STRONG aftershocks have sent a fresh wave of fear across earthquake-shattered central region as rescue crews pulled a young woman alive from a collapsed building about 42 hours after the main quake.

Eleonora Calesini, a 20-year-old student, was found alive in the ruins of the five-story building in central L'Aquila, said her grandfather, Renato Calesini, in the seaside town of Mondaini.

"She's safe!" he said, adding that her father had gone to the devastated city in the Apennine mountains to try to locate the student, who wears a hearing aid. She reportedly had an arm injury but was in good condition otherwise.

The death toll from Italy's worst earthquake in three decades has climbed to 235, with 15 still missing, civil protection officials said.

The dead included four students trapped in the rubble of a dormitory of the University of L'Aquila.

Rescue crews gave up gingerly removing debris by hand and brought in huge pincers that pulled off parts of the dorm roof, balconies and walls, showering debris down.

"Unless there is a miracle, I've been told that they probably are dead," university rector Ferdinando Di Orio said.

The strong aftershock rained debris on screaming residents and rescue crews, who ran from the site.

"I want to go home!" screamed a woman after chunks of facade rained down from a badly cracked building.