Laboratory Observations of Repeated Interactions between Ruptures and the Fault Bend Prior to the Overall Stick-Slip Instability Based on a Digital Image Correlation Method

Abstract

Fault geometry plays important roles in the evolution of earthquake ruptures. Experimental studies on the spatiotemporal evolution of the ruptures of a fault with geometric bands are important for understanding the effects of the fault bend on the seismogenic process. However, the spatial sampling of the traditional point contact type sensors is quite low, which is unable to observe the detailed spatiotemporal evolution of ruptures. In this study, we use a high-speed camera combined with a digital image correlation (DIC) method to observe ruptures during stick-slip motions of a simulated bent fault. Meanwhile, strain gages were also used to test the results of the DIC method. Multiple cycles of the alternative propagation of ruptures between the two fault segments on the both sides of the fault bend were observed prior to the overall failure of the fault. Moreover, the slip velocity and rupture speed were observed getting higher during this process. These results indicate the repeated interactions between the ruptures and the fault bend prior to the overall instability of the fault, which distinguishes the effect of the fault bend from the effect of asperities in straight faults on the evolution of ruptures. In addition, improvement in the temporal sampling rate of the DIC measurement system may further help to unveil the rupture evolution during the overall instability in future.

New Approach to Strong Earthquake Prediction in the South Baikal Region on the Basis of Rock Deformation Monitoring Data: Methodology and Results

“…The experimental data show that tremors take place at the meta-instability stage, i.e. when a displacement along the rupture is being generated [Ma et al, 2014;Zhuo et al, 2019]. Depending on the duration of this stage in nature, the tremors can be considered as intermediate and/or shortterm precursors.…”

“…Considering natural faults, we suggest that the self-organization process can be diagnosed by a digital analysis of the time series of rock deformation signals. We have tested this research approach by spectral analysis [Scargle, 1982[Scargle, , 1989Savransky, 2004;Bornyakov et al, 2017], entropy analysis [Brillouin, 1966;Zubarev et al, 2002;, and fractal analysis [Mandelbrot, 1982;Velde et al, 1990], and the structural functions curvature analysis method (SFCAM) [Vstovsky, 2006[Vstovsky, , 2008Bornyakov, Vstovsky, 2010].…”

Special Issue on Advances in Digital Image Correlation (DIC)

“…The response of copper plates subjected to impulsive loading in complex fluid-structure environment, studied in [2] using high-speed stereo-DIC, illustrates the wide range of time scales that can be addressed by DIC. Along the same line, high-speed camera based DIC was used in [3] to observe ruptures during stick-slip motions of a simulated earthquakes. Still in the field of geomechanics, paper [4] measured earth surface dynamics and investigated the issue of application of DIC under severe environmental and lighting conditions and at very large space scales.…”