Abstract
The mechanical and statistical characteristics of acoustic emission (AE) events during stable sliding are investigated through a laboratory experiment using a granite specimen with a pre-cut fault. Numerous AE events are found to be generated on the pre-cut fault, indicating that microscopically unstable fracture occurs during macroscopically stable sliding. The composite focal mechanism solution of AE events is determined from the first motion directions of P-waves. The determined mechanism is consistent with the double-couple one expected for the slip on the pre-cut fault. The source radii of large AE events are estimated to be about 10 mm from the widths of the first P-wave pulses. These indicate that the AE events are generated by shear fracture whose faulting area is a part of the pre-cut fault plane. The occurrence of AE events as a stochastic process approximately obeys the Poisson process, if the effect of mutually dependent events constituting clusters is corrected. The observed amplitude-frequency relation of AE events approximately follows a power law for a limited amplitude range. As the macroscopic sliding rate increases, the number of AE events per unit sliding distance decreases. This rate dependence of the AE activity is qualitatively consistent with the observation that the real area of contact between sliding surfaces decreases with an increase in the sliding rate as reported in the literature.
Original language | English |
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Pages (from-to) | 1163-1189 |
Number of pages | 27 |
Journal | Pure and Applied Geophysics |
Volume | 160 |
Issue number | 7 |
DOIs | |
Publication status | Published - 2003 Jul 1 |
Keywords
- AE activity
- Friction
- Micro fracture
- Rate dependence
- Stable sliding
ASJC Scopus subject areas
- Geophysics
- Geochemistry and Petrology