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

The countries’ top officials were trying to determine the cause of an outage that left tens of millions of people across the Iberian Peninsula without power.

Although the incident caused chaos across the region with public transport coming to a standstill, businesses closed and flights cancelled, most research centres were able to secure scientific data and equipment.