POZZUOLI - Authorities evacuated 39 families near the Italian city of Naples and schools were closed on Tuesday after a wave of tremors of a strength not seen for decades sparked panic but no injuries.
One 4.4-magnitude quake was registered shortly after 8pm on Monday evening at a depth of 2.5 kilometres, according to the National Institute of Geophysics and Volcanology (INGV).
It was part of what the institute called a "seismic swarm" overnight in which some 150 quakes were recorded.
The institute's Mauro Di Vito said: "This is the most powerful seismic swarm in the last 40 years."
Many residents of Pozzuoli, a city near Naples, rushed out of their homes into the street following the tremors, which caused some damage to buildings but no casualties.
Italy's Civil Protection Department said on Tuesday morning that 39 families had been evacuated from 13 buildings following the outcome of inspections.
The mayor of Pozzuoli, Gigi Manzoni, urged people to remain calm but acknowledged it was a situation that was "stressing us all".
Four reception centres were set up overnight for people who did not feel safe in their homes, while authorities in Naples arranged to send 400 temporary beds to the area.
Schools were closed on Tuesday for inspections.
Pozzuoli is on the Campi Flegrei (Phlegraean Fields), Europe's largest active caldera -- the hollow left after an eruption.
Residents are used to the tremors but many of the 500,000 inhabitants living in the danger zone were already spooked by a 4.2-magnitude quake last September.
Emergency services reported cracks and pieces falling from buildings after Monday's quakes.