We show that the inequality in the divergent acoustic energy release rate in quasistatically compressed nanoporous materials can be used as a precursor to failure. A quantification of the inequality in the evolution of the energy release rate using social inequality (such as Gini and Kolkata) indices can predict large bursts of energy release. We also verify similar behavior for simulations of viscoelastic fiber bundle models that mimic the strain-hardening dynamics of the samples. The results demonstrate experimental applicability of the precursory signal for fracture with a diverging energy release rate using social inequality indices.