The Wairau Fault is an

active Active may refer to: Music * ''Active'' (album), a 1992 album by Casiopea * Active Records, a record label Ships * ''Active'' (ship), several commercial ships by that name * HMS ''Active'', the name of various ships of the British Royal ...

dextral (right lateral) strike-slip fault in the northeastern part of South Island,

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

. It forms part of the Marlborough Fault System, which accommodates the transfer of displacement along the oblique convergent boundary between the

Indo-Australian Plate The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and the surrounding ocean and extends northwest to include the Indian subcontinent and the adjacent waters. It was formed by the fusion of the Indian an ...

and Pacific Plate, from the

transform Transform may refer to: Arts and entertainment * Transform (scratch), a type of scratch used by turntablists * ''Transform'' (Alva Noto album), 2001 * ''Transform'' (Howard Jones album) or the title song, 2019 * ''Transform'' (Powerman 5000 album ...

Alpine Fault The Alpine Fault is a geological fault that runs almost the entire length of New Zealand's South Island (c. 480 km) and forms the boundary between the Pacific Plate and the Indo-Australian Plate. The Southern Alps have been uplifted on the f ...

to the Hikurangi Trench subduction zone.

Extent

Depending on the precise definition used, the Wairau Fault runs either from southern or northern end of 'The Bends' region. In the former case it is regarded as the Wairau segment of the Alpine Fault. In the latter case it is regarded as a separate fault and runs about 100 km from near Lake Rotoiti to

Cloudy Bay Te Koko-o-Kupe / Cloudy Bay is located at the northeast of New Zealand's South Island, to the south of the Marlborough Sounds and north of Clifford Bay. In August 2014, the name Cloudy Bay, given by Captain Cook in 1770, was officially altered t ...

in the east. To the west, the fault is a single strand but near

Wairau Valley Wairau Valley is the valley of the Wairau River in Marlborough, New Zealand and also the name of the main settlement in the upper valley. State Highway 63 runs through the valley. The valley opens onto the Wairau Plain, where Renwick and Blen ...

township, the fault splits into two strands. These two strands continue to within about 15 km of the coast near Renwick. Further to the east only the southernmost strand can be detected. It takes its name from the

Wairau River The Wairau River is one of the longest rivers in New Zealand's South Island. It flows for from the Spenser Mountains (a northern range of the Southern Alps), firstly in a northwards direction and then northeast down a long, straight valley in ...

, which follows the fault trace for most of its length.

Recent seismicity

From the offset of dated river terraces a displacement of 23 m has been estimated along the Wairau Fault since about 5610 yrs BP. Trenching studies along the trace of the Wairau Fault have identified four dateable slip events within this interval, the age of latest event falls in the range 1811–2301 BP. The average recurrence interval for earthquakes along this fault is in the range 1150–1400 yrs. The estimated average slip for each event is about 6 m.

Seismic hazard

The recurrence interval of slip events estimated for the fault combined with the estimated time since the last event suggest "that the Wairau Fault is nearing the end of its interseismic period". The current estimated seismic hazard from the Wairau Fault is considered to be relatively high.

References

{{Seismic faults of New Zealand Seismic faults of New Zealand Strike-slip faults