On Tuesday I posted some pictures of New Zealand’s Tolkien-ish landscape. There are reasons why it’s so rugged. And at 10:36 last night, 3 July, one of them happened. New Zealand’s North Island was rocked by the biggest quake it’s had in many years.
It shook Wellington like a terrier rattling a bone. Listen for yourself – here’s the noise it made in a Wellington church during a recording session. The quake starts around 00:45: http://www.stuff.co.nz/national/7219667/Earthquake-captured-on-organ-recording
I was asleep when it hit, blasted awake by the jolt – and wondered whether it was local. There wasn’t any sound of stuff crashing around the house so – well, I went back to sleep. Hey, we’re used to these things. We’re prepared. It was nowhere near as sharp as one in December that caught She Who Must Be Obeyed and me in a masonry building (we dived under a table).
My personal ‘felt estimate’ for the intensity around our house was around IV/V on the Modified Mercalli scale (building creaks, dishes and plates rattle, people woken). But I wanted to know the absolute magnitude and epicentre. New Zealand has a fantastic seismic network. Our Geological and Nuclear Sciences department posts early estimates in near-real time. By the time we were up at 5.00 am this morning (discovering nothing dislodged around the house) they had a final figure for the quake and its location. It was a big one; magnitude 7.0, luckily off the Taranaki coast and very deep. Probably the Pacific plate moving.
A happier Christchurch – a picture I took of the crowd at the 2009 arts festival.
It wasn’t expected, but there are several known faults around the country which are overdue to move, including one that will trigger the ‘big one’ in Wellington – a quake of 8+ magnitude with a likely ‘felt intensity’ of X on the MM scale. The lesson was brought home when Christchurch was devastated by a succession of quakes beginning in September 2010 – including one in February 2011 that killed 182. The official enquiry into why buildings collapsed is under way now.
There is a theory that the Christchurch sequence was triggered by a 7.8 magnitude quake that hit Fijordland in July 2009. It did no great damage in that remote location but seems, some geophysicists think, to have stressed the system – which then fractured in Christchurch. Whether the latest quake is going to do anything on the Wellington system is a moot point. GNS said today they haven’t the resources to look further into it just now.
But, to me, not it’s something to lose sleep over. We have to live with quakes, here in New Zealand. And volcanoes. And pointy sticks.
Well, actually not the pointy sticks. But definitely quakes and volcanoes. They’re gonna happen – we have to accept them. And be ready.
+++Coming up: a contest. Watch this space.+++
Copyright © Matthew Wright 2012
Holy cow that was scary sounding! I had no idea what to expect, having never been in an earthquake. Thanks for the link.
I’d never heard of the MM scale before. That puts it into perspective.
I know it’s redundant, but Matthew, STAY SAFE!
Thanks! The MM scale is maybe better than the old Richter figure because it gives the human aspect, which varies depending on distance, geology etc. The main headline in today’s morning paper indicates Wellington would be cut off and otherwise in trouble for four months in a major quake. There’s also a high chance of tsunami on top. The key is being prepared – in our household we’ve got a comprehensive emergency kit, including water. That’s the crucial resource. It rains incessantly in Wellington, but never at the right times. If mains power is available I can boil river water or run dehumidifers and drink what’s collected, but I guarantee power’s the one thing we won’t have. Maybe for weeks.
There is a certain level of fatalism in all this – it’s not ‘if’, but ‘when’ – the science of what’s going on is clear. Which means not just having the right emergency gear, but also thinking about what’s likely to happen – including the possibility of being a casualty – and being ready with a plan to cover all the likely eventualities. We have one. I am not 100% sure that all other Kiwis do (but a LOT do).
My great-grandfather served a mission to New Zealand from 1889-1891 and mentions being almost shaken out of bed on Nov. 19, 1891 by a series of shocks. He counted 24 during the night and said at one point the earth waved just like the sea. He was staying in Otaraminia(?) and several locals told him an island had blown up and great clouds of steam and smoke were coming out of it.
It was a classic colonial experience – I’ve dug through the archives and found similar accounts which build a picture of a very seismically active landscape. But it seemed to quiet down in the early twentieth century, causing scientists of the 1920s to officially suggest that earthquakes in New Zealand were an academic issue. Boy were they wrong – though, of course, the mechanisms that actually cause our quakes were not understood until after the 1960s.
That is a very interesting point. Ever since the Canterbury quakes we all nod our heads and throw scientific terms around like experts (kind of like when everyone in New Zealand became a sailing veteran when we won the America’s Cup), yet curiously much of that understanding is lost within a generation or two.
As you say, the 1840′s-60′s gave settlers a very clear picture of just how volatile the earth can be but that was seemingly shelved in the back of the populations minds until the late 1920′s-40′s. It almost feels like we have made that mistake again, and only now having experienced the devastation firsthand does the risk become a reality instead of just a photo we saw in a book some time. I wonder if the same thing will happen again in the 2090′s.
I just hope we don’t all become experts on volcanoes or tsunamis any time soon.
So do I. Auckland is sitting atop a lava field. Hmmn… You’re right – these events thrust such disasters to the popular forefront. Next week there’s somethng else to draw attention. Unfortunately the natural processes driving our tectonic adventures aren’t so co-operative.