Italy is very geologically alive , with many volcano – some of which have beendeadly . However , the largest one does n’t look like your median volcano at all : Campi Flegrei looks like a depression . It is a caldera with a diameter between 12 to 14 kilometers ( 7.5 - 8.7 miles ) , and part of it is in the sea . It is a supervolcano , and fresh models paint a picture that its freshness might be acquire penny-pinching to rupture , with a chance of a future eruption .

Campi Flegreihsn’t had an extravasation since 1538 , but over the last 70 years it has been quite restless . In the 50 , 70s , and 80s it had two - year spikes of activity , and over the last 10 , there has been a slow but unfluctuating uptick in action . The coastal town of Pozzuoli near the centre of the caldera has been repeal by almost 4 meter ( 13 feet ) , a phenomenon known as bradyseism . In April alone , 600 earthquakes were immortalise , the high monthly number on disk .

For six years , scientists have employed a model to describe the conduct of Campi Flegrei , both its seism and the uplifting . The supervolcano has been do as the model has auspicate . According to this , part of the volcano ’s crust had been load nearly to breaking point . This suggests that a severance is likely in the inadequate term .

" Our new study confirms that Campi Flegrei is moving nigher to bust . However , this does not entail an eruption is guarantee . The falling out may open a crack through the insolence , but the magma still require to be pushing up at the correct location for an eruption to occur , " lead author Professor Christopher Kilburn , UCL Earth Sciences , say in astatement . " This is the first clip we have applied our model , which is found on the physical science of how rocks split , in existent - time to any vent . "

The earthquakes indicate mounting pressure from below . The formula of earthquake suggests that the cheekiness is not responding in an flexible elbow room ; or else of stretching and turn , it ’s fracture . These are not the solid quakes the surface area has experienced in the last several decades , but the cheekiness is now weaker . The tensile strength – the maximum stress a material can bear – of the crust today is about one - third of what it was in 1984 .

" Our termination show that part of the volcano are becoming weaker . This signify that it might break even though the tenseness pulling it apart are small than they were during the last crisis 40 eld ago , " add together Dr Nicola Alessandro Pino from the Vesuvius Observatory , which represents the Istituto Nationale di Geofisica east Vulcanologia ( INGV ) in Naples .

The irruption of 1538 occupy place over 8 sidereal day from Monday , September 30 . It started with the searecedingand a significant uplift of the ground greater than had been experienced in the past few decades two days before the eruption . Monte Nuovo , the volcanic lamp chimney from which the eruption adopt place , was fully formed by October 2 . Monte Novo is one of 24 volcanic crater and volcanic edifices in the supervolcano . Most of them are underwater .

While the model is intriguing , there is a lot we do not know about what is going on . It is very significant to find out as much as possible – presently , 360,000 people live on the supervolcano ’s roof . Monitoring its movements and moulding possibility is crucial to their safety machine .

" We can not see what is happening underground . alternatively we have to trace the clues the volcano gives us , such as earthquakes and uplift of the ground , " Dr Stefania Danesi from INGV Bologna explain .

The work is published in the journalCommunications Earth & Environment .