Strange light phenomenon seen before some earthquakes is a long-standing mystery. Here’s what scientists think it means | CNN
www.cnn.com
Reports of “earthquake lights,” like the ones seen in videos captured before Friday’s 6.8-magnitude earthquake in Morocco, go back centuries to ancient Greece.

Earthquake lights can take several different forms, according to a chapter on the phenomenon coauthored by Derr and published in the 2019 edition of the Encyclopedia of Solid Earth Geophysics.

Sometimes, the lights may appear similar to ordinary lightning, or they may be like a luminous band in the atmosphere akin to polar aurora. Other times they resemble glowing spheres floating midair. They may also look like small flames flickering or creeping along or near the ground or larger flames emerging from the ground.