EaRtHqUakes!
Posted: 08 February 2012 12:57 PM   [ Ignore ]
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Hi all!

Most of you will probably be aware of the earthquakes that have been going on here in Christchurch, New Zealand since September 2010.

I thought I’d start a thread about it since we’ve just passed the 10,000 aftershocks mark!

I’ve been fortunate enough to still have a house but many people I know do not.

In the small hours of September 4th, 2010, I woke up to a rumbling sound, followed by shaking. At first I thought it was just one of our smaller shakes - not that we were “known” for our rumbles but we might get the occasional 3.something that gets people talking. But this one just grew and grew. I leapt out of bed and headed for the doorway and actually had to hold on to it to prevent myself from falling over. When I heard stuff smashing downstairs I knew it was a biggie.

Fortunately we didn’t lose power, phone or internet, so I was able to communicate with people fairly easily. I soon found that we’d had a mag 7.1 slightly out of town.
Also fortunately, there was NO loss of life. Sadly, many homes and businesses were lost.

Christchurch is built on old wetlands. In fact, I suspect that if they knew what was down there, nobody would have settled here.
In some areas liquefaction was really, really bad. In short, liquefaction silt & water spewing out of the ground and it looks like this.
Areas that are close to rivers got hit quite bad, and areas built on the more swampy ground were totally inundated with it.
And of course, the displacement of that silt means the ground actually sinking quite a bit. We have almost entire suburbs written off and there’s places that we will NEVER be able to build on again. A few in particular should never have been built on in the first place as the risks were known.

Over the following months the aftershocks subsided slowly, but we still had some pretty scary ones.
Boxing day was ruined by a large-ish aftershock that closed down businesses on their busiest day of the year.

All seemed to be getting better until February 22nd, 2011… 12:51pm to be precise.
A 6.3mag quake, located this time in Lyttelton harbour, an extinct volcano that we are built next to/on.

While 6.3 might sound a lot less than 7.1, it’s force was unprecedented. As Wikipedia says…

The quake was a “strike-slip event with oblique motion”—mostly horizontal movement with some vertical movement —with reverse thrust (i.e. vertical movement upwards). The vertical acceleration was far greater than the horizontal acceleration. The intensity felt in Christchurch was MM VIII. The peak ground acceleration (PGA) in central Christchurch exceeded 1.8g (i.e. 1.8 times the acceleration of gravity), with the highest recording 2.2g, at Heathcote Valley Primary School a shaking intensity equivalent to MM X+. This is the highest PGA ever recorded in New Zealand; the highest reading during the September 2010 event was 1.26g, recorded near Darfield. The PGA is also one of the greatest ever ground accelerations recorded in the world, and was unusually high for a 6.3 quake and the highest in a vertical direction. The central business district (CBD) experienced PGAs in the range of 0.574 and 0.802 g. In contrast, the 7.0 Mw 2010 Haiti earthquake had an estimated PGA of 0.5g. The acceleration occurred mainly in a vertical direction, with eyewitness accounts of people being tossed into the air. The upwards (positive acceleration) was greater than the downwards, which had a maximum recording of 0.9g; the maximum recorded horizontal acceleration was 1.7g

I’ve never felt anything like it and hope I never do again.

I was at work at the time. One sales rep who was on the road at the time said he saw cars actually leave the ground! big surprise
I don’t drive, I cycle everywhere, and I’m glad I do - it was the best way to get anywhere! The streets weren’t only clogged with people trying to get home and to loved ones (most phones were out) but the roads were rough at parts too.
The second aftershock came as I was on my bike… not nice! Picture someone pulling a sheet around underneath a cat and you’ll get the general idea of what the sensation might be like.

Here is some CCTV footage of the quake as it happened. I was nine minutes away from walking into town on my lunch break and this is the route I planned to take!! Sure glad I’d been held up by a sales rep.

This time we weren’t so fortunate. 184 people died. Three of them I knew. One of them, Matty Beaumont, was in the Canterbury Television building where half of the deaths occurred. There was no “body” to speak of and it took weeks for him to be formally identified. The building was weakened by the September quake and concerns were raised about the safety of the building.

Thankfully we have very strict building codes so we still have a city!  While the news footage overseas probably died off pretty quickly, we’re still in recovery mode and I don’t think we’ll know “normal” for years to come. The central business district is still fenced off as they take the larger buildings down that are in bad shape.

It doesn’t end there though. We got hammered again in June 2011 by a 6.0, and again in December by a 6.0. I was again on my bike for the December 6.0 and that was pretty scary. Thankfully, while there was still damage, there was no loss of life.

Naturally, these disasters haven’t been without conspiracy theories and such silliness. I’ve seen people posting all sorts of piffle on the net. HAARP, chemtrails, and we have our resident “moon man” who thinks he can predict quakes as well as weather by the moon. Despite his spectacular failures, people still get scared around the full moon. An co-worker of mine sometimes left town during full moons… and of course nothing happened. I understand people’s anxieties though.

Here’s my pics of quake damage:
February 2011 quakes: https://www.facebook.com/media/set/?set=a.10150104940587226.286585.589507225&type=3&l=0c98991c8e
June/December 2011 aftershocks: https://www.facebook.com/media/set/?set=a.10150215195852226.331163.589507225&type=3&l=010d4317a4  (some pics of my mother’s house that was written off in there.)
September 2010 quake: https://www.facebook.com/media/set/?set=a.431187992225.229801.589507225&type=3&l=799019d5bf

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Posted: 08 February 2012 01:05 PM   [ Ignore ]   [ # 1 ]
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Oh, and here’s an animated quake map to give a good idea of why so many of us were at the end of our tether…

September: http://www.christchurchquakemap.co.nz/all
February (wait until 12.51pm): http://www.christchurchquakemap.co.nz/february

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Posted: 08 February 2012 02:20 PM   [ Ignore ]   [ # 2 ]
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King;

Hope you and all your friends are unharmed.  In the Buffalo NY area we don’t have much experience with earthquakes.  Nothing major in our memories although e set on the Niagra fault.

  Let us know if there is anything we can do.

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Posted: 08 February 2012 07:03 PM   [ Ignore ]   [ # 3 ]
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Thanks Gary. Appreciate the comment.

It’s just one of those things we’ve got to work through as a community.

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Posted: 08 February 2012 08:51 PM   [ Ignore ]   [ # 4 ]
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Those are some incredible images on your facebook page.
It’s impossible to grasp what it must be like to watch your community be rattled to rubble.

And the http://www.christchurchquakemap.co.nz/all is a mind blower, that really brings home what’s going on there.

I’ll admit I was only vaguely aware that some Earthquakes had occurred in New Zealand -
but had no idea it was a pandemic.  It’s so weak to say my heart goes out to you folks and all those platitudes,  but I am in a bit of shock trying to absorb it right now.

I appreciate you sharing

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Posted: 08 February 2012 09:02 PM   [ Ignore ]   [ # 5 ]
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What a shame,Christchurch (and New Zealand as a whole) seems like a very nice place to live.

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Posted: 08 February 2012 11:34 PM   [ Ignore ]   [ # 6 ]
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I’ve grown up In California so I’ve experienced one every two or three years.  Most are mild, but every once in a while we have one that really does damage.  However, after about 70 years one gets used to them and is happy that we don’t have to face tornados or hurricanes.  However, I can sympathize with you, King, because they can be extremely destructive and quite unnerving.

Occam

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Posted: 09 February 2012 06:27 AM   [ Ignore ]   [ # 7 ]
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King, I hope you and yours stay well also. Also, I’ve enjoyed your input to this forum.

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Posted: 09 February 2012 07:12 AM   [ Ignore ]   [ # 8 ]
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Thanks for letting us now this. Here in the U.S. we heard about the Sept. 2010 and the Feb. 2011 earthquakes. I had no idea of the repetitive aftershocks. Keep working together down there and you’ll pull through. Do any scientists have a clue how long this is going to continue?

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Posted: 09 February 2012 12:29 PM   [ Ignore ]   [ # 9 ]
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Thank you very much for the kind words people!

DarronS - 09 February 2012 07:12 AM

Do any scientists have a clue how long this is going to continue?

It’s been a very tricky job for scientists here. Not to mention stressful, some of them are working through this will suffering their own personal losses. We’ve had a lot of international help from the scientific community and as a result I think the WORLD is learning quite a lot about earthquakes.  After the Sept quake more sensors were put in place so they have learned a lot from studying the many aftershocks - this will give other countries something to learn from. Our readings are more accurate as a result. That’s something Haiti didn’t have.

It’s certainly got the rest of the country looking at building standards, particularly with older brick buildings with fancy masonry - they’re the ones that fell into streets and crushed people to death. Our capital city, Wellington, sits directly over the Alpine Fault line is of particular concern.

The Sept quake was caused by the Greendale Fault - which was previously unknown until that morning. We always knew the Alpine Fault was going to be the cause of the “big one” as it’s caused some major quakes in the past so it was a bit of a surprise. If you look at a satellite image or topographical map you’ll see that it formed our Southern Alps.

There has been some thorough mapping of our faults and evidently there’ a LOT of them, though they’re supposedly smaller. Just out to sea, east of Christchurch, there’s a few of concern, but they don’t think they’d produce quakes much bigger than 6.0 and they’re not a tsunami risk. The aftershock sequences have been as expected, but these newly discovered faults have complicated things. Finding the faults is one thing - predicting quakes though, as we all know, is impossible. We don’t know the age of them and we don’t know when they last ruptured.

After the bigger quakes, I could expect a good dozen aftershocks per day, but now I can go 2 or 3 days without feeling one. Not that they’re not happening, they’re just smaller and less frequent. There’s the occasional cluster though.

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Posted: 09 February 2012 02:57 PM   [ Ignore ]   [ # 10 ]
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I forgot to mention that Univ. of Buffalo has an earthquake center.  I don’t know how much help it will be in your current situation, but here is a web page:

http://nees.buffalo.edu/

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