One of the strongest earthquake illuminations came during Chinese earthquake of 1976. Lights at the center of the earthquake were bright enough to turn night into day. Charlotte, North Carolina area reported seeing a bright flash when the area north of Charlotte was hit by a 3.2 magnitude earthquake. Earthquake Lights are like caused by the piezoelectric effect in quartz-bearing rock. Quartz has the unique attribute of emitting electricity under pressure.
Experiments show quartz can produce light emissions of short duration.
Earth Lights are often reported in areas of seismic stress. Reports of strange moving lights in areas near fault lines are common. The stress may also release ionized gas the air that is ignited by the electrical flashes. Although, these lights may be the cause of some UFO reports, they are fairly rare along the Pacific Rim where most of the Earthquakes happen. Even more important, the Earthlights theories fail to explain any metal and structured object or occupant reports.