Source Location and Dataset Incompleteness in Acoustic Emissions from Ice Tank Tests on Ice-Rubble-Ice Friction

Abstract

Experiments in rock mechanics conducted in the laboratory have revealed that the generation of elastic waves during micro-fracturing provide a small-scale analogue to seismogenic processes. These elastic waves are called acoustic emissions (AE). In contrast to rock, the seismic behaviour of ice under applied stresses is relatively unstudied and a robust statistical categorisation of acoustic events has not yet been performed. In analogy with experiments from rock mechanics, where it has been proven that statistical laws of seismicity are obeyed in AE events, we aim to characterise seismic activity in ice. This was done by measuring acoustic emissions during ice-rubble-ice friction tests conducted at the HSVA ice tank. Specifically, we studied AE data from two tests which used different rubble geometries: large round and small angular. Using these datasets from we first conduct source location of the AE activity. Secondly, we investigate the possibility of incompleteness in the AE datasets during periods of increased activity. Our results from source location show that the round rubble geometry gave higher acoustic activity at the sliding interfaces. We observe potential incompleteness in both datasets. This analysis has applications in field of seismology as well as in ice mechanics.