The reports of “seismic lights” in the recent earthquake in Morocco brought one back to the fore concern scientists as opinions differ on what causes them. In fact, these references go back to ancient Greece.

They bursts of bright, dancing light in different colors have long puzzled scientists but are “definitely true”said the John Derra retired geophysicist who worked at the US Geological Survey and who has authored several scientific papers on earthquake lights, or EQLs.

“Their visibility depends on darkness and other factors”explains while mentioning that recent video from Morocco shared online looked like a similar one that captured earthquake lights as captured by security cameras during a 2007 earthquake in Pisco, Peru.

Seismic lights can take different forms, according to Derr’s paper on the phenomenon, published in the 2019 edition of the Encyclopedia of Solid Earth Geophysics.

Sometimes, the lights may look similar to ordinary lightning or it may be like a bright band in the atmosphere similar to the aurora borealis. Other times they look like glowing orbs flying through the air. They may also look like small flames flickering or creeping along or near the ground or larger flames emerging from the ground.

To better understand seismic lights, Derr and colleagues compiled information on 65 American and European earthquakes for which there are reliable reports of seismic lights dating back to the 1600s.

The researchers found that about 80% of the seismic light events studied were observed in earthquakes with magnitudes greater than 5.0 on the Richter scale. In most cases, the phenomenon was observed shortly before or during the seismic event and was visible up to 600 kilometers (372.8 mi) from the epicenter.

Earthquakes, especially strong ones, are more likely to occur along or near areas where tectonic plates meet. However, the 2014 study found that the vast majority of earthquakes associated with seismic lights occurred within tectonic plates rather than at their boundaries.

Furthermore, seismic lights were more likely to occur in or near fault valleysplaces where, at some point in the past, the Earth’s crust has moved away, creating an elongated lowland area that lies between two higher pieces of land.

Possible causes of seismic lights

Regarding the causes that cause the phenomenon, NASA researcher Friedemann Freund has come up with a theory that when certain defects or impurities in crystals in rocks subjected to mechanical stress, such as during the build-up of tectonic stresses before or during a large earthquake, they break apart immediately and produce electrical