Using Historical InSAR Data for Tailings Dam Monitoring: Why the Past Matters

Tailings dam monitoring requires more than periodic inspections—it demands continuous, large-scale visibility of ground.

However, traditional monitoring methods often lack the continuity and spatial coverage needed to deliver a complete understanding of ground behaviour.

Historical datasets provide a continuous, high-resolution record of deformation, revealing trends that short-term monitoring cannot capture. Using satellite-based radar technology, InSAR (short for Interferometric Synthetic Aperture Radar) enables the precise detection of surface deformation, revealing trends and patterns that are often undetectable through conventional, short-term monitoring approaches.

As such, by leveraging historical datasets, engineers and asset managers can gain valuable insight into the evolution of deformation over time, allowing potential risks to be identified well before they escalate. This supports more informed decision-making and strengthens proactive risk management strategies.

In practice, this means monitoring deformation across entire tailings facilities, identifying zones of accelerating movement, understanding the drivers of instability (such as moisture or slope geometry), and flagging areas that require further investigation—before they become critical.

This article explores the value of historical InSAR data in tailings dam monitoring, and why understanding past ground behaviour is fundamental to achieving safer, more resilient mining operations.

The challenge of tailings dam monitoring

Tailings dam monitoring is fraught with complexities. Engineers often face limited visibility into ongoing conditions, and traditional methods can be costly and infrequent.

Data gaps increase uncertainty, and without continuous insight, identifying potential failures can become difficult. 

The stakes are high, as tailings dam failures can result in catastrophic consequences, as evidenced by major incidents such as the Brumadinho (2019) and Mariana (2015) disasters in Brazil, and the Mount Polley breach in Canada (2014).

Brumadinho dam disaster. The collapse of the dam released a mudflow that engulfed the mine's headquarters. Photo credit: Ibama from Brazil

In order to prevent such failures, monitoring today must align with evolving regulatory frameworks, particularly in light of the Global Industry Standard on Tailings Management (GISTM), introduced in 2020, following major failures. 

A key challenge lies in the limitations of traditional monitoring approaches. Manual inspections, geotechnical instruments, and intermittent surveys often fail to detect subtle, progressive changes over time. This creates a complex environment in which stakeholders must be reassured despite data that may be incomplete or fragmented—further compounded by the ongoing pressure to optimise costs without compromising safety.

What is InSAR and how does it work?

New technologies offer promising solutions and provide precise, long-term insights that can significantly improve monitoring accuracy and reliability.

InSAR is a sophisticated satellite technology which detects ground deformation with remarkable precision. 

The process involves comparing multiple radar images, taken from the same location over time. Detecting shifts in the ground with millimetric precision, this technique is particularly valuable for continuous monitoring.

Key benefits of InSAR include:

• High precision in measuring ground movement

• High frequency, with SAR satellite passes typically every six days 

• Ability to cover large, inaccessible areas

• Non-invasive monitoring

• Cost effective, reducing expenses related to traditional ground methods

Tailings dam displacement monitoring using InSAR

InSAR technology enables the detection of ground deformation across extensive areas, offering insights into geotechnical conditions that were previously difficult to capture. 

By enhancing spatial coverage and data continuity, InSAR technology provides a more comprehensive understanding of tailings facility behaviour and serves as a powerful complement to conventional monitoring methods.

The value of historical InSAR data for tailings dams

One of the most valuable advantages of InSAR lies in its ability to provide retrospective insight. 

Historical InSAR datasets offer a particularly rich source of information for tailings dam monitoring, delivering a long-term perspective on ground deformation and enabling engineers to identify patterns, trends, and early indicators of instability.

Importantly, historical data analysis enables more accurate predictions of future behaviour, revealing subtle trends that routine monitoring may overlook. These insights are essential for a more proactive and informed approach to risk management.

By capturing continuous, high-resolution measurements, it deepens understanding of dam stability and effectively bridges the gaps left by periodic manual inspections.

Key benefits of historical InSAR data include:

• Enhanced prediction of potential failure points

• Comprehensive validation of geotechnical models

• Support for regulatory compliance through documented monitoring

  
  

Revealing hidden risks: Case study examples from historical InSAR 

Historical InSAR data has revealed significant, previously undetected risks across multiple case studies digging into failures and why they occurred, offering deeper insight into failures and their underlying causes.

A notable example is the partial collapse of Australia’s Cadia Valley Northern Tailings Storage Facility (NTSF), part of a gold and copper mining complex. On 9 March 2018, a section of the tailings dam collapsed, releasing tailings into the adjacent Southern TSF. 

The incident prompted questions about whether such a collapse could have been predicted and prevented through regular satellite-based monitoring. Geofem focused on leveraging Interferometric SAR (InSAR) data to track ground movement over time, assessing whether early warning signs could have been detected to avert the failure.

InSAR analysis of Sentinel-1 descending SAR data revealed ground movement at the site of the collapse and exposed gradual subsidence that was not detected by traditional methods.

A plot of displacement versus time showed that the ground had been shifting consistently for two years, with a significant acceleration occurring after 8th January 2018. During this period, the velocity increased from an average of 45 mm/year to 90 mm/year by February 2018—double the previous rate. By 25th February 2018, the velocity surged to 214 mm/year, more than doubling again.

Integrating historical InSAR with traditional monitoring 

Incorporating historical InSAR data with traditional monitoring techniques enhances key insights. By overlaying satellite observations with on-the-ground measurements, a more comprehensive view is achieved. This fusion provides a multi-faceted understanding of tailings dam dynamics. 

A combined monitoring approach benefits from the strengths of each method – a synergy that allows for informed decision-making based on both immediate conditions and long-term patterns.

Geofem leverages historical InSAR analysis to deliver comprehensive deformation insights, enabling a more holistic assessment of risk. This empowers senior engineers to identify potential issues at an earlier stage, supporting a proactive approach to safety and operational management, while also helping to ensure regulatory compliance.

Looking ahead: The future of tailings stability 

The future of tailings monitoring lies in combining historical datasets with advanced analytics to improve prediction and early warning. As regulatory expectations increase, the ability to demonstrate long-term understanding of asset behaviour will become essential.

InSAR data, combined with AI and machine learning, promises enhanced predictive capabilities, while historical InSAR data offers a unique advantage for understanding tailings dam behaviour over time. By leveraging past data, engineers can more effectively predict future issues, improving safety measures significantly.

By enabling proactive risk management, these innovations not only safeguard critical assets but also enhance the protection of surrounding communities and ecosystems, marking a shift towards long-term sustainability. Ultimately, leveraging historical insight to inform decision-making reinforces the mining industry’s commitment to safety, responsibility, and sustainable stewardship.

Want to understand how historical InSAR can support your tailings facility? We can quickly assess your site and demonstrate where risks may already be developing.

Geofem is a leading provider of InSAR services and combines advanced data analysis with deep engineering expertise to deliver clear, actionable reporting and consultation—empowering you to detect risk earlier, make confident decisions, and ensure safer, more resilient operations.