I didn’t know this light phenomenon and haven’t heard about it until today, but it seem’s not to be completely uncommon.
„An earthquake light is an unusual luminous aerial phenomenon that reportedly appears in the sky at or near areas of tectonic stress, seismic activity, or volcanic eruptions. Once commonly challenged, it was not until photographs were taken during the Matsushiro earthquake swarm in Nagano, Japan, from 1965 through 1967, that the seismology community acknowledged their occurrence.“ http://en.wikipedia.org/wiki/Earthquake_light
YouTube Video -30 mins before the 2008 Sichuan earthquake in China