Wellington Fault at Thorndon
The Wellington Fault is one of several large active faults in the lower North Island of New Zealand. From the Tararua Mountains and Kaitoke it runs the length of the Hutt Valley, the edge of Wellington Harbour, through Tinakori in the City and across the hills to Cook Strait.
Hutt River at Mains Rock
Looking North along the Hutt River at Mains Rock

Earthquakes occur on the Wellington Fault approximately every 700 to 1000 years on average, with the last between 170 and 370 years ago. The probability of a rupture in the next 100 years is calculated to be about 10%. Because it runs along the highly populated Hutt Valley and right through the Capital City via its transport bottleneck, it is regarded as one of the country’s highest risk faults.

Wellington Fault Scarp beyond Lower Hutt
Wellington Fault Scarp beyond Lower Hutt

You can find out information about all of New Zealand’s known active faults on the GNS Science Active Faults Database, but in this image you can see a screen grab of those known in the Wellington area, some of them labelled:

As you can see there are many other faults in the region, each of which is capable of rupturing, so that the real possibility of a large earthquake occurring at some point from one or other of the faults is something that should inspire everyone to be prepared. (Make some time to go to https://getready.govt.nz/ )

Active Faults in the Wellington Region
Active Faults in the Wellington Region

As you can see there are many other faults in the region, each of which is capable of rupturing, so that the real possibility of a large earthquake occurring at some point from one or other of the faults is something that should inspire everyone to be prepared. (Make some time to go to https://getready.govt.nz/ to get the best information on how to do this.)

Here is an aerial view of the Wellington Fault trace (bottom right to centre top of the photo) passing through California Park in Upper Hutt and along the centre of  California Drive beyond

The Wellington Fault trace seen from above California Park, Upper Hutt
The Wellington Fault runs through California Park and along California Drive in Upper Hutt

In neighbouring Harcourt Park, the fault crosses a flight of river terraces at a right angle. This allows us to see clearly that the slip (movements) on the fault are mostly horizontal with some vertical movement as well. Looking across the fault the opposite side moves to the right. This means that the fault is a “dextral oblique slip fault”.
 
This diagram shows how the Harcourt Park River Terraces are offset by the Wellington Fault
Harcourt Park Offset River Terraces
Harcourt Park River Terraces offset by the Wellington Fault
The fault can be followed along the Hutt River. In Lower Hutt it runs right along the side of Hutt Road, and into Petone. This photo shows the fault scarp at the end of Te Mome Road where it meets Hutt Road at a T junction:
 
Wellington Fault scarp on Te Mome Road
Wellington Fault scarp on Te Mome Road

The entrance to Wellington City at Thorndon is a bottleneck, where the Wellington Fault passes underneath the railway, State Highway and Ferry Terminal, as well as the water supply. This makes Wellington vulnerable to being cut off by a rupture of the Wellington Fault.

The Wellington Fault at Thorndon
The Wellington Fault crosses critical infrastructure at Thorndon:
Wellington Fault at Thorndon
Wellington Fault at Thorndon

You can learn more by visiting the Wellington Fault at several points from Upper Hutt to Wellington. Check out this video for details:

 

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