Identification of the meta-instability stage via synergy of fault displacement: an experimental study based on the digital image correlation method

Publication date: Available online 21 March 2015 Source:Physics and Chemistry of the Earth, Parts A/B/C Author(s): Yan-Qun Zhuo , Jin Ma , Yan-Shuang Guo , Yun-Tao Ji In stick-slip experiments modeling the occurrence of earthquakes, the meta-instability stage (MIS) is the process that occurs between the peak differential stress and the onset of sudden stress drop. The MIS is the final stage before a fault becomes unstable. Thus, identification of the MIS can help to assess the proximity of the fault to the earthquake critical time. A series of stick-slip experiments on a simulated strike-slip fault were conducted using a biaxial servo-controlled press machine. Digital images of the sample surface were obtained via a high speed camera and processed using a digital image correlation method for analysis of the fault displacement field. Two parameters, A and S, are defined based on fault displacement. A, the normalized length of local pre-slip areas identified by the strike-slip component of fault displacement, is the ratio of the total length of the local pre-slip areas to the length of the fault within the observed areas and quantifies the growth of local unstable areas along the fault. S, the normalized entropy of fault displacement directions, is derived from Shannon entropy and quantifies the disorder of fault displacement directions along the fault. Based on the fault displacement field of three stick-slip events under different loading rates, the experimental resul...

Source: Physics and Chemistry of the Earth, Parts ABC - March 22, 2015 Category: Science Source Type: research