Power Is Restored in Spain and Portugal After Widespread Outage

The traffic lights flashed from red to green again. The subways were running in Madrid and Lisbon. And waiters were serving food and generous pours of beer and wine to patrons on restaurant terraces along quieter-than-normal streets.

A day after Spain and Portugal were hit by extensive blackouts, electricity had returned to most areas of both countries on Tuesday, leaving many relieved but also sharply critical about what exactly had caused the power failure.

Prime Minister Pedro Sánchez of Spain said his country had recovered more than 95 percent of the total supply by 6.30 a.m. Tuesday. In Portugal, a spokesperson for the electricity and gas supplier REN said that power had been restored to all the substations of the country’s grid and that everything was “100 percent operational.”

But the cause of the blackout, which stranded tens of millions of people on the Iberian Peninsula, remained unknown.

Eduardo Prieto, director of services for Spain’s national power company, Red Eléctrica, said that there were no “definitive conclusions” about the reasons for the outage.

He joined a chorus of officials who declared that there had been no cybersecurity attack. But he also ruled out human error and meteorological causes.

The Spanish electricity system had shut down after being hit by two separate power outages, a second and a half apart, he said.

“This may seem like a small amount,” he said, “but in the electrical world, it’s a significant amount.” The shutdowns had occurred in southwestern Spain, he added.

Mr. Sánchez said that his government’s second priority, after ensuring that power had been fully restored, was to analyze what had caused the shutdown — both through a technical analysis committee at the national level and through the European Commission.

“Citizens must be clear that the Spanish government will get to the bottom of this matter and implement the necessary measures to ensure this never happens again, and we will hold private operators accountable,” Mr. Sánchez said on Tuesday. He said he expected answers within “hours or days.”

A judge with the Spanish National Court ordered reports to be submitted to him within 10 days — including one from the police headquarters and another from the national intelligence department in charge of cyberattacks.

Portugal’s prime minister, Luís Montenegro, said that a seven-member independent technical committee would assess the management of the crisis, including government communications, and the resilience of the country’s electricity system and infrastructure.

“We need responses that are as quick as they are urgent,” said Mr. Montenegro, who is heading into an election on May 18, and was supposed to be debating the opposition leader, Pedro Nuno Santos, on Monday evening, when the power was still out. That debate was rescheduled for Wednesday evening.

Kristian Ruby, secretary general of Eurelectric, a trade body that represents the European electricity industry, said that it could take months to complete the technical analysis.

But some initial information has already emerged, he said. Around noon on Monday, a high-voltage connection between France and Spain was interrupted. The power outage occurred just over 30 minutes later.

While that interruption would have been disruptive, it would not normally lead to a “system collapse” like that seen on Monday, Mr. Ruby said. Something more would typically need to happen, “like a sudden outage at a power plant, a sudden development on the demand side,” he said. “Then you can have an incident like this.”

Mr. Ruby called the outages “somewhere on the scale between a 50- to 100-year event.”

Both Spain and Portugal shut down on Monday afternoon. Traffic lights went dark, trains and subways halted, elevators stopped — many with people stuck inside.

Businesses, factories and schools shut down, and airports delayed and canceled flights.

There were also problems connecting to the internet and to phone networks, leaving many bewildered and unable to obtain information.

Joe Meert, a geology professor at the University of Florida, said that he and his wife Michelle were among 35,000 passengers stranded on trains across Spain on Monday afternoon.

They had been traveling from Madrid to Valencia as part of their 30th anniversary celebration trip. Instead, they spent more than 11 hours looking at farm fields just outside of Madrid in the dimming light and then the dark, he said.

Finally, around midnight, the Meerts were directed to climb onto another train and then slowly towed by a diesel engine back to the Atocha station in Madrid. There, Red Cross workers and soldiers distributed blankets to crowds of arriving travelers throughout the night.

“It was packed. People were lying down everywhere,” Mr. Meert, 67, said. In the morning, the couple was able to catch another train to restart the journey.

When the lights suddenly turned back on Monday evening, cheers erupted across Madrid.

In cities across Spain and Portugal, life was returning in spurts on Tuesday. While subways were back up in Madrid and Lisbon, Spain’s national railway system reported that many of its commuter trains had reduced service or were canceled.

The Spanish transport ministry reported that all airports were operating. In Portugal, the infrastructure minister, Miguel Pinto Luz, announced that it would take “two or three days” for flights to return to normal at Lisbon’s international airport.

“Yesterday, there were practically no flights, and they were backed up with today’s flights,” Mr. Pinto Luz told the news channel Now.

Mobile phone and fiber optic service were working again. The Madrid Open, an international tennis tournament, was back up and running on Tuesday after the outage forced the cancellation of 22 matches on Monday. Schools were opened across both countries, though some with low attendance.

“It seems like everything is better today, but I don’t understand how something like this is possible with all the technology we have today,” said Doroteo García, an 87-year-old retiree, walking with difficulty near a Madrid’s still crowded Atocha train station. He had spent the day before trapped in his apartment, he added, because the elevator was not working.

“I lived off canned sardines all day because I couldn’t cook,” he said.

In central Lisbon, parks were full of runners and stretchers Tuesday afternoon and grocery stores, which had shut down during the brief crisis, were back to business.

At Rodas Restaurant, tables were set for the lunch rush. The manager, Hugo Carvalho, said that the restaurant had not suffered any big losses from the electricity cut.

He noted that the restaurant closed at 6 p.m. during the blackout and that the only thing he had to worry about was the ice cream in the freezer.

“We ate most of that,” said Mr. Carvalho, smiling.

Azam Ahmed contributed reporting from Lisbon; Tiago Carrasco from Peniche, Spain; Jonathan Wolfe from Murcia, Spain; and John Yoon from Seoul.