Acoustic and electromagnetic emissions in rocks under compression

The present paper focuses on Acoustic Emission (AE) and Electromagnetic Emission (EME) detected during laboratory compression tests. We investigated the mechanical behaviour of granite rock (Luserna stone) specimens with different size and shape. The recorded AE and EME signals were related to the time history of the load applied to the specimens. The results show the frequency range in which the EME due to fracture phenomena take place. In addition, the experimental evidence demonstrates how AE can be considered as a fracture precursor, since it precedes EME events, which accompany stress drops and related discontinuous fracture advancements.