Characteristics and Implications of Nanocoatings on Gouges in a Seismically Active Fault Zone.

Using a ZEISS Axio Scope A1 ordinary polarizing microscope, a ZEISS Sigma 300 scanning electron microscope and a HITACHI S4800 scanning electron microscope, we observe micro/nanocharacteristics of slip planes in gouges sampled from the Tanlu fault zone, the Haiyuan fault zone and several other Late Pleistocene active faults, such as the Haiyang fault, the Shuangshan-Lijiazhuang fault and the Xintai-Mengyin fault, in Shandong Province. Based on microscopic observation of gouges, a straight slip zone is a sign of seismic stick slipping. According to scanning electron microscopy results, the surface of gouges is commonly covered by nanocoatings. Such coatings feature nanoparticles, aggregations, scratches, grooves, cracks and "silver lines." According to the characteristics of nanomaterials, we believe that nanocoatings on gouges could help rapidly unload tectonic stress in the process of energy accumulation and weaken the strength of the active fault, which is beneficial to creep slipping and has a weakening effect on seismogenesis.