Seismic Night, Holey Night….

“You could see the panic on people’s faces. That’s the end of Christmas – it’s so unfair,” Sue Joy, florist  23 Dec 2011 

On the eve of Christmas Eve, just when things seemed to be all calm and all bright, the serious jolting started again.  Not only shepherds  were once again quaking at the sight of the quakes. No seismic Christmas truce here in Christchurch in the demolition  trenches  but lots of new sink holes- and a sinking feeling. 

As I write this, at 8am on Christmas Eve, GeoNet has reported 63 earthquakes around the wider Canterbury region over the last 24 hours.* This ended six months of relative calm for the city and will further set back  recovery as insurance companies re-start their risk raters. 

Christchurch residents hoping Christmas celebrations would be a brighter end to a bleak year are instead dealing with more seismic damage to homes, infrastructure and businesses through shaking damage and liquefaction.

Two large magnitude earthquakes on Friday heralded the new activity – a Richter 5.8 and a 6.0, the latter being the 4th largest magnitude since the seismic season started here in September 2010. 

I was upstairs at home for the first 15-20 seconds roller and was out in the garden for the second shorter, but more feisty shock, talking to our Student Job Search gardener who was just describing how he’s seen our whole house jiggle at the earlier quake when we had an even jigglier encore.

Our post World War II rough hewn rimu house is obviously very elastic and goes with the flow. It probably also helps that it is sitting on a foundation of crusher dust from the old Halswell Quarry across the road which acts like base isolation. The grandfather clock downstairs and the cuckoo clock upstairs kept going through the first but were stopped dead, but ever to go again, by the second. 

Once again we were fortunate but a lot of people, especially on the east side of town, were not with power cuts and liquefaction silting up  parts of the eastern suburbs for the fifth time in 15 months.* Not the Xmas present they were expecting. There appears to have been a Mercalli migration further east. Most of the recent quakes were centred in faults below Pegasus Bay, off the coast of Christchurch, within 8-21 kilometres of the city centre, and many were less than 10km deep. 

Whatever the new physical damage from these earthquakes-and there were scores of minor injuries-  they have further set back the recovery of the city. Retailers who have struggled to survive were dealt a major blow as stores packed with Christmas shoppers were evacuated. Some face being shut on the busiest trading days of Christmas Eve and Boxing Day. 

 Essential tremor 

“Essential tremor” is an involuntary trembling that affects millions of people. In October 2008 Eddie Adcock, 70, a bluegrass maestro whose career was being hampered by a hand tremor was asked to pluck his banjo during brain surgery, so surgeons could pinpoint the right part of the brain to work on. During the procedure surgeons prodded and inserted electrodes into his brain to suppress the nerve cells causing his tremors. When the surgeons found the right part of the brain, the plucky Adcock instantly regained his ability and was able to play at full speed once again*. 

The Canterbury land mass above and below the waterline seems to have developed a chronic case of the sesmic ETs. In this case the geotechnical explorations and explanations can’t by their nature be as precise as Adcock’s half hour. Nor can they give the same instant feedback in any predictive sense, let alone bring about a cure.

For that reason the latest tremors have literally sent shock waves through the psyches of people here who were just starting to relax into the Christmas spirit and contemplate a happier and more stable New Year. For some it was the last straw:
“Had enough now   #52   17 min ago   Thats it. We cant do this any longer, the kids are upset, wife and I cant sleep, the best of the city is gone, we are going too. Sorry to those we are leaving behind to rebuild and tough it out. Family and prospects in Melbourne.*” 

But most, not so badly affected, will stay and hopefully display the spirit and dogged determination needed by new pioneers. Before this latest blitz about half the commercial buildings in the central city have either already been demolished or are about to be, including our former offices. There could well be some new candidates.

This Yuletide in this part of the world it’s just got that much harder to sleep in heavenly peace. But many of us still have a lot to celebrate so best wishes for the festive season, no matter how restive. 

*Blinks
http://www.carols.org.uk/silent_night.htm 
http://www.canterburyquakelive.co.nz/
 http://www.stuff.co.nz/national/christchurch-earthquake/6186421/Christchurch-continues-to-rattle
http://www.stuff.co.nz/national/christchurch-earthquake/6185073/Residents-left-scared-and-emotional
http://www.stuff.co.nz/national/6185025/Tremors-will-last-for-some-time-GNS-says 
http://www.stuff.co.nz/oddstuff/675837/Banjo-master-plays-during-brain-surgery 
http://www.stuff.co.nz/national/6186421/Rattled-Cantabrians-hope-for-normal-Xmas
 

#Lyall Lukey 24 December 2011
http://www.lukey.co.nz/  http://www.smartnet.co.nz
https://bluggerme.wordpress.com  My other less serious blog

 

 

 

 

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