Onset Time Determination of Acoustic and Electromagnetic Emission During Rock Fracture

We present an application of the Akaike Information Criterion (AIC) for an automatic and accurate determination of the acoustic and electromagnetic emission (AE and EME) onset times. The onset time information is used to derive the time delays between correlated AE and EME events from rock specimens during laboratory fracture experiments. The observed correlation in time between AE and EME events is consistent with EME release during microcrack growth. Relevant load drops are accompanied by AE bursts, expected to be generated during macrocracks propagation