Seismic risk standard for Canterbury not updated. Ministers deny awareness.

To whom it may concern:

This is to notify aspects of fundamental mismanagement on the part of the recovery authorities in Christchurch.

The seriousness of this matter is such that it could lead to another disaster in the future in Christchurch.

It appears that the NZS1170.5 standard has been left unchanged after the earthquakes. This is one of the most important documents for the rebuild, as it should include the increased seismic risk. This document defines the minimum strength for foundations and ground bearing. While it may be lawful to leave this standard as is, it is unethical to allow building on unsuitable land with foundations that are much too weak. This is potentially a pre-designed man-made future disaster for Christchurch.


70 Recommendations from the Royal Commission have been accepted by the government as at Sept 2012. But they have not been implemented.




The standard remains unchanged.


This standard is referred to in the Geotechnical Engineering Practice – Module 1 – Guideline for the identification, assessment and mitigation of liquefaction hazards. Geotechnical engineers are encouraged to follow this outdated load-bearing standard.



While the MBIE guides include SLS and ULS references, they are only guidelines that are not enforceable. NZS1170.5 is the applicable standard and it remains incorrect but enforceable.

According to LAW, the calculation references for ground shaking are SLS 0.06 g and ULS 0.25 g.

According to GNS Science and the Royal Commission, these should be significantly higher.

MBIE gives one reference for SLS of 0.13 while other SLS references are still to be announced.


MBIE published the following document in February this year.


  • Structural performance standards and practices: incorporating learning from the Canterbury earthquakes into the Building Code (specifically clause B1 Structure, and its supporting documents, particularly NZS1170.5 and NZS3101) and engineering design practices, to enhance and provide confidence in the structural performance of future buildings in New Zealand

These are fundamental documents that have been left as they were before the earthquakes. Leaving the update of these documents so late could be construed as wilful negligence on the part of the government.

At the Press debate on 4 September, John Key made the statement that 90% of claims had been settled. If the calculations for the settlement of these claims were based on NZS1170.5, ground bearing and foundations are likely to be well below requirements. This is a very serious issue that could potentially have dire consequences for Christchurch.

At a public meeting on Saturday, I specifically asked the Minister for the Earthquake Recovery, Gerry Brownlee, about the NZS1170.5 standard and why it had not been updated.

He replied that “all standards have been updated”. (Recording is available).

I asked Standards New Zealand about NZS1170 last week, and they confirmed that this standard has not been updated since the earthquakes.

This explains some of the highly dubious practices that are currently being witnessed in Christchurch.

Considering the amount of structural work that is allowed to take place in Christchurch as exempted from a building consent and therefore inspections. I regard this situation as a high probability of misuse of the current incorrect standards.

MBIE has identified this ambiguity as follows.

“Voluntary guidance could remedy these problems to some extent; however, leaving the supporting documents unchanged would see a conflict between them and the guidance. This would reduce the clarity of what is required for Building Code compliance.

Furthermore, the purpose behind setting appropriate seismic risk hazard requirements is to protect lives and property. Guidance is not normally used to achieve these critical objectives.

The option of publishing guidance would therefore not resolve the identified problems.”


Insurance claims are likely to be settled by legal definition if that is more affordable than using guides.


I would ask that this matter be given urgent priority and that standards be corrected to reflect the current situation here in Christchurch.


Hon Nick Smith, Minister for Building and Construction has denied any awareness or communications with GNS on this issue.
Attached see a letter in response to an OIA request in this regard.

Royal Commission, recommendations and MBIE

The Royal Commission considers that there must be greater focus on geotechnical investigations to reduce the risk of unsatisfactory foundation performance. 

This is my letter to MBIE as I am concerned about these issues.

I have been looking at the Recommendations by the Royal Commission.
One of them is the following.
“Ground-improvement techniques used as part of the foundation system for a multistory building should have a proven performance in earthquake case studies.”

I live on a highly liquefiable land and we have 38m down to gravel. Land measures at 10.7m, highest tide in the area is supposedly at 11.2m
ULS subsidence is measured to be 340-400mm down to at least 20m depth. Lateral spreading 70-200cm.

Are you aware of any ground improvements with a proven performance in earthquake studies that would solve this problem?
Have any tests been made? Are there any solutions?

Then in general for TC3 ground improvements in the eastern suburbs.
In general the depth down to gravel is 30-40m.
Liquefaction induced settlement is down to at least 20m.
Any gravel platform or ribraft solutions on this land is likely to increase the settlement based on houses that have sunk into the ground in these areas.

The geotech reports I have seen so far are not according to any acceptable standard.
Typically assume drained soil, Exclude Liquefaction probability, exclude lateral spreading, assume no building on site, stated preliminary, Exclude the Z factor (seismic risk)
Commonly only calculate settlement down to 10 meters when it is known that subsidence reaches far greater depth.
Designers and engineers are excluded from all liability in the current building act. The only thing that is monitoring them is their own code of conduct.
I think it would be fair to say that these practices are not acceptable by society.
What is MBIE opinion of these practices?
What can be done to stop this?

What ground improvement solutions are proposed for these situations and how have they been tested?
The seismic risk in this area is extreme. Two active fault lines are under these suburbs and we have had a downward tectonic movement here.

I look forward to your response.

Update to come.