I only recently became familiar with a phenomena called "earthquake lights," a type of luminous phenomena that appears in the sky prior to some earthquakes. The lights are usually blue or white flashes of light, but may also include a wider color spectrum.
Here is a picture of what is alleged to be earthquake lights that occurred prior to the 2008 Sichuan Earthquake.
When I first read about earthquake lights the other day, it was in an article blaming them on a HAARP conspiracy. According to the article I read, earthquake lights had been seen prior to the earthquakes in Haiti and Chile. I decided to see what else I could find out about earthquake lights, and I came across a question regarding earthquake lights on the FAQ page for the U.S. Geological Survey. According to the answer for that question, earthquake lights have been reported since ancient times but were not acknowledged in the seismological community until the 1960s. There are several theories as to what may cause the earthquake lights, but there is no single theory that has been agreed upon.
Considering earthquake lights have been reported since ancient times, all the occurrences can't be blamed on HAARP since HAARP wasn't established until 1993. Whether or not any of the recent occurrences can be blamed on HAARP, I don't know. Whatever the lights are, they appear to be some sort of natural occurrence.
It's not that I'm surprised that mysterious lights have been known to appear in the sky before an earthquake, but I am a little surprised that I haven't heard about it before. It's possible I may have heard about it in the past, but if I did, I had forgotten about it. So the question in my mind is why aren't these lights more widely publicized? When I was a kid in school, we were taught that tornadoes sound like trains. So I knew to associate a tornado with the sound of a train. But I don't recall anyone ever mentioning that rainbow colored lights sometimes appear in the sky prior to earthquakes. It may still be difficult to accurately predict an earthquake even if earthquake lights appear because they can appear as much as a few weeks in advance or even after the actual earthquake, and the lights may appear far away from the epicenter too. But you'd think it would be a good idea to tell people that if they see mysterious rainbow colored lights appearing in the sky on an otherwise clear day, they may want to start securing anything fragile -- you know, just in case.