Seeing Inside a Tailings Dam: How GroundIQ® Helped Rule out Hidden Structural Risks
As part of Fugro’s GroundIQ® solution, we applied our adapted 3D Ambient Noise Tomography (ANT) technology to rapidly assess the internal condition of Codelco’s Colihues Tailings Deposit in Chile and support safer, more informed risk management.
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Codelco is the world's largest copper producer and one of Chile's most important mining companies. The company operates several large-scale mining sites across the country, where the safe management of critical infrastructure such as tailings storage facilities is a key operational priority.
Impact at a glance
Project Overview
Tailings dam safety is a major global concern. With more than 3,500 facilities worldwide and a history of high-impact failures, understanding the condition of these structures over time is essential. Codelco’s Colihues and Cauquenes tailings storage facility (TSF) is part of the El Teniente mine in central Chile, around 90 kilometres south of Santiago. Within this complex, Dam A, a downstream-constructed facility, was the focus area for this study. Mining operations were active during the investigation period.
Since tailings dams are complex structures, getting an accurate picture of what’s happening inside them can be quite challenging. At Dam A, several factors made it especially difficult to characterise internal conditions using conventional investigative methods.
"When you're relying on boreholes alone, you're only seeing isolated points. The challenge is understanding everything in between, especially in a structure as large and complex as Dam A."
GroundIQ® proposed a geophysical screening solution to create a complete 3D view of Dam A’s internal structure. Using ANT, seismic vibrations from natural and operational sources would be transformed into a 3D volume of shear wave velocity, a key indicator of material stiffness.
This would allow Codelco to visualize the stratigraphy of the dam, assess its foundation, and identify low-velocity zones that are indicative of significant risks, such as internal erosion, seepage, or loss of strength. The resulting 3D model would then form a foundation for safer, more informed tailings dam management, and could be validated and refined using existing borehole data.
To implement the proposed approach, GroundIQ® combined passive and active seismic techniques across Dam A, capturing vibrations from natural and operational sources over several days.
These measurements were used to create a detailed 3D picture of the dam’s internal structure.
The collected data was processed to generate a 3D model of shear wave velocity, which reveals internal layering, highlights any potentially weak zones, and supports engineering and safety decisions.
Existing borehole data were used to validate the model and increase confidence in the results.
"By combining passive and active seismic methods, we were able to develop a continuous 3D understanding of the dam while keeping field operations safe and minimally intrusive."
GroundIQ® delivered a 3D ground model of Dam A within four weeks, providing Codelco with a detailed view of the dam’s internal structure to depths exceeding 100 metres.
The ground model revealed two primary layers within the dam: fluvial deposits and moraine overlying volcano-sedimentary rock soils. Importantly, no weak zones, typically evidenced by shear wave velocities below 300 m/s, were revealed, confirming favourable conditions for the dam’s stability. This insight was critical, as undetected weaknesses in tailings facilities can result in significant operational disruption and, in extreme cases, catastrophic failure.
ANT results aligned closely with borehole logs, downhole seismic data, and 2D MASW profiles, validating both the accuracy and the superior spatial coverage of the 3D approach.
This clarity provided Codelco with a high level of confidence in the current stability of Dam A and a reliable basis for proactive risk management.
This project shows how GroundIQ® helps operators move from uncertainty to confidence. By rapidly producing a validated 3D view of Dam A’s internal conditions and confirming that no critical weaknesses were present, Codelco gained clear evidence to support safe operations and informed planning. The study highlights the value of early, data-rich geophysical screening in improving decision-making for complex tailings facilities.