According to articles published by businessinsider.com and the New York Times, videos shared on social media seem to show earthquake lights streaking across the sky before a M 6.8 earthquake hit the High Atlas mountains in eastern Morocco on Friday evening, September 8.
Earthquake lights are allegedly luminous phenomena observed before, during or after a strong earthquake. They are described as short-lasting lights, like flashes, glowing clouds and orbs or even flames coming from the ground.
For a long time, only anecdotal accounts and tales existed and most seismologists didn’t take accounts of earthquake lights seriously. In 1973, Japanese geologist Yutaka Yasui provided some disputed photographic evidence, supposedly showing glowing reddish and blue clouds in the sky above the city of Matsushiro during a series of earthquakes.
Based only on the videos found online, the bursts of light seem to me more likely caused by electric arcs between power lines as they swing and exploding infrastructure (like transformers) in the city’s streets.
In 2017 and 2021, when the strongest earthquake in decades hit Mexico City, images and videos showing luminous phenomena in the sky quickly went viral but later were exposed as electric sparks reflected by the cloud cover. Supposed earthquake lights reported during the Turkey-Syria earthquake in 2023 were a combination of lightning during a thunderstorm, electric discharges and fires ignited by explosions.
Even if there is no proof of earthquake lights so far, they are not outside the realms of extreme geological possibilities. Electromagnetic effects in Earth’s atmosphere can produce glowing phenomena. A temporary electromagnetic field could also explain reports of malfunctioning electronic devices (especially telephones) during an earthquake. According to this theory, in tectonically active regions, electric charges can accumulate over time in the deformed rocks. A part of this electric energy is released during an earthquake, causing a visible spark and explaining small, short-lived flashes. The accumulated electric energy can also ionize oxygen atoms in the underground. Following faults, the oxygen ions will rise to the surface as glowing cloud.
The epicenter of Morocco’s devastating earthquake (over 2,500 victims so far) was located at a shallow depth between 8 and 26 kilometers in the High Atlas Mountains, about 71 kilometers southwest of Marrakesh.
This area doesn’t usually have a lot of earthquakes compared to other places near the edges of tectonic plates, where the movements of plates will cause intense seismic activity.
In Morocco, earthquakes are related to reactivated faults formed over 250 million years ago by the break-up of the Pangaea supercontinent. During the break-up and opening of the Atlantic, a rift-structure bordered by parallel normal faults formed in the Paleozoic rocks, filled later by Mesozoic limestone deposits. About 65 million years ago, the rotation of Africa and collision with Europe caused the rift to close, reactivating the normal faults as reverse faults. Deformation along the reverse faults is still going on as the Atlas Mountains are getting pushed together at a rate of about 1 millimeter each year.