@theelephantintheroom #55: "These clay and silt layers are typically the residue of esturine and swamp/lake deposits, thus small and localised and not resulting in large scale resistance to vertical movement of fluids, such as water, from above. They only serve to 'muffle' not block the vertical movement of liquids and heat across the whole structure."

Are these your own words or are you cutting and pasting from a scientific publication? If the latter is the case then you should be making this clear with quotation marks and reference to the source document.

An interesting post on this weblog (http://www.oriontransfer.co.nz/blog/2011-03/why-are-we-having-earthquakes/index) from someone using the nickname "prognos"":

"... The theory is that the massive extraction of water from the aquifers has sufficiently changed the pressure balance within the underlying structures to trigger the series fo movements we have all experienced."

One can't help but notice the word for word similarity between much of the material in the comments posted by "prognos" and what's been posted in here by elephantintheroom/shjohnkey. The only difference is that prognos is saying that depletion of the Canterbury Aquifers is changing the "pressure balance" within underlying rocks rather than the temperature of the latter as is being suggested by elephantintheroom/shjohnkey.

So is depletion of the Canterbury Aquifer causing a change in temperature within underlying rocks or a change in "pressure ballance"???

One point I ommitted in post #54(in reply to Martins post #52, is in relation to the clay and silt layers mentioned in martins detail quote on the layers of sediment composing the sub aquifer layers of Canterbury. These clay and silt layers are typically the residue of esturine and swamp/lake deposits, thus small and localised and not resulting in large scale resistance to vertical movement of fluids, such as water, from above. They only serve to 'muffle' not block the vertical movement of liquids and heat across the whole structure.

Martin #49, you state- "The sedimentary sequence consists of permeable lithologies such as sandstones and finer grained sediments with enough interconnected fractures to be permeable. Note that there are also _less permeable_ lithologies such as silt and claystones that present a _barrier_ to vertical migration of fluids. Even within the Canterbury Aquifers there are peat beds and other clay/siltstones that restrict vertical migration of fluid between the individual permeable units that that make up the aquifer."

OK, Thank you. Shall I emphasis the 'enough interconnected fractures to be permeable'? Do you dispute that the Canterbury aquifer is considered to be largely a single body of water permeating the majority of Canterbury, with some minor semi isolated areas, such as that under Christchurch city?

The semi permeable nature of some of the layers,directly relates to their structural rigidity, perversely making them MORE subject to fracturing of seismic origin....fracturing likely to have occured over millions of years.

The naturally permeable layers such as gravel and sand are less affected by seismic activity, but are already permeable.

The semi permeable layers would explain the relative coolness of the aquifers being currently mined for irrigation water, while the deeper sections flow out to sea releasing heated water in known vents onshore and offshore, acting to cool the geothermally highly active layers below.

Thank you, for providing greater detail and depth to the theory Martin. BTW, you proclaim scientific training publicly, therefore to send some secret message to me via the Press is not consistent to a public forum.

All readers deserve the facts behind claims made in this forum, don't

Martin #49,50. I did thank you for your acknowledgement that the Canterbury geothermal gradient is high at 30 c /1000m(see my post at #37).

However I have not ASSERTED that the geothermal gradient has changed due to irrigation extraction...that, I have POSTULATED...(ie to put up for consideration, NOT to claim as fact, as in assert)

There is a crucial difference I hope you shall appreciate, being the trained scientist you profess to be...it is the same difference as between fact and theory...something fundamental you seem to regularly confuse.

Failing to grasp this distinction, does rather undermine any claims to scientific credibility, let alone allow a reasoned debate to progress beyond blind assertions!

Let us be very clear...this is a theory. I am not claiming it is proven fact, and never have. It is simply a theory, and shall remain that until proven wrong.

thelephantintheroom #48: " What is it about the theory that is wrong in logic or fact?"

Everything is wrong about your "theory". You propose that production from the Canterbury Aquifers has increased the geothermal gradient of the Canterbury Basin. You have yet to provide any evidence that the geothermal gradient has changed at all since the start of exploitation of the aquifers. Until you provide this data your "theory" will never be taken seriously.

"Who do you work for Martin? You have claimed publicly to be a geologist, but refuse to identify publicly who you are or who you work for."

I have responded to all these queries in previous posts from you. Before Christmas I offered to submit a letter from my employer along with certified copies of my qualifications to The Press who would then on forward them to you. I never heard back from you.

Now, instead of beating about the bush asking questions you've already asked and I've already answered how about providing us with some cold hard data to support your 'theory"?

martin#49,50. Your grasp of the nonmenclature of geology is wonderful, but all the technical detail you furnish does not in anyway reduce the validity of the theory described at post #7.

Intricate detail does not make a scientific dialogue Martin. A logical reasoned argument of the known facts the possible functioning of the systems forms a theory and a theory does not require all its expected outcomes to be firmly measured and recorded to be a valid theory. I welcome a reasoned, argument form any interested parties, to refute the basis of the theory, but none seem forthcoming.

You have not rebutted a single essential point of the theory proposed...only quibbled on irrelevant detail.

The theory stands, and it will either be ignored, or investigated with an open mind and scientific resource. Most of the scientists I have discussed it with agree it deserves study, but is unlikely to receive it under current political management.

@elephantintheroom #47: "Al#26 For the proof please see http://www.stuff.co.nz/the-press/news/christchurch-earthquake-2011/quake-science/5379813/Ask-an-Expert-where-does-liquefaction-come-from To quote from GNS scientist Russ Van Dissen in the above article- 'How hot is it down there? Rather warm. In this part of the South Island temperature increases with depth at about 30 to 35 degrees Celsius for every 1km, so at 10km to 11km the temperature would be about 300C to 380C (the pressure would be fairly intense as well).'"

Don't you read any of my posts???? I actually agreed with your quoted geothermal gradient figures for the Canterbury Basin. The gradient isn't in question...it's your assertion that over time production from the Canterbury aquifers has led to an increase in the geothermal gradient of the Canterbury Basin.

@elephantintheroom #39: "..at 3 km there are the shale layers you and your buddies want to frack, so not only does water penetrate the already fractured shale and bedrock,(from the aquifer above, heard of gravity Marty?(Newton?(apple?(3rd form science?(no?))))"

Your grasp on Geology is at best tenacious. The Canterbury Basin is infilled with layers of lithified sedimentary rocks and younger overlying unlithified sediments. The layering of the sediments is horizontal to subhorizontal. The sedimentary sequence consists of permeable lithologies such as sandstones and finer grained sediments with enough interconnected fractures to be permeable. Note that there are also _less permeable_ lithologies such as silt and claystones that present a _barrier_ to vertical migration of fluids. Even within the Canterbury Aquifers there are peat beds and other clay/siltstones that restrict vertical migration of fluid between the individual permeable units that that make up the aquifer.

Of course if you spent a bit of time on Google you'd know all this...but hey, why let the facts get in the way of a good conspiracy theory??

Martin #41, #42 You are making very minor inconsequential qualifications to my descriptions to try to undermine my main argument, to no avail. Your inability to undermine the basis of the theory is inconsistant with your apparent opposition to its validity, and only serves to call into question your scientific detachment and disinterested objectivity on this matter. What is it about the theory that is wrong in logic or fact? Is it just that your employers would rather not wish their employees to consider such things? Who do you work for Martin? You have claimed publicly to be a geologist, but refuse to identify publicly who you are or who you work for. My comment earlier about the boiling point of the hydrocarbons present in the layers (0.5-5km) below the depleted aquifer of Canterbury, was of course, rhetorical.