The Wairau Fault is an active

Active fault

An active fault is a fault that is likely to have another earthquake sometime in the future. Faults are commonly considered to be active if there has been movement observed or evidence of seismic activity during the last 10,000 years....

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

South Island

The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...

, New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

. It forms part of the Marlborough Fault System

Marlborough Fault System

The Marlborough Fault System is a set of four large dextral strike-slip faults and other related structures in the northern part of South Island, New Zealand, which transfer displacement between the mainly transform plate boundary of the Alpine fault and the mainly destructive boundary of the...

, which accommodates the transfer of displacement along the oblique convergent boundary between the Indo-Australian Plate

Indo-Australian Plate

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

 and Pacific Plate

Pacific Plate

The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million square kilometres, it is the largest tectonic plate....

, from the transform

Transform fault

A transform fault or transform boundary, also known as conservative plate boundary since these faults neither create nor destroy lithosphere, is a type of fault whose relative motion is predominantly horizontal in either sinistral or dextral direction. Furthermore, transform faults end abruptly...

 Alpine Fault

Alpine Fault

The Alpine Fault is a geological fault, more specifically known as a right-lateral strike-slip fault, that runs almost the entire length of New Zealand's South Island. It forms a transform boundary between the Pacific Plate and the Indo-Australian Plate. Earthquakes along the fault, and the...

 to the Hikurangi Trench

Hikurangi Trench

The Hikurangi Trench is a linear deep in the Pacific Ocean off the east coast of the North Island of New Zealand, lying between the southern end of the Cook Strait and the Chatham Rise. Though much shallower, it is the southward continuation of the Kermadec Trench and forms part of the...

 subduction zone

Subduction

In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...

.

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

Lake Rotoiti, Tasman

Lake Rotoiti is lake in the Tasman Region of New Zealand. It is a substantial mountain lake within the borders of the Nelson Lakes National Park. The lake is fed by the Travers River, water from it flows into the Buller River. The greatest depth is 82 metres and it is surrounded by beech forest...

 to Cloudy Bay

Cloudy Bay

Cloudy Bay is located at the northeast of New Zealand's South Island, to the south of the Marlborough Sounds. The area lends its name to one of the best known New World white wines although the grapes used in production of that wine are grown in the Marlborough wine region further inland.The bay...

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

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 Blenheim are sited...

 township, the fault splits into two strands. These two strands continue to within about 15 km of the coast near Renwick

Renwick, New Zealand

Renwick is a small town in Marlborough, New Zealand, close to the south bank of the Wairau River. It is located on State Highway 6, 12 km west of Blenheim. Havelock is 31 km north...

. Further to the east only the southernmost strand can be detected. It takes its name from the Wairau River

Wairau River

The Wairau River is one of the longest rivers in New Zealand's South Island. It flows for 170 kilometres from the Spenser Mountains , firstly in a northwards direction and then northeast down a long, straight valley in inland Marlborough.The river's lower reaches are noted for the surrounding...

, 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 Wiarau Fault is nearing the end of its interseismic period". The current estimated seismic hazard from the Wairau Fault is considered to be relatively high.