When the devastating 8.1 magnitude earthquake shook Mexico, it brought with it a strange side effect: earthquake lights.
Photo of earthquake lights over Mexico by Twitter user @lalocedeno
Just before midnight on September 7, powerful tremors shook Mexico as well as Guatemala. Tens of millions of people felt the tremors, and both countries suffered casualties. Reports say that at least one person died in Guatemala, while the death toll in Mexico currently stands at 90.
As if a huge earthquake wasn't enough, eerie blue and green flashes of light also appeared in the skies over Mexico. An earthquake of this magnitude can already make it seem like the end of times is nigh, and unexplained lights certainly didn't make things better. Fortunately, however, these aren't the signs of an impending apocalypse. There's a scientific explanation that should settle fears of the world's end.
Scientists say that certain kinds of rock can cause these lights to appear during an earthquake. But how can something that occurs deep in the earth affect the skies?
Earthquake lights aren't a new phenomenon. There have been numerous reports of the appearance of these lights accompanying a big earthquake. The Kalapana earthquake of 1975 reportedly produced blue and white auroras. The 2007 Peru earthquake as well as the 1930 earthquake in Japan produced the same lights as well. It seems that earthquakes with a magnitude of 5 or stronger are capable of producing these lights.
For a long time, however, people thought that these lights aren't, in a nutshell, real. Finally, researchers produced a study in 2014 pointing out that there have been numerous but similar reports of these lights from all over the world. The lights over Mexico resembled flashes of lighting. However, according to the aforementioned 2014 study, flashes aren't the only kinds of lights that we can expect with a magnitude 5 earthquake or stronger. The lights can also come in the form of orbs or bluish flames.
There have been theories that attempt to explain what's causing these lights. According to this 1998 study, the movement of quartz-bearing rocks may cause a strong pizoelectric field that can in turn cause flashes of lights. Another similar study from 2010 says that the stress on the Earth's crust may release electric fields that can charge molecules in the air.
Soldiers in Juchitan clear debris from a house destroyed in the earthquake [Photo by Reuters]
In yet another study, researchers simulated an earthquake in a lab. They found that the movement of the earth during a quake may cause voltage spikes, which leads to the appearance of the lights.
Thus, there's no definitive answer yet as to what causes the strange lights. What we do know now, however, is that this recent earthquake is the most powerful one to hit Mexico in decades. It was so strong that its aftershocks registered at a magnitude of 5 or stronger. We may not know what causes earthquake lights, but they serve as a reminder of the incredible amount of energy that earthquakes release.
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