People near Marrakesh, Morocco, shared videos recorded before the 6.8-magnitude earthquake that struck the area on Friday, showing not recognized lights in the sky. The strange aerial phenomena are known as earthquake lights, and seem to occur above areas of seismic stress.
“People have wondered about them forever,” said Karen Daniels, a physicist at North Carolina State University. “It’s one of those ongoing mysteries that remains and has never been solved.”
Earthquake lights are difficult to study because earthquakes are impossible to predict. Without knowing when or where this will happen, researchers don’t know where to place sensitive equipment that might detect them. Some experts doubt that they are related to earthquakes, according to the United States Geological Survey.
But accounts of these lights go back centuries, said John Ebel, a seismologist at Boston College who wrote a book on the history of earthquakes in the northeastern United States. In a study in 2014, researchers discovered reports of aerial luminous phenomena from 65 earthquakes that occurred in Europe and America during the 18th, 19th and 20th centuries.
People have reported various types of earthquake lights, from bright ones high in the sky to low on the horizon. Some last up to minutes, others flash and flash like lightning. They have also been seen in different colors.
“All of this was reported by observers,” said Dr. Ebel. “Which of these are really true, and which are the products of their imagination, we cannot say.”
The advent of dash cams, smartphones and social media provided the first non-anecdotal data. Videos of earthquake lightsfor example, caused chaos during the 2021 earthquake in Guerrero, Mexico.
One hypothesis for how earthquake lights are generated is that friction between tectonic plates generates electricity. But experts question that idea, because it usually results from two different materials rubbing together and pulling electric charge away from each other.
“Rock on rock is not a situation where people have developed a large charge separation,” said Dr. Daniels. “And so it’s not a very good explanation for what people are seeing.”
Other explanations could be electrical arcing from power lines shaken by earthquakes, said Dr. Daniels. But he and other experts do not rule out the possibility that there is no connection between the lights and tectonic events.
“We are comforted by things we understand, and we fear things we don’t,” said Dr. Daniels. “I think that’s part of the reason we’re fascinated by this phenomenon.”
