Something went wrong, please try again later. Invalid email Something went wrong, please try again later. Our free email updates are the best way to get headlines direct to your inbox Something went wrong, please try again later. Our free email updates are the best way to get headlines direct to your inbox Portuguese power chiefs have attributed the widespread power outages to "anomalous oscillations" in very high-voltage lines, a phenomenon known as "induced atmospheric variation". It could take up to a week for the network to fully normalise again. Portugal's grid operator, REN (Rede Eletrica Nacional), has stated that interruptions to its own power supply were due to a "fault in the Spanish electricity grid". Spain has yet to respond to this claim. Earlier, it was suggested by the head of Spain's electricity network that restoring power could take between six and 10 hours. REN further explained that "due to extreme temperature variations in the interior or Spain, there were anomalous oscillations in the very high voltage lines (400 KV), a phenomenon known as 'induced atmospheric vibration'". "These oscillations caused synchronisation failures between the electrical systems, leading to successive disturbances across the interconnected European network.", reports the Express.