摘要：Reports on the sky being brightly illuminated before, during, or after large earthquakes have existed for many centuries.Physical processes behind this phenomena, however, has not been fully explained despite large public interest in this phenomena.In this report, we present photographic evidence that visible light is emitted from faults.We observe luminescence that occurs simultaneously with the brittle faulting, and spatial distribution of the luminescence coincides the faulting pattern.This luminescence consists of several colors and is recordable with commercial digital cameras.In our experimental setting, it was observed only during fracture of granite, and we postulate that piezoelectricity of quartz in granite plays a major role in its occurrence.
