Abstract：High LURR values and observations of Accelerating Moment/Energy Release (AMR/AER) prior to large earthquakes have suggested that intermediate-term earthquake prediction is possible. The LURR and AMR/AER have a similar physical origin. Experiments are very important in exploring the deformation and fracture of earth rock. Acoustic emission experiments of rock failure under triaxial stress have been conducted. The technique of acoustic emission is an important approach to reveal the micro-mechanism of deformation and failure of rocks. In order to simulate the rock in the earth crust the specimens were loaded by the combined action of a constant stress，intended to simulate tectonic loading，and a small sinusoidal disturbance stress，analogous to the Earth tide induced by the sun and the moon. Lots of acoustic emission during the entire loading was recorded. Each acoustic emission signal is characterized by the time，the three coordinates of the hypocenter and the amplitude，which is able to indicate the occurrence time，location and magnitude of every damage (micro-crack) in the specimen. In this paper LURR and AER are carried out in detail using the AE records. The results show that high LURR and AER occur before the macro fracture of the specimens. The experimental results confirm that LURR and AER are two macroscopic failure precursors of rock，which could be served as the experimental support of critical point hypothesis and foundation of earthquake prediction.
