The seismic design of Australian dams is described as being relatively young when compared with other countries, such as the US or Japan. As Quigley et al explain in recent research published in Environment Systems and Decisions, early dams built before the 1970s generally weren’t designed to consider seismic loading, primarily because Australia was perceived to be a tectonically stable region with lower seismic risks.
However, after one of Australia’s most significant seismic events – the Meckering earthquake in 1968 which measured 6.9 on the Richter scale – and following improved global understanding of seismic hazards, from the late twentieth century onwards seismic loading was included in new dam designs, becoming more formalised with the adoption of seismic hazard assessments.
Australian dams are predominantly concrete gravity, and earth fill embankment dams which are more common in rural areas and were constructed throughout the twentieth century. Many older dams have recently undergone structural upgrades to meet more stringent seismic design criteria.
Australian dams
In their study Quigley et al wanted to obtain estimates of ground surface rupture and ground motion hazards at standardised scales useful for general reference and regional comparisons of dams registered with the Australian National Committee on Large Dams.
Geospatial and statistical methods were used to investigate the exposure of dams to seismic hazard from 409 faults in the Geoscience Australia Neotectonic Features Database (NFD). They identified 216 NFD fault traces within 100km of 428 ANCOLD dams.
Allowing for geospatial measurement and mapping uncertainties, between 16 and 31 dams could be directly exposed to primary ground surface rupture hazard on NFD faults. Displacement modelling on these dam-proximal faults yielded displacements that exceed suggested tolerable limits for fault displacement through foundations.
The authors conclude that detailed fault studies will increase knowledge of many dam-proximal faults to better support dam hazard and risk analyses. Fault studies could include mapping of fault traces with LiDAR and other high-resolution geospatial datasets, paleoseismic trenching to establish rupture characteristics from past earthquakes, geological and geophysical studies to better characterise fault geometries and displacements, and Probabilistic Fault Displacement Hazard Assessment.
New Zealand
In comparison to Australia, New Zealand is situated at the convergence of tectonic plates and is a seismically active country which faces unique challenges, often in the form of frequent, large seismic events.
Built for Waimea Water by Fulton Hogan and Taylors Contracting, the 52m high concrete faced rockfill Waimea Community Dam is the first large dam to be constructed in New Zealand for 25 years, and the first publicly funded large dam to be constructed since the Clyde Dam was finished 30 years ago.
Located in the northwest part of New Zealand’s South Island, the project was completed in early 2024 with the primary purpose of providing irrigation and community water supply.
As the dam is sited on the boundary of the Australian and Pacific tectonic plates, it lies in a region of high seismicity with several regional active faults within 12km of the dam site in different directions. This meant that the project necessitated a geotechnical approach to ensure appropriate seismic performance and internal stability of the supporting embankment materials, including a comprehensive understanding of the movement of the various components of the embankment during an earthquake. While structural configuration of the upstream zone of the structure had to be able to resist earthquake effects, with an emphasis on ensuring dam safety during and after such an event.
Key elements of Waimea Community Dam’s seismic design include:
- An erosion-resistant and flexible rockfill embankment, allowing controlled movement during earthquakes. The overarching embankment design performance requirements were the accommodation of earthquake deformations and conveyance of post-earthquake leakage which would have reduced embankment stability to an unsafe level.
- A reinforced concrete facing slab with appropriate slab dimensions, joint details and reinforcing.
- Constructable pre-cast upstream crest wall elements.
- Flexible waterproofing elements connecting the facing slab to the crest walls, as well as between wall elements with appropriate capability for accommodating large movements, and post-seismic flooding.
Wave velocity parameter
Other research has recently shown how the shear wave velocity (Vs) parameter can be used as a useful tool for maximising hydropower station safety against earthquakes.
The Vs are a type of seismic wave that move perpendicular to the direction of the wave propagation. They are responsible for causing the most damage during earthquakes as they can create significant ground motion and lead to soil liquefaction and landslides.
In Frontiers in Environmental Science, Song et al explain how this parameter helps to determine the velocity at which shear waves travel through rock layers, which can indicate their stability and susceptibility to earthquakes. Rock layers with high Vs are more stable and less likely to experience significant shear rates during an earthquake. In contrast, rock layers with low Vs are more susceptible to damage and can experience significant shear rates during an earthquake.
Investigating the significance of the Vs parameter in evaluating the potential shear rate of rock layers surrounding hydropower stations, the authors show how it can be used to ensure their safety and efficiency in earthquake-prone regions.
Machine learning and seismic design
As Song et al discuss, machine learning (ML) holds immense promise in enabling proactive safety control by using advanced data analytics to monitor environmental conditions and detect potential safety hazards in real-time, ultimately detecting data patterns that human analysts might miss. Algorithms can learn to recognise subtle changes in seismic activity that might indicate an impending earthquake.
The authors say their research uses a novel approach using vertical seismic profile data, typically collected to assess subsurface formations in oil and gas wells, near various dam construction sites. This methodology aims to facilitate geotectonic assessment of the foundation formations of dams and hydropower stations, enabling researchers to gain valuable insights into potential risks and challenges associated with their construction and operation.
Additionally, the research introduces a new methodology of using Extreme Learning Machine (ELM) models to predict the Vs of rock layers in hydropower station foundations. The proposed approach uses ELM enabled Vs prediction to assess seismic hazards and design appropriate safety measures. By accurately predicting Vs, this method can assist engineers and policymakers in making informed decisions to mitigate potential risks associated with seismic activity.
Seismic activity is highly complex, and even with advanced data analytics tools, the authors say there are still many unknown factors that influence when and where an earthquake will strike. As such, current efforts are focused on improving our understanding of seismic phenomena and developing more sophisticated tools to detect and respond to earthquakes as they occur.
Bhutanese risks
Bhutan is among the most vulnerable countries to natural disasters and climate-related hazards, including earthquakes, droughts, and floods. With its economy highly reliant on the hydropower sector that faces such risks, last year the World Bank approved US$40 million in financing to help strengthen the country’s institutional and technical capacity to manage such increasing hazards.
This financing will help strengthen institutions to safeguard critical infrastructures, including new hydropower projects and buildings as well as strengthening early warning systems and financial resilience of communities.
The operation will support safeguarding the hydropower sector – the country’s economic backbone – from natural disaster and climate risks through measures such as mandating that all new hydropower projects adopt a catchment-wide approach to increase resilience for all stages of development. The Kingdom has already revised the Guidelines for Development of Hydropower Projects and the Dam Safety Guidelines for Hydropower ensuring integrated dam safety and geohazard management.
REFERENCES:
Exposure of Australian dams to seismic hazard from proximal faults by Mark Quigley, Tim Werner, Yuxiang Tang, Dan Clark, Jonathan Griffin, Haibin Yan. Enviroment Systems and Decisions (2025) 45:24.
Maximising hydropower station safety against earthquake through extreme learning machine enabled shear waves velocity prediction. Tao Song, Di Guan, Zhen Wang and Hamzeh Ghorban (2024), Front. Environ. Sci. 12:1414461.
Seismic Resilient Design of Waimea Community Dam by Brian Benson, David Cmeron-Ellis, Peter Amos. ICOLD Chengdou May 2025. Q.111- R.12. DOI: 10.1201/9781003642428-115
