Campi Flegrei rocked by series of tremors since Sunday afternoon.Italy's Campi Flegrei, a highly seismic zone near Naples, was shaken by a 4.0-magnitude earthquake early on Monday, two months after the area was hit by the strongest tremor in 40 years.The earthquake occurred at 04.55 at a shallow depth of around 0.3 kilometres near Pozzuoli, Italy’s National Institute of Geophysics and Volcanology (INGV) said in a statement. The quake was the strongest in a series of tremors that began in the Campi Flegrei area on Sunday afternoon, with two 3.3-magnitude earthquakes registered in Pozzuoli at 16.10 and 16.36. Italy launches new earthquake early warning system for Rome-Naples trains At least 14 minor tremors were recorded in the area since midnight, including two 2.8-magnitude tremors at 12.33 and 01.29, with an epicentre near Pozzuoli.  Authorities were carrying out checks on Monday morning but there were no immediate reports of injuries or damage. Bradyseism Experts say the recent spike in seismic activity in the Campi Flegrei area is the result of bradyseism, a phenomenon that involves the gradual uplift or descent of part of the earth's surface, caused by the filling or emptying of underground magma chambers or hydrothermal activity. "These [seismic] events are perfectly consistent with the ongoing bradyseismic crisis" - Mauro Antonio Di Vito, outgoing director of the INGV Vesuvius Observatory, said last week - "In this area, the gradual uplift of the ground continues at a rate of 1.5 centimetres per month, stressing the rocks, which fracture and cause earthquakes." Earlier this year the Campi Flegrei area was hit by two strong earthquakes, including one of 3.9 magnitude in February and one of 4.4 magnitude in May, before experiencing a 4.6 magnitude earthquake on 30 June, the strongest in the area in 40 years. Campi Flegrei Declared a regional park 20 years ago, the Campi Flegrei area is a highly seismic zone of supervolcanic calderas, situated to the west of Naples and about 50 kilometres from Mount Vesuvius. The Campi Flegrei volcano last erupted in 1538 however earthquakes have been common in the area since 1950, with a surge of seismic unrest in the early 1980s. There are 15 towns in the Campi Felgrei area, with a combined population of more than half a million people living in the so-called 'red zone' most at risk. Last year the Italian government announced new measures in light of the increased seismic activity in the area, updating emergency plans for a possible mass evacuation.

Italy's Campi Flegrei, a highly seismic zone near , was shaken by a 4.0-magnitude earthquake early on Monday, two months after the area was hit by the . The earthquake occurred at 04.55 at a shallow depth of around 0.3 kilometres near Pozzuoli, Italy’s National Institute of Geophysics and Volcanology (INGV) said . The quake was the strongest in a series of tremors that began in the Campi Flegrei area on Sunday afternoon, with two 3.3-magnitude earthquakes registered in Pozzuoli at 16.10 and 16.36. At least 14 minor tremors were recorded in the area since midnight, including two 2.8-magnitude tremors at 12.33 and 01.29, with an epicentre near Pozzuoli.  Authorities were carrying out checks on Monday morning but there were no immediate reports of injuries or damage. Bradyseism Experts say the recent spike in seismic activity in the Campi Flegrei area is the result of bradyseism, a phenomenon that involves the gradual uplift or descent of part of the earth's surface, caused by the filling or emptying of underground magma chambers or hydrothermal activity. "These [seismic] events are perfectly consistent with the ongoing bradyseismic crisis" - Mauro Antonio Di Vito, outgoing director of the INGV Vesuvius Observatory, said last week - "In this area, the gradual uplift of the ground continues at a rate of 1.5 centimetres per month, stressing the rocks, which fracture and cause earthquakes." Earlier this year the Campi Flegrei area was hit by two strong earthquakes, including one of  in February and one of  in May, before experiencing a on 30 June, the strongest in the area in 40 years. Campi Flegrei Declared a regional park 20 years ago, the Campi Flegrei area is a highly seismic zone of supervolcanic calderas, situated to the west of Naples and about 50 kilometres from . The Campi Flegrei volcano last erupted in 1538 however earthquakes have been common in the area since 1950, with a surge of seismic unrest in the early 1980s. There are 15 towns in the Campi Felgrei area, with a combined population of more than half a million people living in the so-called 'red zone' most at risk. Last year the Italian government announced new measures in light of the increased seismic activity in the area, updating emergency plans for a possible .