Unusual cause of massive blackout in Spain and Portugal revealed

The power outage that hit Portugal was caused by a fault in the Spanish electricity grid, linked to a "rare atmospheric phenomenon", according to what Portugal's "REN" reports.

REN is the main energy company in Portugal, responsible for the management and development of the country's two main energy networks, the national electricity transmission network and the national natural gas transmission network.

REN states that extreme temperature changes in Spain have caused "anomalous oscillations" in very high voltage lines.

They say this is known as "induced atmospheric change", which in turn led to oscillations that caused synchronization failures between systems. This led to successive outages in the interconnected European grid, they added.

They also state that, given the complexity of the problem, it could take up to a week for the network to fully return to normal.

The director of Spain's electricity grid said it could take hours to restore power.

At a press conference, Red Electric CEO Eduardo Prieto told reporters that resolving the problem could take "between six and ten hours."