...several times, in Florida. Note the spectral color distribution in the cloud, from purple to red, just like a rainbow. If you are in the habit of wearing Polaroid sunglasses when outdoors, as I am, you will see it much more frequently. For some reason, at certain polarization angles, the effect is much more pronounced. The rainbow light dispersion is caused by differential refraction, probably by ice crystals at high altitudes. I've even seen these at night, in bright moonlight.

I can't rule out it was somehow caused by the earthquake, although it is probably not related. Florida has no seismic activity that I know of. I have to admit, though, unless the camera somehow enhanced this display, I've never seen it quite as vivid and colorful as this before.