Earthquake Light and Earthquake Clouds

Earthquake Light and Earthquake Clouds

"Earthquake lights" and "earthquake clouds" are an excellent example of something that almost everyone thought was crackpot bunk, until enough photographs and first-hand experiences were accumulated by enough reputable people that it was finally acknowledged as a real thing by science. In the case of earthquake lights, it was the "earthquake swarm" that hit Nagano, Japan in 1965-1967 that did the trick.
Earthquake lights have been seen before, during, and after earthquakes. They don't usually last very long - typically between a few seconds and a few minutes. They often occur high in the air, which makes them visible from far away, depending on the terrain.
They are usually seen as a glow or shimmer in the air. Some instances of earthquake lights have been described as resembling the aurora borealis. Others look like a rainbow, sun dog, or just a luminescent glow in mid-air.
In our modern world where everyone is apparently carrying a video camera at all times, earthquake lights have been well documented in both photographs and video. Here is some video of earthquake lights observed half an hour before the 2008 Sichuan earthquake hit China.
The mechanism behind earthquake light is unknown. People speculate that it could be the result of piezoelectricity from tectonic plates crushing or rubbing against large quartz deposits. Others, that the impending earthquake disrupts the local magnetic field, causing a sort of earthbound aurora. Needless to say, this phenomenon has been somewhat difficult to either study in the field or reproduce in the lab!
Earthquake clouds have been known to humanity for centuries. According to this website, "ancient Chinese and Italians were aware of unique clouds that gave sign preceding large earthquakes." Science seems willing to accept that large earthquakes could be preceded by unusual cloud formations, but skeptical of those who claim to be able to predict earthquakes based on cloud formations they see days or even weeks before the earthquake occurs.
These clouds have often been accompanied by a temperature increase along the fault line. Understandable, given the magnitude of the forces that gather behind an earthquake. And understandable as well that the heat might disrupt cloud formation. As to whether earthquakes disrupt the local magnetic field, this has (like earthquake light) proven to be difficult to measure.
One problem with putting too much belief in phenomena like these is the risk of confirmation bias. After a big earthquake, it's natural to remember back to anything unusual that occurred, and then draw a conclusion based on a faulty cause and effect.