Earthquakes in New Zealand may have had a devastating effect on the Canterbury region in 2010 and 2011 but they have led to a new era of geotechnical data sharing.
When the first earthquake struck Canterbury in New Zealand September 2010 there was shock at the scale of the damage to land – largely liquefaction-related – and the geotechnical challenge of recovery soon became apparent. To aid the work, the Canterbury Earthquake Recovery Authority (CERA) worked with New Zealand’s Earthquake Commission (EQC) to establish the Canterbury Geotechnical Database to bring available geotechnical data together in one system.
Seven years on the spirit of collaboration born out of a crisis has led to setting up of a national database that is benefitting the whole of the country and a number of different professions. While forming the system was not plain sailing, the industry is already seeing the benefits and other nations are now beginning to emulate the New Zealand Geotechnical Database (NGZD) model.
The benefits of NGZD are not just felt in New Zealand – the system now has 4,500 users spread around the world. Users vary, with engineers making up the majority, but the system is also used by central and local government, academia, insurers, architects and property owners too.
“The NZGD project was ‘launched’ by the Ministry of Business, Innovation and Employment in 2015 under the guidance of its then chief engineer Mike Stannard with the financial support of EQC,” says EQC senior advisor John Scott. “Although this in reality was finding a new owner and nationalising an existing database previously restricted to Canterbury data.
“The technical, liability and data ownership barriers were, in hindsight, easy to overcome as the Canterbury model was driven by an urgent rebuild need and, with the disestablishment of CERA, there was a cross government recognition of need to find a new database owner at the very least to ensure the Canterbury rebuild continued at pace. The way the database technology – which was routine – had been set up meant that transitioning to a national database was technically easy.
“The more challenging bit was seeding the database with enough data to encourage use by consultants and clients outside of Canterbury who were not involved in the rebuild and therefore had not yet seen the advantages of sharing information,” explains Scott. “They saw the information they held as their competitive advantage which initially limited their enthusiasm to share data.”
This barrier was overcome when several territorial authorities and large utility organisations saw the benefit of holding and accessing their data via the NZGD. They started to progressively transferring historic information over to NZGD and placed a requirement on consultants working for them to upload any new information.
The database now holds, based on conservative estimates, about NZ$200M (£105M) worth of data and is growing, especially since several agencies shared the cost of a resource to “mine” old project files for data.
The full benefits of the database have yet to be quantified but they are expected to be wide-ranging. “The system is enabling more accurate liquefaction related insurance loss modelling estimates of Wellington during a future earthquake,” adds EQC general manager for resilience Hugh Cowan. “With a more detailed understanding of losses, re-insurance premiums are actually lowered as the uncertainty around the possible loss is reduced.
“The data also allows more accurate hazard maps, for example for liquefaction hazard, as there is better access to base data and less need to rely on basic geology maps as the Canterbury experience has revealed these are generally not granular enough to be useful for site assessment purposes.
“There is more efficient archiving and retrieval of data that also reduces risks associated with loss of corporate and institutional knowledge associated with serving individuals
“Lower site investigation costs are being achieved as consultants can access nearby data and therefore need less new information to confirm site models. This leads to more efficient foundation designs as the ground model is better understood and therefore less contingency needs to be built in and we have a better understanding of a sites issues and sub-surface model prior to selecting a site.
“International and New Zealand-based researchers are using the data set, which also includes the earthquake related land damage information, to update state-of-the art liquefaction prediction methodologies.
“While not the initial driver for the database, there is also a very strong sustainability component to the NZGD where data is created once and then reused many times.”
Home owner opportunity
Support for the NZGD was gained on the back of the benefits realised in Canterbury and these extend beyond the ground engineering industry and into banking and insurance too, adding advantages for home owners.
Land in the Canterbury green zone identified as TC3, which was the worst preforming land in the Canterbury earthquake sequence that was not that wasn’t “red zoned”. These areas were effectively excluded from redevelopment as gaining finance from banks and insurers was difficult to obtain.
In 2013, one of the larger New Zealand banks worked with its insurer to develop a new GIS-based borrowing review tool which relied heavily on geotechnical information from the CGD.
This GIS tool increased the bank’s knowledge and understanding of the geotechnical risks associated with a particular location, providing its frontline staff with the necessary information to be able to assess loan applications, without further investigation, for up to 90% of TC3 borrowers. The initiative, made largely possible by access to the CGD, has resulted in faster lending decisions and provides customers with certainty.
The CGD’s capacity to provide banks with a superior ability to evaluate the risk profile of a property has been called “a game changer”. The bank no longer needed to consider any lending distinction based on the one size fits all approach of technical categories of property. Similarly, access to geotechnical information has resulted in other banks taking into account, on a case-by-case basis, the insurability on a more granular rather than the area-wide technical category of properties.
Before the national database was set up the CGD was frequently accessed by engineering specialists and consultants commissioned by developers to undertake geotechnical investigations and assessments of land in the Canterbury region.
For example, in 2013 a developer was proposing to subdivide 20ha of land in Wigram, Christchurch and engaged a geotechnical consultant to coordinate a site investigation. The CGD was instrumental in providing the consultant with details on liquefaction observations and horizontal and vertical movement of the ground, which was key to supporting an application for resource consent.