1679 weights for socio-environmental criteria and to define the structure of an integrated socio-environmental risk indicator, based on a group-aggregated pairwise comparison matrix. 3.1 Criteria definition The AHP is used to structure and prioritize socio-environmental criteria relevant to strategic decisions associated with the transition from open-pit to underground mining. The hierarchy considered corresponds to a single-level hierarchy consisting of one goal and six criteria, defined as: (C1) surface disturbance, (C2) extreme climate events, (C3) energy consumption, (C4) mine-to-water-resources distance, (C5) mine-to-population-centers distance, and (C6) distance between water resources and population centers. This structure enables the derivation of relative weights through pairwise comparisons and the generation of a traceable ranking of the relative importance of the criteria. These criteria were selected based on the conceptual framework developed in the Introduction, which identifies critical dimensions for the sustainability and socio-environmental feasibility of strategic transition decisions: (i) the magnitude of surface intervention, (ii) exposure to climate hazards, (iii) energy dependence and its link to emissions, and (iv) contextual sensitivity associated with proximity to water resources and population centers. Taken together, the six criteria operationalize these dimensions into comparable variables within the AHP framework. 3.2 AHP implementation: expert elicitation, aggregation, and weight estimation Relative preferences among criteria were elicited through expert judgment by asking participants to perform pairwise comparisons across the six criteria. Saaty’s fundamental 1–9 scale was adopted, where 1 denotes equal importance and 9 denotes extreme importance of one criterion over another; intermediate values represent increasing levels of preference (Table 1) (Saaty, 1977; Saaty & Tran, 2007). For each expert >, a pairwise comparison matrix }(+) =ñk) ( * +)ô of size Å×Å (with Å=6) was constructed, where k ) ( * +)expresses the importance of criterion Trelative to criterion Á. These matrices satisfy the reciprocal property k* ( ) +) =1/k) ( * +)and k) ( ) +) =1. Table 1 - Saaty’s fundamental 1–9 scale for pairwise comparisons (Saaty, 1977). Intensity of Importance Definition 1 Equal importance 3 Weak importance of one over another 5 Essential or strong importance 7 Very strong or demonstrated importance 9 Absolute importance 2,4,6,8 Intermediate values between adjacent scale value Because the study relies on multiple experts, individual matrices were aggregated into a group matrix }¯ = ñk¯)*ô using the element-wise geometric mean, a standard procedure in group-AHP due to its consistency with ratio-scale judgments and its preservation of reciprocity. In total, ï=8 experts from both the mining industry and academia were surveyed, all with more than 10 years of professional experience. Their profiles span complementary domains relevant to the decision problem, including mine planning and operations, environmental management and sustainability, social and territorial/community aspects, climate risk and operational continuity, energy and efficiency, and geotechnics. The aggregation is defined as:
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