I live in a country that follows the UK mains specification, where there are 3 pins on a wall outlet with the topmost pin being earth/ground. Now, is it possible that during a lightning strike, extra voltage from the lightning travels up the earth or ground wire to the mains outlet and to any equipment connected to the mains?
I am asking because, during numerous occasions, with my desktop computer plugged in (not switched on), during a severe lightning strike, I can hear and see a spark somewhere on the casing of the computer, although no damage is suffered. I am wondering might this be the result of lightning voltage travelling upwards through the earth / ground wire to my computer thus causing this phenomenon? Or are there any other explanations such as extra electromagnetic effect during a strike, etc.?