13. Earthquake Lights
Occasionally, rare flashes or glows—known as earthquake lights—are seen just before or during seismic events. These mysterious lights have been reported on different continents, but their origin is still debated. Possible explanations include electrical discharges in the atmosphere or frictional effects within rocks, yet no single theory fits every occurrence. The phenomenon continues to intrigue geologists and witnesses alike. Find more information at USGS.