Christchurch Earthquake follow up.

[johnr]

In 2011 There was a devastating earthquake in Christchurch.

Many of you will remember this and I remember with warmth the reactions of WG members to this event.

The whole thing was quite quickly overshadowed by events in Japan which were worse by whole orders of magnitude.  The Christchurch event seemed hardly worth the mention in light of the Japan one. But of course to those in Christchurch it remained a very big deal indeed.

Some months earlier there had been what might be termed a 'set up' event.

SATURDAY 4 SEPTEMBER 2010

4:35am (NZ time), magnitude 7.1. Centred 40km west of Christchurch. Epicentre near Charing Cross, 10km south-east of Darfield at a depth of 11km.
Widespread damage occurred, but no loss of life. Disruption to water, power and sewerage services.

There was definite ground movement out there


 It's basically a rural area at Darfield so there are not many people out that way and it wasn't that big a deal.

Of course if you happened to be one of those people it was a serious issue.


This road used to be straight.


In the distance in the above photo you can see some hills. Spreading out from them toward our view point is where Christchurch is.  This Quake caused some structural damage in Christchurch seriously weakening some of the older buildings, prepping it for what was to come just five months later.

TUESDAY 22 FEBRUARY 2011

12:51pm (NZ time), magnitude 6.3. Centred 10km south-east of Christchurch at a depth of 5km.
185 people were killed and there was major damage to Christchurch land, buildings and infrastructure.

Hammer Time!


What you are looking at here is the dust cloud created by collapsing buildings in the central business district of Christchurch.

It says above that the quake was centered 10k ( just over 6 miles) from Christchurch. That means Christchurches center.  This of course means the quake was centered within the city boundaries.

Although the above quote lists this quake as 6.3 other sources say 7.1. I'm inclined toward the latter figure.  The type of movement is important too. In this case it was sudden and sharp. Parts of Christchurch accelerated at 2.6 g ! It's a wonder really that anything was left standing and that the death toll was as small as it was.  A testament perhaps to modern building standards.

The  fate of many a home




I used to eye with some jealousy the neat homes perched among these cliffs. Here those cliffs are seen collapsing into the sea and the structures below.


In the hills there were avalanches of boulders.


The house of one of my friends was demolished by one of about this size flying through it.


There were many subsequent quakes or 'aftershocks', some of them quite large, up around the 5.3 range. This caused further damage and kept the people of Christchurch 'on their toes' (or increasingly traumatised).

All this was inspired by my sister posting a follow up vid on her facebook page. I thought some of you might be interested to see it and got carried away as usual.

Click on the link below to see the 2016 follow up video..
http://www.stuff.co.nz/the-press/christchurch-life/80947005/tracking-the-fate-of-christchurch-heritage

[oldbike54]

 Wow ! The rails on the track were like cooked spaghetti to the forces of Mother Nature 

 Dusty

[Moto]

Thanks for that reminder, and the photos I never saw at the time. How has the rebuilding gone?

Moto

[Muzz]

Rebuild going reasonably well Moto, although there are still some hiccups with some of the "anchor" projects. The resultant growth of satellite townships has thrown the traffic plans in to absolute chaos as the eastern suburbs got red zoned in many areas and many relocated to "safer" areas.

I actually wandered through the Christchurch Central square on Friday night going back to my vehicle, and there are still large gaps in some areas. Gave a rather surreal effect. The Cathedral in the square still sits forlorn surrounded by security fences, supported by steel bracing all over the place and open to the elements. Really sad.

The second shock that killed the 185 was unique evidently, in that it went up as well as sideways. When many of the buildings came down they missed their foundations by as much as over a foot. That, along with the massive acceleration caused huge damage. If you live in a double or triple brick construction and you get hit with an earthquake like that, beware. Most of the deaths were caused by falling unreinforced masonry.

[johnr]

Thanks for that reminder, and the photos I never saw at the time. How has the rebuilding gone?

Moto

Slowly IMHO. There have been some surprising 'goodnesses' come out of it, like the clever use of containers to provide premises for businesses.

For eg.


But if you watch the video you will see lots of open spaces.

We have the reluctance and lack of co-operation of insurance companies, the effects of the Earthquake and War Damage Commission having been run down by successive governments who never thought they would have to use it, and of course heavy handed interference by Government itself. These things combine to sticky up the works.   I'm not proud of the way this has gone, especially when you look at Napier which was totally destroyed by an earthquake in the 30s and totally rebuilt in two years!

[Muzz]

There is a photo montage on YouTube set the Springsteen's My city of Ruins.

There are two actually, the best one is about 8.1/2 minutes long and the song has been spliced to extend the time.

In the montage there a couple of young people shown, obviously distressed, waiting for news of their mother. (She did die in the quake). During her funeral, some asshats went and burgled the home. Some people really don't deserve to be allocated oxygen.

[johnr]

I would add to Muzz's comment that the integrity of brick construction is very much down to the quality of the mortar. 

I was brought up in an earthquake zone (which Christchurch is not considered to be)  in a triple brick house. (ie Brick construction not just cladding. The walls were 18" thick!)

After a particularly interesting earthquake I asked my (architect) father about this. His comments may be of interest.

He pointed out that first, an earthquake proof building is a contradiction in terms. There is simply no such thing. 
He said that "given good quality mortar, a brick wall will twist an amazing amount before it lets go". He added that by the time our house came down it wouldn't matter much what sort of building we were in.

That house was a high quality build that has stood in an earthquake zone since 1911 and has to my knowledge been subjected to many earthquakes. Without checking the records I know that includes earthquakes up to at least 7.4. (there may have been stronger ones in that time) It has yet to develop even the suggestion of a crack.

I would add that older wooden buildings can be at risk due to their fastenings  deteriorating. (and rot) When rusted nails break or pull out, during an earthquake bad things happen. All building types have their disadvantages.

In Christchurch the bricks that let go tended to be in the first instance the facades of older commercial buildings,  which of  course would have been built to strict price limits and cheap mortar. 

However in that type of earthquake absolutely nothing was either immune or safe.

In fact, the vast majority of the casualties were from the collapse of a modern building. The engineer hadn't (or couldn't) do his job. He had to do a runner to Australia to escape the consequences.  ( I would add that they should have used an architect instead.)

(edited this post to try and make things a little clearer)

[johnr]

There is a photo montage on YouTube set the Springsteen's My city of Ruins.

There are two actually, the best one is about 8.1/2 minutes long and the song has been spliced to extend the time.

In the montage there a couple of young people shown, obviously distressed, waiting for news of their mother. (She did die in the quake). During her funeral, some asshats went and burgled the home. Some people really don't deserve to be allocated oxygen.

Post a link will you Muzz.

[Sasquatch Jim]

  I just hate it when it does that!

[Arizona Wayne]

I would add to Muzz's comment that the integrity of brick construction is very much down to the quality of the mortar. 

I was brought up in an earthquake zone (which Christchurch is not considered to be)  in a triple brick house. (ie Brick construction not just cladding. The walls were 18" thick!)

After a particularly interesting earthquake I asked my (architect) father about this. His comments may be of interest.

He pointed out that first, an earthquake proof building is a contradiction in terms. There is simply no such thing. 
He said that "given good quality mortar, a brick wall will twist an amazing amount before it lets go". He added that by the time our house came down it wouldn't matter much what sort of building we were in.

Older wooden buildings are at risk due to their fastenings  deteriorating. This can be serious. Look it up. 

In Christchurch the bricks that let go tended to be in the first instance the facades of older commercial buildings,  which of  course would have been built to strict price limits. 

However in that type of earthquake absolutely nothing was either immune or safe.

In fact, the vast majority of the casualties were from the collapse of a modern building. The engineer hadn't (or couldn't) do his job. He had to do a runner to Australia to escape the consequences.  ( I would add that they should have used an architect instead.)

A brick building and an earthquake is oxymoron.  No way in hell are the bricks going to stay not impacted at that strong an earthquake.  I used to live in soCal and weathered the `71 earthquake there.  Luckily it hit when most everyone was still in bed.  For awhile I thought we were in a waterbed!  WTF ?!  Then after being in the US Navy on a Destroyer, it takes a real shaker now to get my attention. 

[rodekyll]

That's some pretty serious stuff.  Is this an earthquake-prone area?

[azguzzirep]

My wife and I were in both Napier and Christchurch last year. Napier was very cool. Looked like old Miami. We didn't get to go into Christchurch to look around though . Would have liked to.

When the Ridgecrest earthquake hit in SoCal the brick wall abutting my house bumped against the house for about a minute. My house was in Phoenix!

Tom

[johnr]

That's some pretty serious stuff.  Is this an earthquake-prone area?

Definitely not RK. In fact it was generally considered to be an earthquake free zone. (well, in so far as that is a reality on the edge of the Pacific Rim)

In some respects that may have contributed to the damage. In an known earthquake zone many of the older buildings would have been demolished or strengthened well before this event.

Even so, it was a 'high damage' form of earth movement as a result of which a lot of damage is inevitable.

The first of the two quakes mentioned above shocked everybody as no one knew that a fault was there. Perhaps in fact it is a new one?

Despite it not being in an earthquake prone area, when I lived in Christchurch I, who came from a quake prone area,  used to worry about this. 

Apart from the nearby Port Hills which are volcanic, the ground is all alluvial.  Most of Christchurch  is also near to and sometimes below sea level.   I could just imagine that if you shook it right, like a gold pan, it would all turn liquid.   There was a lot of liquefaction too but not as bad as I imagined it might be.

This brings another point to the fore. The fault that moved in 2011 extends past an old volcano (Lyttelton Habour) and on out to sea.  Now I don't know if there is any real danger, it being a relatively old and dormant one, but cracking open a volcano does not seem to me to be desirable.

If that fault movement should occur  further out at sea  in the future, then Christchurch can expect to be instantly tsunamied without warning.

(improved this post too)

[johnr]

My wife and I were in both Napier and Christchurch last year. Napier was very cool. Looked like old Miami. We didn't get to go into Christchurch to look around though . Would have liked to.

Tom

Yes Napier was demolished (by it's quake) and rebuilt when 'Art Deco' was the thing, so it was rebuilt in that style. 

[Stevex]

My daughter is living near Lake Taupo atm and is moving to Hamilton in September.
We're coming down from the UK to visit her at Christmas; unfortunately not on bikes, that'll have to wait for another time.
Looking forward to it.

[lucydad]

John,

Sobering indeed.  I lived by Earthquake Park in Anchorage, AK for about 3 years.  Right on the edge.  The Park shows the major slumps that destroyed the neighborhood.  My backyard had small pre-slump scars, it was primed to go.  Fortunately the big one in SE Alaska killed few people.  We had a 6.1 while I lived there, that was plenty for me.

Your pictures show clear evidence of a shallow, strike-slip style of faulting, at least partial.  Lateral tears in the rock really, really throw out some huge P and S waves, hence the extreme damage.  The Pacific "ring of fire" is well named.  Eventually our USA west coast and Pacific NW are going to endure some enormous quakes.  Los Angeles in particular will be ugly I think.  The San Andreas is a right-lateral slip system between two major plates.  When it releases stress, the results at often catastrophic.

Blessings to all in Kiwi-land.

[johnr]

 

My daughter is living near Lake Taupo atm and is moving to Hamilton in September.
We're coming down from the UK to visit her at Christmas; unfortunately not on bikes, that'll have to wait for another time.
Looking forward to it.

In keeping with the general subject of this thread Taupo is an interesting place. Once upon a time Taupo was a mountain. Then it blew up! (about 25000 years ago I believe)
I'm reliably informed that when that happened it made a bang that could be heard all over the planet and shot a column of lava 60km (or was it miles?) straight up. It came down again, as such things are want to do, and covered 3/4 of the North Island with lava in 20 minutes.  That's faster than the water would flow over it if you suddenly sank the land.
Now Taupo is our largest lake. (At least across. Not in depth or shoreline and I'm not sure about area)
It is one of the worlds super volcanoes though and is alive and kicking.

I hope you enjoy your trip here and get the time to have a bit of a look around.
The mantra is "3 days in the South for every 1 in the North.   

[rodekyll]

well, if it's not a recognized fault zone (to this point) I can see the brick houses.  But despite what your brick guy says, it's not a good building material for an earthquake zone, mortar notwithstanding (literally).  His logic doesn't wash.  He compares brick to old, clapped out stick houses and says it's no worse.  What he should be doing is comparing it to the conditions it needs to withstand and declare it better.  He can't do that.

I've got a dollar that says he wouldn't live in a brick house in Christchurch, and a nickel that says there are no genuine brick houses in Alaska.  In fact, an actual brick is almost impossible to find here since the tall ships stopped using them for ballast, and prohibitively expensive (several dollars each) -- you couldn't afford to build with it.

That said I have a brick pedestal for my smokehouse in the back yard.  We get little rattles here regularly that shake the bricks out of position.  I've built it with those 3-hole bricks and without mortar.  I've pinned the bricks through the holes with rebar.  Every few weeks all the bricks have shifted and I have to go around the structure with a rubber mallet knocking them back into place.  If it wasn't for the rebar the pedestal would disassemble itself several times a year.

The same stresses are happening to brick anywhere there is ground motion.  A person would be ->stupid<- to build in such an area with brick -- if the building code allowed it, which it probably doesn't.

[Arizona Wayne]

The reality is our so called 'experts' know diddly squat about when/where future earthquakes or volcanic eruptions are going to happen.   When Mt. St. Helens blew up the experts were all wrong about how long it was going to have plant growth grow in the wiped out areas again.  They knew no more than us pedestrians.   All they knew is what they and us observed together as the volcano went thru it's cycles.   OK, they knew it might blow up, but that's just because it gave warnings of that.

[johnr]

well, if it's not a recognized fault zone (to this point) I can see the brick houses.  But despite what your brick guy says, it's not a good building material for an earthquake zone, mortar notwithstanding (literally).  His logic doesn't wash.  He compares brick to old, clapped out stick houses and says it's no worse.  What he should be doing is comparing it to the conditions it needs to withstand and declare it better.  He can't do that.

Probably my limited language skills at play here, but that isn't what was being said.
(and he wasn't a 'brick guy'. Just an expert in buildings)

[rodekyll]

nevermind, then.  I probably misread it.   

[Muzz]

Link to the earthquake montage on Youtube; Bruce Springsteen, My City of ruins

https://www.youtube.com/watch?v=vLMiZxqT63U

When I watch it, it still brings back memories. I was on crutches after tearing the RH hammie off the pelvis. I can remember going down and then absolute pain as any healing that had happened unhappened. Stuff crashing down behind me. Not nice.

The teens I mentioned in the earlier post are at about the three minute mark. Seeing them again made me angry at the b*****d that robbed them while they were burying their mother.

[johnr]

Thanks Muzz, and thanks Bruce.  I found that tribute quite moving.

[steamdriven NZ]

For most of us the initial ones were bad, no doubt. But the 10,000-odd aftershocks (which still happen every couple of months ) were worse.
Everyone had their own personal go/ no-go gauge as in you'd look up when one came, gauge whether you were going to leg it outside or not (usually not, but.....) and then you'd bet coffees on how would get the closest guess to how big it was.
I actually did OK during the aftershocks, seemed to ride them out pretty well. But now its all slowed down (note I never said stopped!) the seem to affect me worse than I thought they would.

Oh well, like they say "prepare for the worst, hope for the best."

[Muzz]

But now its all slowed down (note I never said stopped!) the seem to affect me worse than I thought they would.

Oh well, like they say "prepare for the worst, hope for the best."

You and me both on that one Kev.

I think it is because the early ones started small and grew, these ones start big and taper off. However, my brain still expects them to keep building, which I find unsettling.