Bright lights illuminated the night sky Tuesday during a powerful earthquake near the Pacific resort city of Acapulco that killed at least one person and rocked buildings hundreds of miles away in Mexico City.
The mysterious light show rattled many residents, some of whom shared videos online of the blue flashes. Some used the hashtag #Apocalipsis, Spanish for the “apocalypse,” as the eruption of light coincided with swaying buildings and rockslides.
It’s not the first puzzling light spectacle to coincide with a major earthquake. In 2017, for example, images of green and blue lights appeared on social media following a magnitude 8.1 earthquake in Mexico, National Geographic reported.
Some conjectured that the lights were another instance of earthquake lights, a phenomenon that has baffled experts for years.
Rutgers University physics professor Troy Shinbrot told USA TODAY that earthquake lights, or EQL, are relatively rare but mysterious, long sparking far-fetched theories of UFOs and supernatural spirits. While most earthquakes, even large ones, do not exhibit EQL, Shinbrot said they have been recorded historically.
Shinbrot has tried to recreate earthquake lights in his lab by simulating “slip events” similar to how tectonic plates slip past one another during an earthquake. He said his lab has measured voltage changes during these slip events, supporting the idea that such voltage changes may occur during an earthquake.
‘A big hug to everyone’: 1 dead after powerful earthquake rocks Mexican resort city
But the debate over why these voltage changes occur is charged, he said. Some believe the light is caused by the friction of the rock releasing energy. Others say some rocks produce significant electric fields when they are compressed in certain ways.
“The cause of these lights is something that’s quite controversial because no one really knows,” Shinbrot said.
The U.S. Geological Survey says there is also debate over whether EQL exist at all, and some geophysicists “doubt that any of the reports constitute solid evidence for EQL, whereas others think that at least some reports plausibly correspond to EQL,” according to the USGS website.
The website also states that some EQL reports actually turned out to be caused by shaking powerlines during earthquakes.
Shinbrot said the lights in Mexico may be earthquake lights but could also be electric shorts or exploding infrastructure like power stations caused by the earthquake.
“The overall message from me is that earthquake lights do appear to exist and are mysterious,” he said. “I don’t know that this particular example is earthquake lights, but it could have been. And I think it would be worth studying more carefully what the cause of these lights is because very few people are actually doing this research.”
This article originally appeared on USA TODAY: Mexico earthquake: Blue lights in night sky kindled #Apocalipsis scare