Luminous phenomena, mostly nocturnal lights, are associated with very small earthquakes in southern Washington state. The phenomena seem to be electrical in nature, related to earthquake lights, and tend to occur when the locus of earthquake activity moves across an active fault in an area of compressional stress.
Key words Luminous phenomena - earthquake lights - nocturnal lights - earthquakes - Yakima Indian Reservation - Toppenish Ridge - Washington - seismicity - tectonic stress - geomagnetism - exoelectron - piezoelectric