Synchronization of multifractal properties of continuous acoustic emission during the preparation and implementation of dynamic slip in model fault

Abstract

According to the stick-slip model, the relative movement of the fault planes is an act of unstable sliding, where movement begins when the stresses tangential to the fault plane reach a certain limit. The physical mechanism of dynamic slip along a fault consists of the sequential formation of conglomerates of loaded particles (force chains) in the contact zone and their subsequent destruction. These chains together form a force skeleton characterized by a specific spatial structure and strength properties. An increase in shear stress on the fault banks leads to local destruction of the strength skeleton; further evolution of the system brings destruction processes to higher spatial levels, ultimately leading to a shift in the fault banks. Since the evolution of the process of destruction of force chains in the contact zone of a fault along the hierarchy of scales from bottom to top is similar to the evolution of crack formation in a loaded medium from microscale to macroscale (specimen scale), the authors hypothesized the coherent behavior of acoustic noise accompanying the preparation of dynamic slip and recorded in different areas of fault zones. This work is devoted to testing this hypothesis on a laboratory scale, using an installation that simulates movement along a fault. As a result of the analysis, the hypothesis about the synchronization of the statistical properties of the acoustic emission during the preparation and implementation of the dynamic movement was confirmed. It is shown that the observation (detection) of the effect of the synchronization of the statistical properties of acoustic emission depends both on the set of parameters for which the spectral coherence measure is calculated and on the location of the recording of the initial data.

Keywords

• model fault
• acoustic emission
• synchronization
• multifractal properties