Earthquake light spotted over China before actual tremors

I’ve never heard of this natural phenomenon before, but apparently earthquake lights sometimes occur directly above or near the epicenter of an earthquake before the earthquake actually starts. [via]

In some ways, I suppose this is sort of like how the waters at a beach recede prior to a tsunami. It’s a strange event that scientists have no yet been able to understand fully. I know Wikipedia isn’t the best source for this, but here are some theories that have been collected:

One theory suggests that earthquake lights are a form of plasma discharge caused by the release of gases from within the Earth and are electrically charged in the air.

Another possible explanation is local disruption of the Earth’s magnetic field and/or ionosphere in the region of tectonic stress, resulting in the observed glow effects either from ionospheric radiative recombination at lower altitudes and greater atmospheric pressure or as aurora. However, the effect is clearly not pronounced or notably observed at all earthquake events and is yet to be directly experimentally verified.[citation needed]

Another explanation involves intense electric fields created piezoelectrically by tectonic movements of rocks containing quartz.

Earthquake clouds are a similar natural phenomenon.

Here’s one more video.