Saturday, February 26, 2011

Shaken AND Stirred!

This last week has been full of the horrors of the earthquake which devastated Christchurch, television has been near a continuous wall-to-wall coverage, while the newspapers have constant updates and galleries of searing images.
It has been frightening, on several levels, not least that we live in the Wellington region which is itself astride a very active fault system.
Needless to say it has prompted (certainly well-overdue) reviews of our emergency preparedness - largely theoretical I'm sorry to have to concede. Of course, Desiree has therefore swung into action, and we now are developing a cache of clothing, blankets, cooking & heating supplies, food, water, etc. in an accessible place. All we need now is to know that the emergency will strike while we're at home!
And then I received a lovely email from a cousin in Canada, with a lovely 'update' photo of their family. In it I was asked if there was any connection between the faultlines near us and those which caused the destruction in Christchurch. Which got me thinking: how to explain our position to someone on the other side of the world?
So have a look at these:

New Zealand lies across the margin of two major tectonic plates - the Indo-Australian (to our west) and the Pacific (to our east). The consequence is that the country is riddled by faultlines, in particular the Alpine Fault, which runs along the 'spine' of the South Island, forming the Southern Alps. It then bends and splinters in a number of smaller faults which cross what we call Cook Strait, to re-emerge in the southern North Island as a series faultlines, which stretch north and become the Volcanic Triangle around the central Plateau and Bay of Plenty.
In our part of the North Island, the major faults look like this:

And how far away are we? Wellington to Christchurch by road is a distance of 414 km (257 miles) and takes about 5 hours, after a ferry crossing of 3 hours. By air it is a 45-55 flight, or there is a scenic train trip which takes about 6 hours, after the ferry trip.
I was reminded that I had mentioned a nearby faultline, which I had shown Erin while she was visiting with us. Again, is it close? Well have a look at this map, and click on the place indicated.

There is a rise in the road, as it goes up to the Hutt Road (look at the path beside the building on the right). That is the fault scarp left after the last major movement on the Wellington Fault, in the 1850s. We used to live with 100 metres of this, although we are now several kilometres away.
There is nothing heroic about it - we just live with it, and hope that when "the big one" strikes, we'll be OK.
Oh, and we visited Christchurch for a few days last March, and had a lovely time in a lovely city. It is saddening to see the same places we remember with affection now rubble and dust.

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