Jiefang Song published a paper in Gephysical Research Letters Entitled “Laboratory Acoustic Emissions Reveal Stress Rotation From Preparation Processes Toward Fault Slip on Varying Surface Roughness in Granular Materials”. In this study, Jiefang studies how the surface roughness of a fault affects the physical damage that occurs before large laboratory earthquakes and how the stress field around the fault zone evolves. He used laboratory fault friction experiments on sandstone containing smooth and rough fault and analyze sub-mm scale acoustic emission events observed during the loading process. He implemented different types to stress inversion of focal mechanisms to resolve the local stress evolution over the fault surface subjected to loading. He found that thet local stress rotates, irrespective of the fault roughness.
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