GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.1 GNGTS 2023 Fault detection from guided waves and tunnel surface waves of in-mine seismic data F. Khosro Anjom 1 , C. Colombero 1 , L.V. Socco 1 , M. Manzi 2 1 Department of Environment, Land and Infrastructure Engineering, Politecnico di Torino, Italy 2 School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa Introduction Constant mineral excavation and depletion of the shallow mines has driven mineral resources exploration to deep mines with rich ore grade. These mines are usually associated with significant growth in cost and energy consumption, as well as increase in geological complexities, such as faults and dykes (Eales and Cawthorn, 1996). The FUTURE project of ERA-NET Cofund on Raw Materials (ERA-MIN3) is a multi- and cross-disciplinary project that aims at developing innovative, environmentally friendly, and cost-effective solutions for deep exploration, mainly in the challenging in-mine environment. The project plans to develop a system for simultaneous and synchronized on-surface, in-mine, and in-borehole data acquisition, using fiber-optic distributed acoustic sensing and wireless sensing technologies. This study is carried out in the framework of FUTURE project to develop a fast, low-cost, and low-impact workflow for detecting and locating discontinuities inside and in the vicinity of the mines. Seismic data from in-mine acquisitions have already proven to carry important information about the media surrounding the mine tunnels and can be used for the recognition of faults and other structural discontinuities (Rapetsoa et al., 2022). Surface waves attenuate less than the body waves and are usually the dominant event in the recordings. As a result, in on-surface surveys they play a key role for the reconstruction of lateral anomalies and structural discontinuities (e.g., Bergamo and Socco, 2014). Colombero et al. (2019) developed a fast and fully data-driven workflow for near-surface detection and location of geological variations, analyzing the propagation of seismic surface waves through four attributes (i.e., energy, energy decay exponent, attenuation coefficient, and autospectrum). The method showed to be effective in various synthetic and real data sets with different levels of complexity. These features make the strategy potentially useful and attractive for in-mine prospections and operations. However, the propagation of seismic waves in the vicinity of mine tunnels is much more complex than in on-surface surveys. All the tunnel walls act as free surfaces and surface waves are expected to be generated along the tunnel direction. Moreover, the drilling of the