[Moorf]

Took the dogs out this morning and, just outside our back gate were a couple of surveyors. Intrigued at their equipment, and what they were doing on our side of the road, I wandered over for a chat.

I wish I hadn't.

They were surveying.... not the road.. ohhh no.... a big quake fault-line that runs, literally, right past our back boundary - they were excited at some "interesting anomalies" that had occured underground right by our back gate :eek: :exit

[Sam B]

uh-oh!

[benandclare]

eek :exit

[jubjub]

:uhoh :exit

[Moorf]

Hmmm, there's a hill about 15km up the road from us in Springfield that is on/near the fault line - geologists have found it is rising at 6 inches a year! :uhoh I posted an article about it last year but it's gone now....

[ourquest]

Moorf, this doesn't add up. Surveyers don't measure or map fault lines, geologists do. And fault lines are often fault zones (ie not entirely confined) and if they described it as an "earthquake fault line" then it might be the result of an earthquake, not the cause of one.

Did they volunteer any information about how they knew what was underground at your back gate?

Usually an active fault can cause earthquakes, but it seems highly unlikely that it would be a new discovery (ie suddenly make your house lie in an area of high risk). New Zealand has so much seismic activity that their will be entire departments monitoring seismographs and interpreting their results on a daily basis.

Unless there are seismic stations all over your garden (there aren't) no scientist would pinpoint underground "activity" to be below your back gate.

Maybe they were enjoying some kiwi humour?

[Moorf]

They were using a ground radar machine-thingy and those tripod thingys and a laptop. Don't ask! Sorry, I didn't mean literally under my back gate - it's rural land out the back and they were all over the place....

They could well have been geologists - they were both Scandanavian so not sure about the Kiwi joke - I just called them surveyors because of the equipment they were using and I pretended to know what they were on about by saying "Oh yes, I love Time Team" *blank looks*....

Not much I can do about it anyway!! Assume it's been there a while :D

[ourquest]

Your post about the hill appeared before my last response.

If it is moving constantly then it is no risk for earthquake. It is in active fault zones which are under huge tectonic stress without moving where the danger lies. The stress builds up, and when the forces of friction are no longer sufficient, the fault suddenly moves and releases immense energy, which you feel as an earthquake. Geologists cannot predict the occurrence of an earthquake precisely because there is no movement which precedes it. They can only predict which areas carry more risk, and advise construction to be able to withstand the earthquakes. No one has lost a life in NZ as a result of a quake since 1964 (I think), although the risk does exist.

Unless you hear otherwise, assume you are relatively safe. Surveyors might know how to measure position, but neither you nor them have the knowledge to understand the mechanism or risk associated with geological fault zones.:)

[ourquest]

OK so they might have been geologists. Points still apply.

This is the problem with having an online discussion!

[Moorf]

It could also be part of the big geo-planning that is being done across our area of Canterbury due to the proposal to dam up a huge lake locally (Canterbury Water's great "irrigate the plains" idea. The plans have been opposed as the dam supposedly sits on a fault line, too.

I'll have to go and interrogate them tomorrow!

Well, they do say NZ rocks! :D

[ourquest]

, but neither you nor them have the knowledge to understand the mechanism or risk associated with geological fault zones.:)

And I should add that my own knowledge is a bit rusty!

[Moorf]

Rusty or not it was very interesting, ourquest, thanks! :nice1 I especially didn't know about how the hill rising was a good thing... might go climb it now! :D

[ourquest]

The plans have been opposed as the dam supposedly sits on a fault line, too.

:D

This is probably good news. The idea would never even have found an audience if the dam would locate on a significant or risky fault. The effect of the added stress imposed by the dam on the surface of the ground is difficult to quantify, and the added groundwater can effectively lubricate the fault line causing increased activity.
And if the integrity of the dam (the structure which retains the water in the reservoir) is ever compromised by ground movements the risk of downstream flooding might be significant. So studies will always be exhaustive.

So at worst the above is the case and the chaps are out in the field to try and assess for the dam. Doesn't mean it's a risk for you, then, they're just playing safe.

[Derv]

A Kiwi friend of ours said to us before we finally decided to emigrate "if you are worried about earthquakes, faultlines or volcanoes, don't move to NZ".

I think it's very exciting to live in a geologically interesting part of the world - though we did reject the option of buying a plot of land which was actually crossed by the Alpine Fault. It would have been fun living there but house insurance would have been impossible. :)

The only part of NZ which we have found to be geologically disappointing is the Rotorua area - the geothermal features there are far less impressive than Iceland.

Best wishes

Derv

[ourquest]

might go climb it now! :D

With respect to your enthusiasm, perhaps you should also wait at least until tomorrow.
:)

[Moorf]

With respect to your enthusiasm, perhaps you should also wait at least until tomorrow.

You're right - it's raining :D


A Kiwi friend of ours said to us before we finally decided to emigrate "if you are worried about earthquakes, faultlines or volcanoes, don't move to NZ".

So true! I love the fact that we're living in quake country - although I've only felt one biggie and a couple of littlies... not sure I want to wish for a big one :o but secretly I do! :confused: Perhaps I should visit Te Papa in Feb and experience the quake room (is it still there?).

I'm a bit vague on this, but isn't there quake/liquifaction insurance built in to mortgages/buildings insurance or whatever in NZ? I remember something about it when we purchased..... anyone?

[ourquest]

not sure I want to wish for a big one :o but secretly I do! :confused: Perhaps I should visit Te Papa in Feb and experience the quake room (is it still there?).


Both my brother and I originally qualified as geologists. I have never experienced anything other than minor tremors, but my brother, having lived in Chile for many years, has had his fair share. He used to enjoy them, and they used to have fun trying to guess the magnitude (hmmm, feels like a 6.2, etc).
Then they had an 8.6 (I think), and ever since he fears them. So although I secretly hope to experience a big one myself perhaps both you and I should listen to his wisdom and realise that it can be a very unpleasant and long-term anxiety producing experience. But he did survive it, despite watching his book shelves throw their contents to the floor for about a minute and a half. I guess it makes him more inclined to earthquake proof his home, although now living in Adelaide this is not at all necessary for him. But maybe you need to think a bit about your own heavy stuff balancing on little shelves and the top of your fridge.

The room at Te Papa is interesting, but I wouldn't think entirely convincing. It doesn't shake for very long at a time and it is relatively easy to stand in it, not apparently so in a significant quake. There is a smaller version at the Volcanic Activity Centre near Taupo, but both of these as well as the storm room at your own Christchurch Antarctic centre do not really demonstrate the huge power of real environmental events.

Don't forget to take your spade to the hill so you can remove the top 6 inches...this should really confuse the scientists!

[Derv]

I'm sure you are right about normal NZ house insurance. But, the problem was that the only available building site on the large plot of rural hillside land was actually crossed by the line of the Alpine Fault, not just near it. We were told that a building on, or within 10 metres of, an active fault line, as opposed to just being close to it, would (a) be unlikely to get insurance and (b) if it did, we would have to design in so many strengthening features that the budget would be too much for us to afford.

As it was, we decided that we didn't like the village (sorry - township) nearest to the plot of land so we didn't pursue the idea much further. Maybe we could have found a solution to the insurance issue if we had fallen in love with the whole area and decided that was the place for us.



Best wishes

Derv

[Moorf]

Don't forget to take your spade to the hill so you can remove the top 6 inches...this should really confuse the scientists!

:D

I sooo went the wrong direction in life - I so wanted to be an archaeologist or geologist :(

[Moorf]

I'm sure you are right about normal NZ house insurance. But, the problem was that the only available building site on the large plot of rural hillside land was actually crossed by the line of the Alpine Fault, not just near it. We were told that a building on, or within 10 metres of, an active fault line, as opposed to just being close to it, would (a) be unlikely to get insurance and (b) if it did, we would have to design in so many strengthening features that the budget would be too much for us to afford.

Ahh, that's interesting. Did the people who sold you the land tell you this or did you have to find out for yourselves? I know in Chch they appear to factor in liquefaction into most LIMs (or is it the survey, can't remember) but never fault lines. I assume that there are records somewhere that are referenced when a plot of land is sold? As my parents are looking for land it would be interesting to know whether they'd need to check that before building... :nice1

[Tanya]

Perhaps I should visit Te Papa in Feb and experience the quake room (is it still there?).


Yes it is - we went there on friday!!

Tanya

[Familyofmonkeys]

Perhaps I should visit Te Papa in Feb and experience the quake room (is it still there?).



yep :nice1

[Moorf]

Excellent!

Does it go continually throughout the day or just at certain times?




Here's a good follow-on thread from a while back on quakes and tsunamis....

http://www.emigratenz.org/forum/showthread.php?t=9684&highlight=inches

[Familyofmonkeys]

Excellent!

Does it go continually throughout the day or just at certain times?




Here's a good follow-on thread from a while back on quakes and tsunamis....

http://www.emigratenz.org/forum/showthread.php?t=9684&highlight=inches

It goes every 8 minutes.

[Familyofmonkeys]

:D

I sooo went the wrong direction in life - I so wanted to be an archaeologist or geologist :(

I'm a geographer personally......not sure exactly what that is though :o Did geology, earth science, environmental science, geophysics, gepochemistry etc. for most of my time at Uni....I love stomping around outdoors in my wellies :)


BTW....faultlines are not on LIM..only risk category for area. But, we found plenty of geological reports on the area before we decided to buy (although they are a bit tedious to read)...will have a look for some links later!

[Derv]

Ahh, that's interesting. Did the people who sold you the land tell you this or did you have to find out for yourselves? I know in Chch they appear to factor in liquefaction into most LIMs (or is it the survey, can't remember) but never fault lines. I assume that there are records somewhere that are referenced when a plot of land is sold? As my parents are looking for land it would be interesting to know whether they'd need to check that before building... :nice1


It was a while ago but as I remember it, we knew the fault line crossed the plot of land (it was several hectares) and was close to the build site; the local Council planning dept gave us lots of helpful information and many more details on the phone; and they suggested that there might be insurance problems within 10 metres of the fault line so I spoke to the local AMI office who confirmed it. If we decided to go further with the land purchase our next step would have been to pay for a proper geological survey.

I hope this helps.

[Moorf]

Cheers Derv - very helpful. :nice1

[aberdian]

There you go, from the New Zealand Active Faults Database http://maps.gns.cri.nz/website/af/ Looks like big active fault is the one going through Porters Pass towards Mt Thomas. NZ is an active geological area on a plate boundary - there's bound to be a few shoogles from time to time :) The red lines are the faults btw, before I assume that everyone knows what they're looking at! I was a geologist once, now I just pretend......

1020

[Moorf]

I can see the red line going through Springfield - that'll be the rising hill !!

Nothing marked near us though.. whew! Mind you, I'm still going out to interrogate the guys tomorrow :D

Thanks for that! :nice1

[IanW99]

I can see the red line going through Springfield - that'll be the rising hill !!

Nothing marked near us though.. whew! Mind you, I'm still going out to interrogate the guys tomorrow :D

Thanks for that! :nice1

Have you checked the GIS data from your local council website, normally you can zoom in and it will show you small faults that you won't see on the larger maps. Also shows lot's of other good stuff that you might find interesting?

Ian

[Moorf]

No, I haven't Ian, but guess what I'm doing right now... :)

[aberdian]

Have you checked the GIS data from your local council website, normally you can zoom in and it will show you small faults that you won't see on the larger maps. Also shows lot's of other good stuff that you might find interesting?

Ian
Good point, bear in mind that the red lines are only the active faults

The Other Ian

[Moorf]

I've just been out having a friendly natter with the guys outside (turns out they are geologists from Canterbury Uni).

I went out because a) I'm incredibly nosey and b) because I've had huge vibrations crashing through the house since midday.... almost like someone was pile-driving in the garden...

Anyway - turns out they are mapping fault lines - those associated with the active fault lines already mapped. The project is in conjunction with a Uni in Switzerland.

They have been setting off charges in the ground and have today laid a long line of them and they are set off every 10 mins or so - very loud and disconcerting. Apparently a note was sent to all houses in the area but we didn't get one. :roll

So, that clears up that little mystery... :)

[benandclare]

I've just been out having a friendly natter with the guys outside (turns out they are geologists from Canterbury Uni).

I went out because a) I'm incredibly nosey and b) because I've had huge vibrations crashing through the house since midday.... almost like someone was pile-driving in the garden...

Anyway - turns out they are mapping fault lines - those associated with the active fault lines already mapped. The project is in conjunction with a Uni in Switzerland.

They have been setting off charges in the ground and have today laid a long line of them and they are set off every 10 mins or so - very loud and disconcerting. Apparently a note was sent to all houses in the area but we didn't get one. :roll

So, that clears up that little mystery... :)

So the earth really has been moving for you :laugh :laugh

[jubjub]

Dunno if anyone has already mentioned it, but there is also an earthquake room at the Auckland museum in the Domain... its really cool (well, by cool, I mean well made!)

[Familyofmonkeys]

I've just been out having a friendly natter with the guys outside (turns out they are geologists from Canterbury Uni).

I went out because a) I'm incredibly nosey and b) because I've had huge vibrations crashing through the house since midday.... almost like someone was pile-driving in the garden...

Anyway - turns out they are mapping fault lines - those associated with the active fault lines already mapped. The project is in conjunction with a Uni in Switzerland.

They have been setting off charges in the ground and have today laid a long line of them and they are set off every 10 mins or so - very loud and disconcerting. Apparently a note was sent to all houses in the area but we didn't get one. :roll

So, that clears up that little mystery... :)

Am very jealous.....would love to have such a cool job :)

[Moorf]

Interesting reading.... http://www.orc.govt.nz/portal.asp?categoryid=1170

[Familyofmonkeys]

Interesting reading.... http://www.orc.govt.nz/portal.asp?categoryid=1170

Not planning on selling up now you have read it then?

[aberdian]

Am very jealous.....would love to have such a cool job :)
It's only cool when the weathers nice, when you've got rain dripping down your neck and numb hands the romance wears off quickly! :) And the oil industry is very short of people to work seismic crews if yer serious. Go and work in the desert making big bangs for 6 weeks, then back home for 4 - I always loved the pictures of seismic shoots as a student, but the reality is quite different.......

[Familyofmonkeys]

It's only cool when the weathers nice, when you've got rain dripping down your neck and numb hands the romance wears off quickly! :) And the oil industry is very short of people to work seismic crews if yer serious. Go and work in the desert making big bangs for 6 weeks, then back home for 4 - I always loved the pictures of seismic shoots as a student, but the reality is quite different.......

Unfortunately I can only wish.....reality is 3 small children!
I'd forgotten about the cold hands bit though....bought some nice thinsulate gloves for a pyrenees fieldtrip as a student....and then there was a heatwave so I put them somewhere safe 'just in case'.....haven't got a clue where they are now :roll

Got a few Uni friends in the oil industry...but they are all single!