|Mysterious flashes of light lit up the sky in Mexico after the country was struck by an 8.1 magnitude earthquake on Friday. Photo: courtesy Independent
The recent Mexico earthquake resulted in videos of blue and green flashes emanating from around Mexico. The flashes appear similar to lightning and could result from massive releases of energy from the ground as a result of an earthquake. Alternatively, it could be due to major electric system explosions. Both are possible, but it's hard to pinpoint which was the cause for the earthquake that just hit Mexico.
We know of lights reported before or after earthquakes in many instances in the past. For example in 1975 the Kalapana earthquake was reported to produce auroras with a white and blue hue. More recently, the phenomenon was caught on camera during the 2007 Peru earthquake. One thing all of these earthquakes have in common is that they're commonly large in magnitude (>5).
Studies have found the generation of lights as a result of earthquakes could be due to the ionization of oxygen to oxygen anions. Once this ionization occurs, the ions can travel through the rocks through small cracks and fissures until they reach the atmosphere forming plasma light.
Some studies have suggested the lights occur when two rocks rub against one another, once the rocks are separated it causes a positive voltage spike, which on a large scale, produce earthquake lights.
In 2001, NASA scientist Friedmann Freud discovered that "if the stress level (between the rocks) is high, there are electronic loads that momentarily transform insulation rock into a semiconductor." Freud added that the electrical loads are not easy to measure, as they "move with impressive speed, as high as 300 meters per second.
In an interview with National Geographic, he stated: "In the past, people often interpreted [earthquake lights] in religious terms, and in modern times they thought of UFOs, although there is a completely rational physical explanation that we are working on."
Interestingly, similar incidents have also occurred in the past. The Kalapana earthquake in 1975 produces auroras with white and blue hue. More recently, the phenomenon was caught on camera during the Peru earthquake in 2007.