[winoneforthegipper]

Good point(s)!

[The Cajun]

Another silly thought, lots of quartz underground, start applying mechanical stress to quartz and up jumps electrical energy.
Another thing about quartz, if you apply electrical energy to it, it deforms slightly.
Wonder if a cascade thing could cause a run away condition, deform due to pressure and shifting, electrical energy, more deforming, more electrical energy, etc, etc.
Could be a combination of sources for the electrical discharges manifesting themselves in different, but observable ways, if we really look.