Strange green and blue flashes were spotted after an 8.1-magnitude earthquake shattered Mexico on September 7 and led to a death of around 60 people. The quake so large it moved the fault up by 10 meters was the strongest that hit the country in 100 years.
Although it is not entirely clear why the unexplained flashes that resemble lightning show up in the sky, there are multiple reports of them appearing before, during or after earthquakes. They are often described as green smears, orbs of light called ball lightning, bluish flames or quick flashes.
Here are some of the explanations for the phenomenon labeled as Earthquake Lights on social networks that do not include UFOs, planes, and birds. Some believe that those lights come after power supplies are hit. According to seismologist Stephen Hicks “earthquake lights have never been proven” and “simpler explanation is small explosions in electric generators and power systems.” This hypothesis is not so probable as people claim reports of the lights appearing for several minutes in different shapes and colors have existed for thousands of years.
Another hypothesis says the cause of the mysterious lights should be looked for in metamorphic rocks as they release ionized oxygen when under stress. These ions can generate localized electric fields and the strongest among them can lead to coronal discharges, which people see as bursts of visible light. Friedemann Freund from NASA’s Ames Research Center says: “The faster we stretch the rocks, the more of these positive-charge carriers are released.”
The third explanation for these earthquake lights is that they are a result of broken chemical bonds through rubbing, crushing or scratching of quartz, which is one of the most common minerals in Earth’s crust. When pressure is applied on quartz, it pushes surface ions out of their position and produces small electric current. Therefore, when faults move and crush rocks, they could create the lights.