Temporal-Spatial Variations of Associated Faulting Inferred from Satellite Infrared Information: A Case Study of the N-S Seismotectonic Zone in China

Abstract

The activity on a fault is not isolated. Motion of one can affect other faults and trigger activities on them. These interacting faults are called associated faults. In this study, with the N-S seismotectonic zone in China as a case, we use satellite infrared information to analyze temporal-spatial variations of associated faulting. The information used is the low-frequency component TLOW of residual land surface brightness temperature derived from satellite infrared data. The result shows that for a certain time period some faults in the study area have similar curves of TLOW with high correlation coefficients, in addition to corresponding relationship between seismicity of them. It indicates that both infrared information and seismicity reflect associated faulting in an area. Besides, there is also a situation that associated faulting is revealed by only the correlation of TLOW curves. It means that there exist correlative relationships of TLOW curves between faults, exhibiting interaction of associated faults, while no corresponding relation in seismicity appears on these faults. Analysis of the temporal-spatial processes of TLOW demonstrates that associated faulting patterns can change with time. For instance, during 1988~1994 the Honghe fault conjoined with the Lanchang-Gengma fault and the Jinshajiang fault to constitute an associated faulting pattern. During 1994~1998, the Honghe fault combined with the Xiaojinhe fault and the Anninghe-Xiaojiang fault to form another associated faulting pattern. Such a temporal-spatial change may be the reflection of reorganization of the local stress fields in the crust. The result of this study shows that satellite infrared information can become a new independent physical parameter for research of fault interaction, and would be of great significance for development of earthquake dynamics and tectonophysics.