Italy on Thursday vowed to rebuild every home destroyed after two powerful earthquakes that forced thousands to flee in terror but "miraculously" did not cause any fatalities.

Two months after tremors in the same area left nearly 300 dead, the twin quakes ripped through a mountainous, sparsely-populated part of central Italy on Wednesday evening.

Despite numerous building collapses, no deaths were reported in the aftermath of the 5.5 and 6.1 magnitude tremors.

"Given the strength of the shocks, the absence of any deaths or serious injuries is miraculous," Interior Minister Angelino Alfano said, while Prime Minister Matteo Renzi headed to the scene to help oversee rescue efforts.

At least 4,000 people will not be able to return to their homes in the immediate term, according to civil protection officials.

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.

More than 200 aftershocks rattled the area through the night and into Thursday after the initial two were felt in Rome, some 175 kilometres (110 miles) away from the epicentres.

Many people spent Wednesday night in their cars, battered by driving rain. The sun came out on Thursday, but the scale of the task will only become clear in days and weeks to come.

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.

"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."

- Freezing temperatures -

Geologist Mario Tozzi told AFP the damage was caused by a new earthquake, rather than, as first thought, aftershocks from the August one.

Tozzi said the twin tremors were consistent with a pattern of seismic "double strikes" in the central Appenines.

Even in Rome, some people took to the streets as a precautionary measure, underlining lingering jitters after the summer disaster.

Wednesday's tremors struck an area just to the north of Amatrice, the mountain town which was partially razed by the August quake and suffered the bulk of the fatalities.

The epicentres were near the village of Visso, located on the edge of the region of Marche close to the border with Umbria.

"Not a single house is usable," whether because they were totally destroyed, suffered cracks or were just rendered unstable, said Visso mayor Giulio Pazzaglini, talking to villagers in a Red Cross reception centre.

The civil protection agency reopened tent camps set up after the August earthquake but officials warned they could only be a temporary solution as winter approaches.

Many mountain villages in the area are located at an altitude of over 600 metres (2,000 feet) and overnight temperatures will soon be falling below freezing.

"You can't imagine spending winter in a tent. We shouldn't even put up camps," Renzi told a meeting of emergency officials in the town of Camerino.

- 'Thank God we're alive' -

Visso's historic centre was taped off on Thursday, 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."

August's disaster caused an estimated four billion euros ($4.5 billion) of damage and some 1,400 people made homeless are still living in temporary accommodation.

The impact of that quake was magnified because it took place at the height of the summer holiday season, when many normally barely-occupied villages were packed with tourists and families returning to ancestral homes.

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