Abstract
Since the similarity in size distribution of earthquakes and that of acoustic emissions (AEs) was pointed out in 1960s, a number of rock fracture experiments on the temporal evolution of AE activity prior to the final rupture have been conducted. We briefly review these studies mainly focusing on those on the space-time distribution of AEs. Recent development of the experimental technique and the measurement equipment have made it possible to locate sufficient number of AE events for investigating the formation process of final shear fault under triaxial compression. Detailed structure of the fault nucleation zone was revealed by using these AE data, which consists of two portions; the process zone in front of the fault tip, and the damage zone behind it. Evolution of statistical parameters of the spatial distribution of AEs was also studied, and discussions relating to intermediate- and short-term earthquake prediction were made based on the experimental results.
