Earthquake

Woke on Saturday at 4.38 am with the bed swaying about, which it did for ten seconds before settling down, so I scribbled the time on a scrap of paper next to the alarm clock and went back to sleep.

But at breakfast there was an excited reporter telling the nation that Darfield had experienced the biggest earthquake since Inangahua in 1969. It struck at 4.35, and therefore took 3 minutes to travel the 260km to my house.

I had a look at a map: Darfield and Christchurch are two points of a triangle (obv.) and Mr Knight, member of the Diaspora, lives twenty miles away at the third point in Rangiora.

His phone was engaged so as a matter of course I dug out his sceptical email of last week

Sent: Monday, August 23, 2010 9:55 AM
Subject: Re: earthquake
I have yet to feel *any* earthquake here yet. I fear they are a myth, a bit like that global warming that those greenies started. Incidentally I hear that the Tasman glacier calved the biggest ever iceberg this weekend..

and replied

Sent: Saturday, September 04, 2010 8:46 AM
Subject: Re: earthquake
So... erm...

- La. - he promptly phoned, telling me that - inferring, that is to say, certain things about my parents' marital state.

Steph and the Knightlets, near Rangiora (All pics by Bob Knight)

He told me one of the fields next to the river has dropped a metre, and the river has dropped into it so it's now a lake. The bridge he cycles to Christchurch over has been damaged so they'll almost certainly close it, and he says it's likely the only contact with the city will be over the motorway bridge - not much use on a bicycle. - Otherwise he said they were fine; all the books fell off the shelves; kids very frightened, immense noise like a train going past, eight loud and shaking aftershocks of 4 - 5 on the Richter scale, but surprisingly no broken glass in his house and no visible damage, and his water supply was okay. He told me the sky was full of helicopters.

Later, I had an email:

Sent: Saturday, September 04, 2010 11:29 AM
Subject: Re: Earthquake
Now then, just got back from a walk into Rangiora town. No visible damage in the immediate area, however people are panic petrol buying - the queues are at least 10 vehicles long in either direction. This will mean that the petrol will run out which will trigger more panic buying elsewhere etc. exactly what happened in Ingerland some years ago: there wasn't actually a real shortage of petrol but the perception and the panic buying really did make a shortage. I witnessed one incident of mild petrol pump rage when somebody jumped the queue by manipulating the give way rules to jump ahead at the entrance.

More later

Bob

And indeed more did come later, a total (so far) of 64 aftershocks of about 4.6 - 5.2 on Mr Richter's scale:

Sent: Saturday, September 04, 2010 5:17 PM
Subject: earthquake

Ooh, just had another big after shock, just before 5pm. I went out for a ride at lunchtime to survey the local damage. Rangiora has got off exceedingly lightly. We have a few burst water mains, but we still have water and we still have electrickery. What we don't have is food in the shops or petrol after all the panic buying. I set off south east through Tuahiwi and towards Kaiapoi. Just through Tuahiwi I came upon the first crack in the road across a field through the road and into the other field, probably about half and inch wide and with about the same vertical deformation. I got very excited and stopped to examine it for some time. I then continued to Kaiapoi and began to understand the real damage that had happened. Kaiapoi has suffered very badly indeed. There are lots of fallen chimneys through roofs, lots of walls and a few complete structures down; there are many wide and deep fissures in the ground, some are wide open and some are closed, and high ridges have formed across roads. All the bridges across the Kaiapoi river have significant damage, it appears that the river is now slightly narrower than it was before and the bridges have buckled upwards or snapped completely. There is evidence of serious liquifaction everywhere. Kaiapoi sits at the junction of three rivers and has a high water table and there is silt and sand all through the town centre. Kaiapoi has no water or electricity. The largest vertical deformation I saw was about 1 metre and the widest fissure about the same. I continued south to see if the old Waimakariri bridge was open or not. This is the only way of (Ooh another big one just then) cycling to Christchurch and is my life line. It was open but now has a step to get up on to it. Either the bridge has gone up or the river bank has gone down. The railway line alongside now looks like spaghetti, what was once straight is now buckled and distorted beyond belief.I got home and grabbed Steph and the kids to go rubber necking in the car, I wanted them to see the mess before the cleanup starts. We took some amazing photos which I'll send on later. I don't have the camera here, Steph still has it around a friend's house.

More later

Bob

Footbridge, Kaiapoi

Naturally the politicians all came on air to tell everybody the obvious, and the police declared a curfew ostensibly to stop people wandering under unsafe buildings but quite possibly with a view to stopping them inserting their hands into unsafe shop windows and withdrawing souvenirs like plasma screen TVs.

This morning I phoned to see how they'd got through the night - there were 22 aftershocks of around 3.8 to 5.1 between 9 pm Saturday and 9 am Sunday - and demanded all the photos.

Uplift; Knightlets to show scale

As you see, the photos arrived, along with a note about the soil liquification.

Sent: Sunday, September 05, 2010 2:47 PM
Subject: liquefaction
I have been surprised by the amount of sand and silt that has bubbled up from the ground around most of the large cracks and fissures. I'm pretty sure that this is because of the wet nature of the ground that Kaiapoi is built upon, but I don't know if this has contributed to the extensive damage that Kaiapoi has suffered or not. Here's some photos of the silt that liquefaction has bubbled up. I also saw evidence of sewers that had been forced upwards by the same mechanism, the covers standing proud of the road surface by 200mm or so.

Silt volcanoes, result of soil liquification

This is of course mildly off-topic, so we shall try to return to the altogether more fascinating subject of how to make a bicycle go a fifth of a mile per hour faster.