3): 383–397. Bibcode:2006NZJGG..49..383M. doi:10.1080/00288306.2006.9515175. S2CID   128479940.
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