Electricity is pulsing through Spain and Portugal again after a massive outage knocked out power in both countries on Monday. So too are questions.

Even as electricity was restored across Spain and Portugal after a daylong blackout, residents tried to make sense of 18 hours of the “insanity.”

Spain and Portugal switched their power back on after the worst blackout in their history, though authorities offered little explanation for what had caused it or how they would prevent it happening again.