Despite numerous building collapses, no deaths had been reported by midday, more than 17 hours after the first of the 5.5 and 6.1 magnitude tremors.
Italian Prime Minister Matteo Renzi visited some of the affected towns on Thursday afternoon and promised that the government would do its utmost to help them make a full recovery, starting with the approval of an emergency decree allocating relief funds.
The government announced the release of 40 million euros ($44 million) and extended a state of emergency declared after the deadly August quake.
"We will rebuild everything, 100 percent, that is the government's commitment," said Vasco Errani, the reconstruction supremo appointed after the August disaster.
"Given the strength of the shocks the absence of any deaths or serious injuries, which we hope will be confirmed, is miraculous," Interior Minister Angelino Alfano said.
The national civil protection agency described the damage as "very significant" but said that although two elderly women had already been rescued from rubble, they were not aware of anyone else believed to be missing or trapped. Facebook once again activated its 'Safety Check' feature.
After a night of heavy rain, rescue workers were trying to assess the full extent of the latest disaster in central Italy, which toppled buildings and injured dozens.
Meanwhile, hundreds of people were unsure where they'd be living for the forseeable future, their homes either uninhabitable or completely destroyed.
More than 250 aftershocks rattled the area through the night after the initial two were felt in Rome, some 175km (110 miles) away from the epicentres. Three of the aftershocks measured above 4.0 on the Richter scale.
Marco Rinaldi, mayor of the village of Ussita, described "apocalyptic" scenes.
"People were in the streets screaming. Many houses have collapsed. Our town is finished," he said.
"The second quake was a long, terrible one."
Photo: Tiziana Fabi/AFP
One man was reported to have died of a heart attack, and dozens of people were injured, the authorities said.
The tremors struck an area northeast of the capital Rome near Amatrice, the town flattened by a 6.0-6.2 quake which killed almost 300 people and injured hundreds more in August.
The first quake Wednesday sent people out of their residences, likely saving lives when the second, more destructive, 6.1 magnitude one struck two hours later.
In both cases the epicentre was near the village of Visso in the central Marche region.
"I've felt a lot of earthquakes but that was the strongest I've ever felt. Fortunately everyone had already left their homes after the first quake so I don't think anyone was hurt," Rinaldi said.
"The town has been brought to its knees, and Ussita lives off tourism," commented the concerned mayor.
Several dozen people were treated for light injuries or shock, civil protection chief Fabrizio Curcio told a news conference, however no one was reported missing or dead as a result of the collapses.
"Ultimately, the situation is not as catastrophic as might have been expected" given the strength of the tremors, he said.
The quakes were felt in the capital Rome, rattling windows and doors. The foreign ministry was temporarily evacuated and residents ran into the streets, underlining lingering jitters after the summer's disaster.
The second was felt as far away as Venice in the far north, and Naples, south of the capital.
The epicentres were near the village of Visso, located on the edge of the region of Marche close to the border with Umbria. Visso is just 70 kilometres (45 miles) from Amatrice and also not far from L'Aquila where a powerful earthquake killed more than 300 in 2009.
Across the region, hospitals, a university residence, a retirement home and even a prison had to be evacuated. Schools were closed on Thursday to allow structutral safety checks to be carried out.
"Tonight we're going to go. But tomorrow I don't know. The tents, I can't go there, it's too cold," a resident of Visso said on television.
For people who are unable to return home immediately, civil protection has arranged accommodation in gyms and prepared to reopen some of the tent camps which were set up after the August earthquake.
The Civil Protection Agency in the Marche said they feared that between 2,000 and 3,000 people had been displaced by the quake, and that many of the homes which had survived the August disaster would now be uninhabitable.
"I want to thank those working in the rain in the earthquake zones. All of Italy is wrapping its arms around the communities that have been hit once again," Prime Minister Matteo Renzi tweeted.
Voglio ringraziare chi sta lavorando sotto l'acqua nelle aree del #terremoto. Tutta l'Italia abbraccia forte le popolazioni colpite ancora.— Matteo Renzi (@matteorenzi) October 26, 2016
A Serie A football match between Pescara and Atalanta was halted for several minutes when the first tremor hit.
Concerns were also raised over damage to the region's cultural heritage; several medieval churches were destroyed, as well as museums. Early manuscripts by poet Leopardi were moved to Bologna from Visso.
'Like bombs falling'
The mayor of Serravalle del Chienti, Gabriele Santamarianova, said the quake felt "like bombs were falling".
"We saw a cloud of dust, we don't yet know what has fallen down. We'll see once the sun comes up."
The little town of some 300 people is near Arquata del Tronto, one of the areas worst hit in the August 24th earthquake.
In Ascoli, another town hit hard in August, the mayor said spooked residents were fleeing by car.
Visso's mayor Giuliano Pazzaglini said two thirds of the buildings in his village had been left unusable.
Photo: Tiziana Fabi/AFP
Its historic centre was taped off on Thursday morning, barring pensioner Massimo Testa from going back to what remains of the 15th Century house he and his wife had lovingly renovated.
"We only just had enough time to get out after the second shock before the house collapsed," he told AFP with tears in his eyes.
"My wife was petrified, she could see masonry falling around her. Thank God we are still alive, that is the most important thing."
Bulldozers were working to clear one of the village's main access roads, which was blocked by the collapsed facade of a building. The village church was partially destroyed, its belltower still standing but bearing large fissures.
August's disaster caused an estimated four billion euros ($4.5 billion) of damage, with 1,400 people still living in temporary accommodation.
Around two-thirds of the deaths occurred in Amatrice, a popular tourist destination packed with holiday-makers when the quake struck at the height of the summer season.
Further damage was caused to Amatrice by Wednesday's quake, including the collapse of its city hall, and the 'palazzo rosso', a four-storey red brick building in the centre of the town, which had withstood August's earthquake. The video below, shared by the Italian fire service, shows the rubble of the building.