Mysterious lights appear to have been spotted in Morocco before a devastating earthquake hit last week – and scientists still can't figure out what caused them.

A 6.8-magnitude earthquake hit the High Atlas Mountains in Eastern Morocco on Friday. At least 2,900 people have died and about 5,500 are reported injured, Reuters said on Tuesday.

People have taken to social media to discuss videos that appear to show bright flashes of light streaking across the sky before the earthquake hit.

Insider was unable to independently verify the videos, but experts believe they could have recorded an aerial phenomenon known as "earthquake lights."

No one knows for sure if earthquake lights exist, or what causes them. However, if these lights are proven to be linked to powerful seismic activity, some scientists hope they could be used to help with early detection efforts.

'Earthquake lights' were long relegated to old folk tales

There is a smattering of records reporting bursts of light linked to earthquakes that date back centuries.

Reports range from bright second-long flashes to minute-long fireballs, either high or low in the sky, of different colors, per The New York Times.

Because you can't predict when an earthquake will happen, it's impossible to carry out a study to document these events firsthand. So scientists long had to rely on people's memories — which are notoriously fallible.

"People have wondered about them forever," Karen Daniels, a physicist at North Carolina State University, told The New York Times. "It's one of those persistent mysteries that hang around and never quite get nailed."

Because of this, earthquake lights had been thought to be a myth. But with the advent of security cameras and handheld phones, more footage has started to add weight to the belief that they do happen.

For instance, mysterious bright flashes were caught on camera before the 2021 earthquake in Mexico City, PBS reported. They also appeared over eastern Japan before a 2022 earthquake, The Guardian reported at the time.

There's now more evidence to suggest these flashes do on occasion happen around earthquakes. But the question remains: What is happening?

Are these earthquake harbingers, or something else?

The short answer is that we just don't know.

Geophysicist Friedemann Freund of the SETI Institute worked on a paper reviewing 65 reports of potential "earthquake lights" collected since the 1600s. He believes earthquake lights could be an elaborate form of static electricity.

As tectonic plates rub together, he told The Washington Post, this friction could create enough current to produce an electric discharge, which would explain the bright flash.

But Daniels told The Times she disagrees with this explanation.

"Rock on rock is not a situation where people have been able to generate large charge separation," she said. "And so it just doesn't seem like a very good explanation for what people see."

The US Geological Survey (USGS) is similarly cautious about its interpretation of the events.

"Geophysicists differ on the extent to which they think that individual reports of unusual lighting near the time and epicenter of an earthquake actually represent earthquake lights," per the USGS website.

"Some doubt that any of the reports constitute solid evidence for EQL, whereas others think that at least some reports plausibly correspond to EQL," the website continues.

There are other potential explanations for the flashes. It's possible, for instance, that early tremors shake power lines, creating arcs of electricity.

Still, Daniels doesn't exclude the possibility that the flashes could be linked to the earthquakes, she told The Times.

"We're comforted by things that we can understand, and we're scared by things we don't," she said, per The Times. "I think that's part of the reason we're so fascinated by this phenomenon."

This article was originally published by Business Insider.

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