Volcanic

A decade or so ago we’d just signed a binding contract to buy a house in Ohakune when the alert level for the volcano that looms over the town was raised. Last week, for the first time since such levels were introduced, it was raised for the volcano that lies under New Zealand’s largest lake, Taupo. We had a weekend in Taupo planned. I’m beginning to think they’re out to get me.

Lake Taupo

Volcanic alert levels are vague, to say the least. As described by New Zealand’s geological hazard agency, GNS Science (GeoNet), there are six of them, the lowest being zero (no idea why they don’t start at one), which is officially described as No volcanic unrest. This generally means a volcano is dormant, although there’s no such thing as an absolute. A volcano can always come back to life, but zero often means it’s been so long since it did anything that no one alive has witnessed it. In Taupo’s case it was a couple of centuries ago, before a human foot had been set upon these islands. Mind you, it was the most violent eruption in the world in the last five thousand years, pumice deposits from it still exist today in all major river valleys in the area, and the ash cloud blotted out the sun to the extent that China and Italy recorded its effects as unusual sunsets.

Alert level one, which Taupo now sits at, is Minor volcanic unrest, further described on GeoNet’s webpage as Volcanic unrest hazards, which I think means the same thing. There is a long list of these hazards and I encourage you to view their webpage, which is quite fascinating, if you are interested. In layman’s terms it means that a sleeping volcano kind of snorts, wonders if it can be bothered to wake up, decides it can’t and rolls over and goes back to sleep.

Swans, not ballistics

Ruapehu, the volcano that towers over Ohakune, last erupted to any great effect in 1996, with a couple of smaller eruptions fifteen or so years ago. Earlier this year it spent a few months at level two – Moderate to heightened volcanic unrest, or Volcanic unrest hazards, potential for eruption hazards. Level two is a bit of a belch as the volcano is deciding whether to wake or not, possibly followed by a full-on burp, the sort any boundary-searching toddler would be proud of. There probably won’t be lava, but there will be a lot of very hot steam and ash clouds – pyroclastic density currents – and possible projectiles in the form of ejected rocks (ballistics).

No one living near Ruapehu, including us, noted any activity while it was at level two (and it is now back to one). But it can be serious. Unlike Ruapehu, Whakaari/White Island ejects steam almost constantly and was at level two in 2019 when it erupted, killing twenty-two people, mostly tourists, injuring many more. I’ve walked on Whakaari, marvelled at steam hissing from fumaroles, spied the crater lake through clouds of steam, never thought about the inherent danger of standing on a very obviously active volcano.

New Zealand sits on unstable land, prone to minor ground tremors daily (a small shake last week went on for so long we wondered where had copped it badly – thankfully the epicentre turned out to be well underground and no damage was reported). We marvel at the evidence that we all live on a giant molten ball with a fragile crust, stand in awe as mud pools gurgle and plop, sit in bath-warm pools fed by natural springs. It’s all a gamble. Nature is in charge and the earth doesn’t wait for permission to blow off steam; a volcano doesn’t need an alarm clock to wake up.

We had a lovely weekend around the lake that fills the caldera of a near-as-you-can-get-dormant volcano, which showed no signs of the apparent activity beneath. Steam rose from the nearby geothermal works that harness the energy under our feet, providing power for our use. We looked across calm waters at a different side of our mountain, its summit – not as white as we’d like it to be at this time of year – bright against the sky, the surface of the lake silvering in a sun filtered by fine high cloud. We cycled and played mini golf, managed not to brain ourselves or anyone else playing disc golf (we’re new to that) and ate at some lovely restaurants. We didn’t think about whether we’d be blasted to smithereens by a sudden eruption. If a volcano wants to wake up, it will do so, and my worrying about it will make no difference.

Ruapehu across Lake Taupo

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