Wellington Faultline walk (1)

earthquake walk 2 004With the shaky times we were having a few months ago, I was reminded of a walk I did along the Wellington Fault, following it southwards from the harbour to Cook Strait, on two separate days.

The Wellington Fault can be clearly seen, slicing through Wellington. From a vantage point like Wright’s Hill in Karori, it creates a long line of afternoon shadow, through the Zealandia sanctuary, down Glenmore Street, beside the cliffs that run along the motorway and on up the Hutt Valley.  You can also see the route it takes on this GNS Science video.

Wellington is actually on or close to three major fault lines: the Wellington Fault, the Ohariu Fault and the Wairarapa Fault, as well as many minor ones.  The Wellington Fault is the southern section of the North Island’s longest faultline – the Wellington-Mōhaka Fault, which runs from Cook Strait through to the Bay of Plenty.

I start my walk on an intensely bright early summer day, at the side of the Interislander arrivals building, which is where the faultline leaves the harbour and cuts through the CBD.  The sea is a chalky turquoise, choppy in the southerly breeze.

misc dec 09 021

Tucked away at the water’s edge is a rather crude memorial made from a stone provided by the people of Pusan (now Busan) in Korea, to four frigates and 1,749 NZ Army personnel that left Wellington for the Korean war.

Overhead is the motorway overbridge, with its massive reinforced pillars, a reminder, as if we need one, of the vulnerability of Wellington’s transport infrastructure.  When I first moved here I was amazed at how easily weather events, let alone earthquakes could cut Wellington off from the rest of the country, where the only two roads out are a coastal road subject to landslips and a winding hill road that can be closed by high winds and snow.  The recent winter storm and quakes showed how easily train services can be disrupted.  In a major quake, the harbour would apparently be full of the logs that are stacked up in the port, preventing access by sea, and the low-lying airport would be at risk of liquefaction and tsunami.

From the ferry terminal, the faultline crosses under the Hutt Road and then runs up through Thorndon.  To get there, I negotiate a concrete jungle of overpasses and slip roads, edged with pohutakawa trees coming into bloom.  The underside of one of the overbridges consists of parallel rows of arches receding into the distance, a brutalist concrete version of the mosque at Cordoba.

Underside of concrete bridge, Hutt Road

Underside of concrete bridge

misc dec 09 030I cross over the railway line and take some steps down to the Hutt Road.  An advertising board outside Guthrie Bowron is offering a free chicken with every purchase of ten litres of paint which seems an odd combination.  Would the chicken be dead or alive, I wonder.  And, if dead,  is there a vegetarian alternative?

I take the zigzag walkway up to Tinakori Road and the weatherboard villas of Thorndon.  As one of the first areas of Wellington to be settled, Thondon’s early residents would have been shaken by the magnitude 7.5 Marlborough earthquake in 1848, which caused extensive damage in Wellington; and a few years later by the earthquake on 23rd January 1885 – the last major Wellington earthquake and, at about magnitude 8.2, the most powerful New Zealand earthquake on record. The population of Wellington at the time numbered 3,200 and many of them had been out celebrating the 15th anniversary of the settlement when it struck at 9.17pm.

Brick buildings were badly damaged and most wooden buildings lost their brick chimneys.  The tide in the harbour rose over 2 metres and flooded houses and shops along the beach, and then receded well below the low tide level and continued to do so every 20 minutes for the next 8 hours.  A tsunami rose in Cook Strait, flowing over the low lying Rongotai isthmus, into the harbour and then flowing back again.  A fissure appeared down Willis Street, oozing mud.  Accounts describe aftershocks every few minutes, followed by a rush of wind. Surprisingly, there was only one casualty – the Baron von Alzdorf in his ‘indestructible’ hotel on Lambton Quay (which I wrote about in this post).

The effect of the earthquake on the land was dramatic, and ironically, to the benefit of the early settlers.  Land around the harbour was uplifted by around one metre, creating more flat land.  It drained the Te Aro swamp, providing land for development and allowed the narrow and dangerous road around the harbour to the Hutt Valley and beyond to the Wairarapa, to be widened, and at a much later date, the uplifted flat land of the Rongotai isthmus was used for the airport.

Little George Street, Thorndon

Little George Street, Thorndon

The faultline runs more or less parallel to Tinakori Road and runs directly along Burnell Avenue, Goring Street and Little George Street, where the houses on one side of the street are higher than the houses on the other.  Many of Thorndon’s houses are built directly over the faultline.  The faultline even runs straight through the grounds of Premier House, the Prime Minister’s official residence in Wellington.  I’d wondered how proximity to the faultline affects house prices in this expensive part of town, but a check of rateable values suggests that this isn’t the case.

I zig-zag through Thorndon’s side streets lined with small former worker’s cottages.  Everything feels quiet in the lunchtime sun.  A cat is stretched out asleep on a doorstep.

I’m feeling in need of coffee, but the cafes along Tinakori Road all seem to be closed.  I make a short detour to the cafe in the Botanic Gardens.  The rocks along the entrance driveway to the Gardens have apparently been crushed by movements along the faultline.  I sit among the roses and the tourists drinking my flat white.  The sky is still clear and the dark pines of Tinakori Hill are almost shimmering in the intensity of the midday sun.

Living on the relatively solid ground of the British Isles, I used to wonder why people lived near major faultlines.  But now, especially after Christchurch and after Wellington’s much smaller recent shakes, I don’t anymore.  People live near faultlines for the same wide variety of reasons they drive cars, smoke cigarettes, or live in places that are at risk of bushfires or terrorist attack.  Risks are impossible to avoid and we take them all the time, even though our judgements about the risks we can live with are not always logical.

Some people left Wellington after the 1855 quake, but not as many as after the Marlborough earthquake in 1848.  Up to the 1848 quake, the early settlers had regarded the frequent earth tremors as relatively benign, and were surprised and terrified by the first major earthquake they experienced.  Over sixty settlers set sail for Sydney on the Subraon, only be wrecked on rocks near the entrance to Wellington Harbour. They were all rescued but many decided to stay in Wellington after that, perhaps thinking they were doomed to be in Wellington.

I leave the roses and carry on walking up the long valley of Glenmore Street, the neat beds of the Botanic Gardens on one side of the street and on the other, untidy steep banks of grass tangled up with nasturtiums, monbretia, and tradescantia.

Zealandia lower reservoirThe faultline runs in front of the Karori tunnel and through the Zealandia sanctuary.  I enter Zealandia, through the visitor centre and predator-proof fence and walk along the green waters of the lower reservoir.  This reservoir supplied Wellington’s water up until 1992, when it was decommissioned because, um, it sat on the fault. The water level is considerably lower than it used to be but there’s still a big sign on the carpark fence in front of the reservoir advising people to stay away from the area in the case of a strong earthquake.  When the reservoir was built in the 1870s, there was limited understanding of how earthquakes were caused.  But it seems odd that it was still used as late as 1992.

Kaka

Kaka

I stop to watch the kaka at the feeders, swooping onto them and clanging them open, holding the nuts in their claws to crack them open.  I love their uncouth and raucous nature , even when they wake me up before dawn.  Above the kaka feeders is a concrete dam holding the upper reservoir, built in 1906.

Upper dam, Zealandia

Upper dam, Zealandia

From the upper dam, I follow the ‘faultline walk’ – a path that runs along the edge of the upper reservoir and follows the faultline all the way to the predator-proof fence at the edge of the Zealandia.

Tui

Tui

During the whole length of the walk, there and back, I see not a single other person.  But I do see lots of birds: saddlebacks echoing harsh calls back and forth through the trees, a little robin picking through the leaves I have kicked up, the rush of tui wings overhead.  A vivid yellow and black stitchbird appears when I sit down to eat a sandwich and at one point a fantail nearly flies into me.  The track runs along the Kaiwharawhara stream full of tangled supplejack, edged with tree ferns.  The ground is soft underfoot, dappled with sunlight and strewn with the dead fronds of tree ferns.  I pass fern-filled miniature waterfalls, their waters trickling over the path and down to the stream below.  The tuis are piping away peacefully to each other, three notes descending in thirds, the last note soothingly repeated.  My route for the day ends at the fence.  I peer through the mesh to see where the faultline goes next, but I can’t tell.  I turn and retrace my steps out of Zealandia, pleased to have the cold wind at my back.

faultline crop

References

GNS Science, Wellington Fault

Grapes R (2000) Magnitude 8 Plus: New Zealand’s biggest earthquake

Te Ara – the encyclopedia of New Zealand