Meeting point: tectonic plates collide in dramatic fashion at Gaunt Creek. Photo / Alpine Fault Tours
Meeting point: tectonic plates collide in dramatic fashion at Gaunt Creek. Photo / Alpine Fault Tours
In an edited extract from his new book Down South, Bruce Ansley puts his life on the line and follows the Alpine Fault
The Alpine Fault runs northeast from the northern side of the entrance to Milford Sound, through the mountains behind Martins Bay, along the coast beneath the Southern Alps to Hokitika, its route marked by escarpments so clearly that in winter the snow seems to have painted it with a brush. Turning inland, the Alpine Fault runs to a point near the Lewis Pass, travels northwards then frays into four main faults that extend to the east coast. On a map that cluster of fault lines looks like a bed of snakes that, when poked, turn deadly. They move at a speed of 38 millimetres a year, which to a seismologist is like the speed of a Ferrari Testarossa on a test track. This makes them extremely dangerous.
The Alpine Fault last got seriously testy in 1717 or thereabouts and before that, in descending order, 1620, 1430 and 1100. Those dates were shifting as scientists re-calculated, but in terms of simple arithmetic, they mean that New Zealand is due for something very dangerous right about, well, now. Seismologists expect the Big One to dwarf all opening acts.
I decided to take a closer look at that deadly latticework.
Earthquake country: the deceptive calm of the Alpine Fault mirrored in Lake Matheson. Photo / Gerhard Zwerger-Schoner, Getty Images
The Wairau Fault runs along the Wairau Valley from Renwick near Blenheim to the Nelson Lakes. I travelled south from Cloudy Bay, with my fingers crossed. I'd endured thousands of earthquakes in Christchurch and didn't trust whatever celestial bean counter was keeping tally. Torn up by the traffic diverted from the coastal route, the road through the valley was rough and lonely. Wairau Valley was the centre of civilisation here, school, memorial hall, church, fire station, golf course and a pub that had served travellers for more than a century and a half. I was an early-morning traveller, and the pub was closed.
So was the town, apparently. Very little happens here and, given its dangerous location, locals like it that way. When the main street got a footpath a few years back, the story made the newspapers.
Following the fault line for one hundred kilometres, I reached Lake Rotoiti, that perfect, narrow little lake squeezed between mountains with St Arnaud at its head. I thought the town of St Arnaud lay perilously close to the fault line. I was wrong. In fact, like Franz Josef far to the south, St Arnaud actually straddles the fault line, possibly one reason why it is New Zealand's least-known alpine resort.
Tectonic: the Wairau Valley straddles both tectonic plates. Photo / Nazar AB, Getty Images
A strong quake here would not only sever this poor, hard-pressed road, it would cut every surrounding road and cause landslides that would likely lift the lake itself, flooding the shoreline and possibly the town, and sending a wall of water down the Buller River. A few kilometres north of Murchison I walked up the Matiri Valley to Lake Matiri, which I'd never heard of before, much less been to. The walk was gentle, considering the earthquake-riven country all around it. It took me through beech forest to a lovely little hut on the edge of the lake, where I sat on the porch and contemplated the still water below and the mountains and the peace. The spectacular scenery came courtesy of the Alpine Fault. All around were the scars of rockfalls and slips and landslides, one of which had created the lake itself.
No one needed any convincing about earthquakes in Murchison. On June 17, 2019, the town remembered the magnitude 7.8 earthquake that had struck at 10.17am exactly 90 years before. Seventeen people died, 14 of them killed by landslides. It was New Zealand's third-worst earthquake tragedy, after Napier and Christchurch.
Shook up: Hampden Hotel in Murchison, and site of New Zealand's 1929 quake. Photo / David Wall, Getty Images
Fewer than 500 people live in Murchison now. To me, after more than half a century's passing acquaintance with the town, it didn't seem to have changed much. The old Hampden Hotel (Hampden was the original name of the town when it was founded following a gold rush) still stood on its corner, its splendid verandas as close to pristine as old pubs could get. The old stables, St Paul's Church, the picture theatre, the council chambers and the post office still existed, even if their uses had changed a bit. The town still possessed the best junk shop in the South Island and its general store, Hodgson's, might have been a museum piece if it wasn't so ... useful. The French pastry shop hinted at another life. So did the courthouse, which once presided over New Zealand's and possibly the world's first suicide bombing.
Monuments to the 1929 earthquake were everywhere: slips, rocks, lakes, mountains hammered to pieces, landscapes battered into bits. I walked up a track in the Matakitaki River valley near the town. It emerged at the bottom of a huge slip triggered by the earthquake. As I went higher, the terrain became more sculptured: giant blocks of rock as smooth and straight as if they'd been cut by some celestial stonemason and fashioned into arches, rectangular ashlars, capitals, flagstones, pillars, blocks, orderly forms in disorder, a ruined city of rock in perfect shapes lying beside cliffs that seemed to have been carved from the landscape.
I took the road west across the Maruia River, past the old town of Lyell, once the site of one of the country's biggest goldfields, twisting along the Buller River to Inangahua Junction. It's called a junction because the railway line from the north, the fabled Nelson Line, was supposed to meet the western Stillwater to Westport Line right here. The Nelson Line was never finished, a controversial subject still.
On May 24, 1968, at 5.24 in the morning, an earthquake struck the area. It was rated X on the Mercalli scale, which meant it was very destructive; the 2011 Christchurch earthquake was only VI.
At fault: a visitor places a finger at the point where the tectonic plates divide. Photo / Supplied, Alpine Fault Tours
Inangahua then was three areas: the township of Inangahua, Inangahua Junction, and Inangahua Landing beside the river. The junction was worst-hit. The town's old hotel was destroyed by a slip that also pushed houses off their foundations and crushed buildings. A vast landslip blocked the mighty Buller River, creating such a lake the authorities feared it would burst and flood both Inangahua and Westport. Both towns were evacuated and many never returned to Inangahua.
When I visited, nothing was moving in Inangahua. Of the 144 people reputed to be still living here, there was no sign. The cafe was closed. The "Historic Lyell" display in the museum, the old town hall, was closed. The abandoned church was for sale. Gardens were tended and (some) houses painted, but of the gardeners or any kind of citizenry there was no sign.
I drove through Reefton to Greymouth then south, stopping at Whataroa.
I wanted to go to a spot called Gaunt Creek. This place is unique in the world, for there you can actually see the fault line, see the two tectonic plates pressing together, the Australian Plate nudging the Pacific Plate. Imagine the tremendous forces at work, shifting the Earth's crust, two colossal bodies springing against each other.
Gaunt Creek's contribution to the geological trove is the fact that, there and nowhere else, a slip has exposed the fault. At Gaunt Creek you can stand with a foot on each tectonic plate so that you straddle the two worlds, hoping, of course, that the Big One will not choose that exact moment to strike lest your stance became a little wider than physically desirable.
Four centimetres a year: a survey station is swallowed by the Gaunt Creek fault line. Photo / Supplied, Alpine Fault Tours
The site is on a farm so on this chilly day, I went into Whataroa, hopped on to a little green and cream bus with the driver, Elisabeth, and her two children, Victoria and Archer, drove past a curiously named feature, Ralfes Knob, and headed up the beautifully named Waitangitaona Valley. We drove along the tawny valley floor, the dense West Coast bush pressing down the mountainsides, then sidled off along Gaunt Creek, which wasn't gaunt at all, really, just a stream cutting through the layers of glacial gravel.
I studied the fault line from the opposite side of the creek, which overnight rain had made a little high that day. It was a gash of minty green cataclasite, or fault rock, against a sharp line of brown glacial gravels in a grey landscape, the kind of thing that, had you not known of its significance, you might have looked at, wondered about for a moment or two and moved on. Yet this was the collision point between two vast plates, where anybody, not just a geologist, or a scientist of any kind, but any simple Joe could actually see what all the fuss was about, even sense the forces.
Heaven and a few geoscientists only knew what this place would be like in a decent shake. Gaunt Creek had been like this, more or less, since the last huge quake in 1717. It was time for another bang, and the probes here might at least give notice and, come the calamity, offer the opportunity to study the mechanics of an earthquake from the inside, learn how the fault worked and about the arrival of the beast, rather than simply measuring the aftermath.
This was one of the most exciting places in the world for a seismologist. I walked through gorse while far below my feet millions of years of intercontinental drift were at work. Yet up here it was silent and all seemed so peaceful, so innocent. We drove out over the fault line, which, I now knew, was diving below us at a forty-five-degree angle.
Down South by Bruce Ansley, published by HarperCollins New Zealand, is on sale now.
Alpine Fault Tours take visitors to the fault line at Whataroa. See alpinefaulttours.co.nz for more information.
