Webinars on Geotechnical Engineering Practice Modules

The revised Earthquake Geotechnical Engineering Practice modules (MBIE/ NZGS, 2021) have been issued under section 175 guidance of the Building Act (2004) and summarise current best practice in earthquake geotechnical engineering with a focus on New Zealand conditions, regulatory framework, and practice. Module 1 provides an overview of the module series and seismic hazard values for geotechnical design. Version 1 of Module 1 includes significant interim changes to the PGA and Earthquake Magnitude values for geotechnical design in some areas of New Zealand, while the National Seismic Hazard Model is under review.   Since the issue of the revised Modules, NZGS received several questions and comments, especially related to Version 1 of Module 1. Therefore, NZGS and the Module 1 authors will run a live webinar on Module 1, Version 1 on 7 July 2022 to assist with its application.  The webinar will include:
  • Overview of the Module by Prof. Misko Cubrinovski, University of Canterbury.
  • Overview of how the NZSEE, SESOC and NZGS advisory “Designing for Uncertainty – Interim Seismic Hazard Guidance” expected to be issued in June 2022, relates to Module 1 Version 1 by Stuart Palmer, Tonkin & Taylor Ltd.
  • Live Q&A session with input from NZGS members to lead authors.
Webinar time will follow…….

Geotechnical Investigations Using QGIS Software

Register free HERE

Geotechnical practitioners typically use a variety of software tools during investigations, including Geographical Information Systems (GIS). While the value that GIS brings to the investigation is generally accepted, many practitioners do not know how to use this technology themselves. The fully subscribed GIS for Geotechs courses run by myself over the last 4 years, proves there is strong interest amongst our community in Australia and NZ to improve this situation. The GIS course I run uses an open-source product called QGIS (or Quantum GIS), that has an advantage for the registrant of not needing to purchase a license and which can be installed on private (or corporate) computers, running natively on 3 major operating systems. QGIS has become very popular world-wide for a variety of applications, has excellent online resources and the pace of development is staggering! In the last few years, I have increasingly used QGIS for my routine work. The purpose of this presentation is to demonstrate workflows I developed to solve particular problems using QGIS. Besides the use of GIS software, these workflows also include other tools such as spreadsheets, databases, drillhole software, structure from motion software, digital stereoscopes, etc. For those wishing to improve their generic GIS skills or just spectators, I am hoping my webinar will demonstrate what is possible with these tools. For those already expert in GIS (regardless of what software solution you use), I am hoping the examples will be of interest, as every project poses a unique set of challenges to overcome, and there can be many ways to solve these. The examples I present will be based around three recent projects I have been heavily involved in:

  • regional landslide susceptibility mapping for planning applications
  • linear risk-assessment along a tourist railway
  • site specific investigation and remediation of an active landslide

Key aspects under discussion will include;

  • the importance of thematic-based data models and authority tables
  • using symbology compatible with local standards (e.g. AS1726:2017 Geotechnical Site Investigations)
  • cartographic tools for detailed map presentation
  • accessing global data through web services
  • georeferencing plans and orthorectification of historic aerial photographs to understand site history
  • working with digital terrain models to understand and model landscapes
  • raster modelling using published (open-source) algorithms and bespoke python scripts to develop geotechnical models

About the Presenter Colin Mazengarb completed a MSc in geology from the University of Auckland and spent the following 20 years working as a regional geologist with the NZ Geological Survey and successor organisations. He migrated to Tasmania in 2003 to work as an engineering-geologist with the Tasmanian State Government, primarily undertaking landslide zoning. He was an early adopter of desktop GIS and the skills he has developed has been of great advantage throughout his career. Colin and his partner Janet have 3 children and one grandchild, all living in Hobart.

Webinar: Unsaturated Soil Mechanincs for Slope Failures

Join the New Zealand Geotechnical Group for a presentation on unsaturated soil mechanics for rainfall-induced slope failures, presented by Prof. Harianto Rhahardjo (Nanyang Technological University, Singapore).

Free to Register HERE Rainfall-induced slope failures are commonly observed in residual soils during rainy seasons. Numerous residual soil slopes are generally unsaturated because of the commonly deep groundwater table. Therefore, it is important to develop a slope susceptibility map to identify areas that are susceptible to slope failures during rainfall. Incorporating unsaturated soil properties in the development of slope susceptibility map will result in more realistic and sustainable assessments of regional stability of slopes under rainfall. The development of such a susceptibility map using the Transient rainfall infiltration and grid-based regional slope stability (TRIGRS) model and Scoops3D for three-dimensional slope stability assessment will be discussed at the presentation. Two-dimensional (2-D) seepage and slope stability analyses on the selected residual soil slopes with past failure history were carried out to evaluate the established slope susceptibility map. The minimum factors of safety from the numerical analyses of the investigated slopes were in good agreement with the minimum factors of safety obtained from the slope susceptibility map. In addition, several slope improvement methods using the principles of unsaturated soil mechanics such as Capillary Barrier System (CBS) and GeoBarrier System (GBS) will also be illustrated with some case studies. About the speaker: Professor Rahardjo is a registered Professional Engineer (PEng) in Saskatchewan, Canada and Singapore. He has served as a consultant on various projects for several engineering firms and government institutions in Southeast Asia, Hong Kong, China, Canada and Australia. He has conducted extensive research on unsaturated soil mechanics to solve geotechnical problems associated with tropical residual soils. His research focus has been on rainfall-induced landslides; one of the major natural disasters occurring in many parts of the world.  He has applied unsaturated soil mechanics principles to better understand the mechanisms of rainfall-induced slope failures especially in tropical residual soils. Professor Rahardjo is currently developing Advanced Moisture Sensing Technology for Urban Greenery and Monitoring of Slope Stability. Professor Rahardjo is the co-author of the first textbook on unsaturated soils “Soil Mechanics for Unsaturated Soils“, by D.G. Fredlund and H. Rahardjo, published by John Wiley in 1993, the second textbook “Unsaturated Soil Mechanics in Engineering Practice”, by D.G. Fredlund, H. Rahardjo and M.D. Fredlund, published by John Wiley in 2012 and over 400 technical publications.  He has also presented his research works in numerous keynote / invited lectures and short courses in various countries.

NZGS Webinar: Mine Subsidence: Cause, Effect, Mitigation

Presenter: Gennaro G. Marino, Ph.D., P.E., D.GE., F.ASCE (Marino Engineering Associates, Inc. Saint Louis, MO) LINK TO FOLLOW Abstract: This presentation covers key aspects of mine subsidence engineering, a subject that is not well understood, and embraces a number of engineering disciplines. It focuses on the causes of mine subsidence and how mine stability relates to the resulting ground movements. Different mining and geologic conditions determine the mode of failure of the mine. The mode of mine failure in turn affects the resulting subsidence movement. Prediction of subsidence and damage potential are also key aspects of subsidence engineering. Case histories will be presented which illustrate different ground movement and damage scenarios. This presentation will be presented in a manner that will be understandable to anyone that would be interested in learning more about mine subsidence.   Short Biography: Dr. Gennaro G. Marino received his Ph.D. in Civil Engineering in 1985, from the University of Illinois. His thesis topic was related to mine subsidence and structural response to subsidence over room and pillar mines. Dr. Marino presently has a P.E. license in 28 states. He is the recipient of several awards, including the Distinguished Alumnus Award from the Civil and Environmental Engineering Alumni Association of the University of Illinois, and the Central Illinois ASCE Civil Engineer of the Year. Working in the area of mine subsidence for over 40 years in various ore fields in the U.S., Dr. Marino has authored over 100 articles and publications on subsidence engineering topics and consulted on all aspects of subsidence engineering with government agencies, engineering and architectural firms and other stake holders.

Webinar: Lessons to be Learnt

Register HERE


Lessons to be Learnt | 1 – Abbotsford Landslip Disaster

Landslides in the urban environment remain common. Hundreds of houses are damaged every year. Over the Telethon weekend of 30 June to 1 July 1979 more than 100 houses were damaged by rainfall triggered landslides in Auckland. With the damaged houses dispersed over a wide geographic area there was very little media interest. The Abbotsford landslip a month later was much more dramatic and photogenic, and it captured the interest of not only the media, but politicians as well.

About the presenter:
Nick Rogers QSO, MSc (Hons), a geomorphologist and geotechnical specialist recently retired from Tonkin + Taylor, takes us back to August 1979 and explains the impact the Abbotsford Landslip disaster had on urban land stability assessments. Nick is a specialist in natural disaster assessment and management, and has attended most of the natural disasters in New Zealand from Abbotsford in 1979 to the floods in Westport in 2021. Nick was a Director of T+T for 20 years, and at the time of his retirement in January 2021 was a Technical Director.

Webinar: Experimental Investigation into Multiple Occurrence of Liquefaction

Link to registration HERE

Speaker: Professor Junichi Koseki


Multiple occurrence of sand liquefaction has been reported in the past case histories worldwide, including those on the 2010-2011 Christchurch Earthquakes in New Zealand and on the 2011 Off the Pacific Coast of Tohoku Earthquake in Japan. In order to reveal the multiple-liquefaction behavior, a series of 1-g shaking table tests on level ground and another series of cyclic stacked-ring shear tests on hollow cylindrical specimen with/without initial static shear are conducted. It is observed that, though overall densification is observed in the two series of tests, the response of sands during the current liquefaction stage is more predominantly affected by the liquefaction history in the immediate-past stage. In case of the cyclic stacked-ring shear tests with initial static shear, significant effect of anisotropy induced by the immediate-past liquefaction history is also observed.


Dr. Junichi Koseki is a professor at Department of Civil Engineering, the University of Tokyo (UTokyo), Japan. He obtained his Bachelor, Master and Doctoral degrees from UTokyo. During the period of 1987-1994, he worked as a researcher at Public Works Research Institute, Ministry of Construction, Japan. In 1994, he moved to UTokyo as an associate professor at the Institute of Industrial Science. After promotion to professor in 2003, he moved to his current position in 2014. His research fields include liquefaction and its countermeasures, deformation and strength properties of geomaterials, and seismic behavior of earth structures. He received the C.A. Hogentogler Award from Committee D-18 on Soil and Rock, ASTM in 2000 and 2004, and the Best Paper Award from the Japanese Geotechnical Society in 2007, 2009, 2010, 2012, 2016 and 2021. He was also the 2010-2011 Mercer Lecturer endorsed jointly by the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE) and the International Geosynthetics Society, and the 2019 Bishop Lecturer of ISSMGE.

Webinar: Geomechanical Characterisation of Grey Wacke

Join the New Zealand Geotechnical Society and Chris Massey to discuss Geomechanical characterisation of greywacke rock masses for dynamic slope-stability analysis, Wellington New Zealand.

Register HERE

Torlesse greywacke comprises about 19% of New Zealand’s rock mass at/near the surface. Wellington is New Zealand’s capital city and is underlain predominantly by closely jointed greywacke. The region is also seismically active, and the central city is dissected by the Wellington Fault, which could generate a magnitude M7+ earthquake, with an estimated return period of about 800 years. This research has been carried out as part of the multiyear, multidisciplinary Stability of Land In Dynamic Environments (SLIDE) research project, whose goal is to improve the resilience of New Zealand’s buildings and infrastructure through better knowledge of the behaviour of slopes and develop strategies for more robust remediation approaches. To investigate the seismic response of the greywacke slopes we drilled eight boreholes and used full waveform sonic, and optical and acoustic televiewer downhole survey tools to characterise the insitu rock masses. These results – coupled with field mapping and laboratory unconfined and tensile strength testing of cores containing small-scale, short persistence and closely spaced discontinuities – have been used to derive rock-mass strength properties for dynamic slope stability analyses. This paper will discuss the relationships, or not, between the different scales of observation and measurement and their impact on deriving rock mass geomechanical properties at the slope scale.

This is an updated version of Chris’ presentation at the 2021 NZGS Symposium in Dunedin.

Chris Massey is an engineering geologist with more than 23 years of consultancy and research experience in the investigation and analysis of complex geological and geotechnical data for landslide and slope stability including landslide monitoring, foundation design, underground/surface rock support and groundwater problems. He has applied these skills to geohazard and risk assessments, oil and gas pipelines, highway, railway, mining engineering and town planning projects in Africa, the Himalayas, Europe, South East and Central Asia and Australasia. Chris has a degree in geology from Leeds University, UK; a masters in Engineering Geology from Imperial College, London, UK; and a PhD in engineering geology from the University of Durham, UK. Dr Massey has published many peer-reviewed journal papers and has given lectures and workshops around the world.