Ambient Seismic Noise Imaging for Tailings Storage Facilities Monitoring: a Benchmark between Accelerometers and DAS
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There have been many recent examples of tailings dam failures that have led to catastrophic consequences such as loss of life, pollution or damage to the ecosystem (e.g., the Jagersfontein tailings dam failure in South Africa in September 2022 and the Williamson tailings dam failure in Tanzania in November 2022). One important factor affecting the stability of tailings storage facilities (TSFs) is the presence and movement of water within the facility. Dam failures are often caused by seepage or the presence of weak layers within the tailings dam or the foundation soil. Thus, monitoring for the presence or movement of water within TSFs is becoming increasingly important, and solutions for permanent, non-intrusive and cost-effective monitoring of dams are a major challenge. One such solution is represented by geophysical imaging techniques such as ambient seismic noise interferometry [1]. A nodal network system of accelerometers sensors was deployed in a dense and random array on a TSF embankment wall at an Australian mine. Simultaneously, a fiber optics cable was deployed in a trench at the top of the TSF. Ambient seismic noise was recorded over a few weeks using the nodal network and with the fiber optics cable over several months using Distributed Acoustic Sensing (DAS). Following data acquisition, benchmarking passive seismic imaging from the accelerometer network and the DAS system [2] was conducted to evaluate the DAS capabilities for TSF long-term monitoring. This paper presents benchmarking tests of the sensor networks that can be used for monitoring TSFs. It presents a potential solution for permanent monitoring, which is currently being trailed at a Gold Mine in Western Australia, namely fiber optic sensing using Distributed Acoustic Sensing (DAS) technology.