Ubiquity of avalanches: Crackling noise in kidney stones and porous materials

Systematic advances in the resolution and analytical interpretation of acoustic emission (AE) spectroscopy have, over the last decade, allowed for extensions into novel fields. The same dynamic failure patterns, which have been identified in earthquakes, magnetism, and switching of ferroelastic and ferroelectric materials, are shown, in this paper, to be equally important in medicine, and minerals, in the geological context, to give just two examples. In the first application, we show that biological samples, i.e., kidney stones, can be analyzed with acoustic emission and related to the progression of mechanical avalanches. Discrepancies between strong and weak AE signals are shown to have separate avalanche exponents for a urate kidney stone, with evidence of slight multi-branching. It is proposed that investigations of this nature can be adopted to the field of medicine, and in the case of kidney stones, can provide a blueprint for selecting ideal combinations of energy and frequency to instigate their destruction. In a second example, porous geological material failure is shown to proceed equally in avalanches, and precursors to catastrophic failure can be detected via AE. Warning signs of impeding macroscopic collapse, e.g., in mining activities, show systematic evolution of energy exponents. Ultimately, this behavior is a result of geological processes, man-made bio-mineralization, or the burning of carbon inclusions, creating pores and holes, causing cracks, and accelerating their interactions.