According to a recent report by INGV Naples, the ground deformation of the Campi Flegrei (Phlegraean Fields) near Naples has increased considerably lately.
During the last 12 months, the ground in some places near the town of Pozzuoli was uplifted by about 8 cm.
The largest uplift, recorded by GPS devices, occurred during the months of July-August 2012 and since December. The trend appears to be continuing at the moment.
Such (sometimes dramatic, totaling up to several meters in a few years) ground uplift and subsidence have been known in the Phlegraean Fields since antiquity and are not a new phenomenon. They can usually be explained by normal pressure, temperature and density variations of the giant hydrothermal system of the Campi Flegrei caldera and may not necessarily indicate an imminent eruption.
However, in addition to the detected ground deformation, scientists also measured increased numbers of micro earthquakes, a rise in temperature and in particular, an increase in the proportion of the gases of magmatic origin at fumaroles in the Solfatara crater.
As the hydrothermal system is closely connected with the underlying complex magma chamber of the Phlegrean Fields, new magma movements could in fact be the culprit for the observed changes. Whether these, and if so when, will lead to a new volcanic eruption is currently uncertain.
A much larger increase of such observed changes should probably be expected if in fact should new volcanic activity was to announce itself. The last volcanic eruption occurred after a rest period of about 3000 years in the year 1538 AD and built a new cinder cone, the Monte Nuovo ("New Mountain") near Pozzuoli.
Strong ground uplift, earthquakes and changes in springs and fumaroles preceded the eruption according to historical sources. Even though it was - geologically speaking - a rather small eruption, the effects of a similar event today would be devastating for the very densely populated area. It should be hoped that the residents and all involved are spared such a scenario, at least for the near future.