We conducted traditional biaxial-direction shear tests for different-size zigzag gouge of simulated faults. The shear stress, acoustic emission (AE) and vibration signals during shearing and slipping through different-size zigzags were recorded and comparatively analyzed. We sheared layers of polymethyl methacrylate (PMMA) at different normal stresses, and constant shear velocity of 2 um/s, laboratory observations of simulated fault with zigzag-type gouge showing repetitive, shear-slip friction events that are reminiscent of earthquakes were verified. Especially, prior to the final failure of zigzag, the dominant spectrum of vibration signal will gradually move from multi-peak high frequency to single-peak low frequency band. Maybe, the work can interpret the shear-slip mechanism of earthquakes and even provide warnings of failure and instability of zigzag gouge fault.
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