They've been mistaken for UFOs or dismissed as hallucinations. Now geologists have collected a near-definitive list of a rare but fascinating phenomenon — earthquake lights.
Certain types of earthquakes in certain areas can set off blazes of light seconds — sometimes days — ahead of the actual quake. These can manifest themselves as floating balls of light, bluish columns shooting up out of the earth and even reverse lightning, reaching up into the sky from the ground.
A study out Thursday in the journal Seismological Research Letters shows such quakes are tied to a specific type of temblor in areas where certain geological formations occur.
While rare, researchers were able to document 65 examples between 1600 and the present.