During the Loma Prieta quake I heard about it on the radio (I was driving) before it arrived .... light from electrical discharges is always going to arrive bef

During the Loma Prieta quake I heard about it on the radio (I was driving) before it arrived .... light from electrical discharges is always going to arrive before the shockwave so the 'before' part is not at all surprising. The cause of course could easily be from the electricity distribution infrastructure, or from some piezo/etc effect from the earth moving - it's likely not presaging the quake itself