Ever get that feeling of quake deja vu?

Monday was the provincial anniversary holiday in Wellington, New Zealand. Kind of cool – the provinces were abolished in 1876, but we still get the holiday.

Around 4 pm the house began shaking – slowly at first and then quite violently. We get a lot of small quakes. This wasn’t one of them. In fact, it seemed up there with last year’s big quakes.

The science behind it is fascinating. New Zealand has an automated seismic network that publishes estimated figures to the internet in near-real time. The first official figures – calculated by the duty seismologist – were available within fifteen minutes, with a final refined value just over an hour afterwards. This quake, at magnitude 6.2 and with an epicentre near Eketahuna in the Wairarapa, was classified ‘severe’. It was 33 km deep – felt widely, but not so destructive as the shallow quakes that hit Christchurch in 2010-11 and Wellington in 2013. It occurred in the Pacific plate subduction zone, where the plate is being driven down by the Indo-Australian plate riding up over it. It’s no coincidence that this is right under New Zealand – the islands are a product of that collision.

Gollum in Wellington airport passenger terminal - a marvellous example of the model-maker's art.

I don’t have a photo of the Wellington airport eagles, but this is Gollum – taken last year – near the model that fell into the foodcourt. Click to enlarge.

Where I live the ‘felt intensity’ was at the high end of V on the Modified Mercalli scale. Damage around Wellington included the Weta workshop model of a Hobbit eagle  in the airport terminal, which crashed into the food-court. It was worse across the lower North Island in centres like Palmerston North. Fortunately nobody was killed or hurt.

Quakes have been on the rise in New Zealand lately. Archaeological work reveals that quakes cluster in decades-long patterns. The late twentieth century was one of the calmer periods. And now it looks as if we’re back in the action again. Christchurch, alas, may have simply been the beginning. Are they linked? Possibly. Certainly a quake in one area can increase stresses in a fault nearby that’s already under tension. But there also seems to be a general process of rising and falling activity.

The Christ Church Cathedral - icon of a city for nearly 150 years and the raison d;'etre for its founding in 1850. Now a ruin, due to be demolished.

The Christ Church Cathedral, Christchurch – photo I took in early 2013. Click to enlarge.

Best case is it will settle down. Worst case – well, there is a disturbing precedent from the fifteenth century, where a succession of massive quakes estimated at magnitude 8+ tore along the length of the country over just a few decades. One of them, circa 1460, struck just south of Wellington and filled in one of the two harbour entrances, the Te Awa-a-tia channel. Motukairangi island – modern Miramar – became a peninsula and the water within its hills swampy terrain. Peter Jackson’s studio is built on the uplifted land.

It's all in an ordinary industrial-style street.

Warehouses opposite Peter Jackson’s Park Road headquarters, Miramar – under water until 1460. Click to enlarge.

Maori named the quake Haowhenua (‘the land destroyer’). The evidence is still visible as the flat land of Miramar and the Wellington airport flats – and as beach lines at Turakirae Head. The name seemed a puzzle – a ‘land destroyer’ that produced uplift? Then archaeologists discovered evidence of 10-metre tsunamis at the same time.

The question is not ‘if’ this will happen again – but ‘when’. New Zealand has many fault lines – the largest is the Alpine Fault, which moves about every 300 years and generates quakes of magnitude 8+. We are due for one, statistically, within 50 years. Recent studies point to the existence of other large faults each side of the South Island. They are still being researched. Scary? No.  We have to accept the reality as it unfolds – and be prepared.

Do you live in an earthquake zone? If not, what natural disasters do you face?

Copyright © Matthew Wright 2014

Coming up: More writing tips, science geekery and humor. But hopefully not more quakes. For a while, anyway.

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14 comments on “Ever get that feeling of quake deja vu?

  1. Geez, Matt. Seems like you have been getting one every month, though I know that’s not quite accurate.

    As you know we get air temps below zero F for days and weeks at a time. Wind chills in the -40 to -50 F. But, the fun does not stop there. Annual river flooding, tornadoes, straight-line winds, mosquito swarms, drought, and yes, we even get the occasional earthquake. But nothing like yours.

    • The frequency of the bigger quakes is definitely increasing here. The latest on Sunday’s is that our seismologists are looking into potential links with a mag 7+ ‘slow quake’ that took a year to quietly happen. So imperceptible it was only picked up by GPS data on the movements each side of the fault. Now they suspect it may have helped tension the fault that ‘blew’. Interesting and with a likely practical outcome for the science. I hope. Every skerrick of data helps.

  2. We get a little bit of everything here in Oklahoma – tornadoes, the occasional wildfire and blizzard, and earthquakes. All with the craziest temperatures you ever did see. This past weekend we had spring weather. Today, we’re not even making it above freezing. Blah.

    • Have to say that to me a twister sounds way worse than a quake. We get very few tornadoes in NZ and no big ones to US scale. Yeah, the weather’s crazy here too. Not so much global warming as global weather chaos I suspect.

      • See, we at least get warnings that a tornado is possible/imminent. Earthquakes just happen out of the blue.

        • True! Our seismologists do offer probabilities on known fault lines. Alas, the nature of the system means they can’t exactly state what will happen when. And there’s the problem of unknown faults, like the one that livened up under Christchurch in late 2010. Bang! No warning.

          There IS a fellow who claims to be able to exactly predict earthquakes, apparently via mystic moon forces or the etheric effects of Pluto or something. A little while after the September 2010 Christchurch quakes he apparently insisted there would be no more major events, although the seismologists were warning of a high probability of more major shocks.

          What happened? The seismologists were right. There was a major quake. Tragically, it left 185 dead.

  3. Lemuel says:

    My first thought when I saw the photos of the fallen eagle was that perhaps it is a sign that Peter Jackson should produce a remake of ‘The Eagle Has Landed’! It seems a miracle that no-one was underneath the sculpture when it fell.

    I suspect that communities tend to underestimate the potential impact of natural disasters that haven’t occurred in living memory. The Christchurch quakes really gave New Zealanders a shake up both literally and figuratively and as a result we seem much more wary of the risk to other places like Wellington. That risk was always there but it seems ‘more real’ than before. Unfortunately I don’t think we have the same appreciation for just how devastating a major tsunami could be here as we don’t have that same immediate experience as we do with earthquakes – yet the archaeological record clearly shows how vulnerable many of our coastal communities are.

  4. Definitely not the kind of anniversary celebration I’d want! Last big quake in this area was in 1983, measured 7.3, and caused a lot of damage and two deaths in a small town about 150 miles from here. We’re on a different fault and only felt a tremor or two. Of course, we sit on the edge of the Yellowstone Caldera and are not nearly as enthusiastic about its possible future eruptions as some scientists.are.

    • Yellowstone is a pretty scary supervolcano. We have one in NZ too – Taupo. Not great to live nearby and the intervals between eruptions in both places is nowhere near large enough!

  5. jjspina says:

    Here in New England, USA, we don’t have earthquakes very often. When we do have one it is a mild shaking since there is a fault line running through my state of New Hampshire. That still is scary.

    The one that Americans worry about is the San Andreas Fault running through California. There was a strong quake in 1906 and another in the early 1990’s. the next big one may wipe out a large portion of the state. It is a frightening thing and I can’t imagine being in the middle of one and surviving.

    • The San Andreas is definitely a fault to watch – we’re staring down the barrel of the same thing here in NZ with the Alpine Fault, which is similar. And I guess the folks in Indonesia and Japan have the same thing – revealed rather dramatically in 2004 and 2011, alas. Life on the “rim of fire”…

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