Phlegraean Fields register spike in seismic activity.

The Italian government on Thursday announced new measures in light of increased seismic activity in the volcanic Campi Flegrei area near Naples, including plans for a possible mass evacuation.

The Campi Flegrei, or Phlegraean Fields, has registered months of earthquakes including a 4.0-magnitude tremor on Monday and a 4.2-magnitude quake last week, the strongest to hit the area in four decades.

The government has allocated €52 million for the measures which will include structural inspections on buildings in the area, extra resources and staff for local civil protection agencies, and the launch of an awareness campaign in schools.

Italy's civil protection minister Nello Musumeci said the evacuation plan would be finalised within three months, news agency ANSA reports.

Local hospitals are set to carry out evacuation tests in emergency rooms on Friday and Saturday to ensure that staff are prepared for coping with the fallout from stronger earthquakes or volcanic eruptions.

Declared a regional park 20 years ago, the Phlegraean Fields area is a highly seismic zone of supervolcanic calderas, situated about 20 km the west of Naples.

The Campo 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.

Experts believe the recent spike in seismic activity is linked to 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.

There are 15 towns in the Campi Felgrei area, including Agnano and Pozzuoli, with a combined population of more than half a million people living in the so-called 'red zone' most at risk.