This issue is yet another Special Edition with a very good reason. The International Association for Engineering Geology and the Environment was founded in 1964 and it is therefore celebrating 60 years this year. The New Zealand Geotechnical Society has close links with the IAEG and our New Zealand Representative, Ross Roberts has collated several pieces that are included in this edition of NZ Geomechanics News. With a lean towards more engineering geological subjects, we searched the archives for the first article focused on Engineering Geology, finding one from 1972, in only the fifth edition of NZ Geomechanics News. The editorial from that fifth edition suggested the article may raise some controversy but called for more content from engineering geologists to ensure this publication remained balanced between the engineering and geological sub-disciplines. It is pleasing to see that today as the society represents all geo-professionals, this magazine is also a balanced publication, except of course for this Special Edition which leans heavily towards the Engineering Geology end of the spectrum with just four, but four significant articles, plus many more society and conference reports, news summaries and member recognition. The latter part of 2024 has also seen the industry lose some of the house-hold names globally and locally, it is always sad when there are several obituaries in the magazine, but it is fitting to be able to celebrate the lives of these remarkable individuals who have contributed so much over the years.
The techniques available today with the use of ever-evolving technologies would have been no more than a dream 60 years ago. Our feature article this month presents a very comprehensive study of the quantitative life safety risk assessment of residents in Muriwai following Cyclone Gabrielle. Three-dimensional modelling of the terrain from LiDAR data, plus historic aerial photographs enabled the team to develop the landsliding history of the region, with cored borehole ground investigation effort put in to develop the ground model with as much confidence as possible. RAMMS and other 3D software has become “run-of-the-mill” these days compared with 60 years ago and consequently the team were able to develop a detailed and robust qualitative risk assessment.
The East Coast Bays Formation is well known to many and we have a paper discussing the unique properties of this material specific to slope stability of case study sites around Auckland, supported by detailed laboratory testing, and the authors present some very valuable data for anyone working with ECBF. The paper is the culmination of a Master’s research project, so often these allow far more detailed research than commercial projects and the authors have made full use of the available resources and scope.
Jumping to the South Island, the article in this edition analysing the effectiveness of helicopter sluicing as rockfall risk reduction following the Kaikoura earthquake may not seem all that futuristic, but through their analysis, the authors have increased our understanding of when and where to use it, improving efficiency and helping to inform more targeted approaches in the future.
Lastly, we have another slope stability focussed piece which supports the Slope Stability Guidance Unit 3, which as many will be aware, introduces the concept of the target factor of safety dependent on the uncertainty involved. The paper provides a detailed description of the methodology behind the concept that is only broadly described in the Guidelines.
As we draw to the end of another year where the industry has had its ups and downs, we wish you all a very Happy Christmas and hope you enjoy some relaxation with friends and family over the holidays, and fingers crossed the weather behaves too!
Camilla and Robert
