Preliminary analysis of acoustic emission characteristics during stick slip and stable sliding of halite gouge fault zone

In this paper, the frictional sliding characteristics of wet halite gouge are studied by using biaxial friction configuration, the acoustic emission (AE) characteristics during the process of sliding are observed and analyzed, also the microstructure of the fault zone is studied by scanning electron microscope (SEM). The results show that a lot of AE events occur in the velocity weakening process with stick-slips and also occur in the velocity strengthening process with stable sliding. The small AE events occur in the stick-slip process and the stable sliding process has some common features, that is, both of them show low energy levels. The dominant frequencies of the small AE events in the stick-slip process include low frequency (about 10 kHz), medium frequency (about 100 kHz) and high frequency (about 370 kHz). However, in the stable sliding process, AE activity is dominated by low frequency and medium frequency events, lacking high frequency events. The difference is closely related to the difference of the dominant deformation mechanisms. During stick-slip cycle, when approaching the friction peak, AE occurrence rate of low and medium frequency events increases significantly, but the high frequency events decrease. After entering the meta-instability stage, the dominant frequency of AE events has only low frequency and medium frequency, and almost no high frequency. This difference is closely related to the change of deformation mode of the fault zone.