It could be in response to the p-wave, which arrives before the higher-amplitude shear wave.
It takes time for the earthquake to propagate, much slower than the speed of light.
Earthquake lights have been reported minutes, hours, even days before the quake, and also after them. It's not transformers blowing up, although that also happens and can also light up the sky. The light seems to somehow be caused by massive increases or releases of stress in crystalline bedrock, possibly piezoelectrically in quartz, or similar mechanisms.
There was a paper posted here on HBO that claimed some correlation between cosmic waves and seismic activity. At face value correlation was very strong.
One feature was the asynchronicity - one of the variables had to be lagged, I can't remember which one.
Not sure what to make it but possibly related to lights in the sky.
Maybe the quake caused the arching powerlines in the distance before the quake reached the location of the camera?