These are mostly white or bluish flashes that precede large earthquakes and last for several seconds. They have been reported infrequently for hundreds of years, according to the U.S. Geological Survey. It wasn't until the 1960s, when people took pictures of this phenomenon during the Matsushiro earthquakes, that the scientific community started to take it seriously. Since then, scientists have created many theories for the origin of the lights, involving everything from piezoelectricity and frictional heating to phosphine gas emissions and electrokinetics. But most recently scientists suggested that the lights are caused by pre-earthquake elements that awaken the natural electrical charge of rocks, causing them to sparkle and glow.