Experimental evidence of a non-extensive statistical physics behavior of electromagnetic signals emitted from rocks under stress up to fracture. Preliminary results

The application of mechanical stress on a rock sample can induce electromagnetic emissions. Such emissions can be detected experimentally and in principle could be used as precursors of the upcoming failure. Using experimental observations of stress-induced electromagnetic emissions (SIEME), we apply the concepts of non-extensive statistical physics (NESP) to the time intervals between consecutive SIEME. The application of NESP is appropriate to systems such as fracture-induced effects, where non-linearity, long-range interactions and scaling are important. We find that the SIEME energy release distribution and the inter-event time distribution reflect a sub-extensive system with thermodynamic q-values of the order of qE = 1.67 and qτ ≈ 1.7, respectively.