The surreal Solfatara Crater, arguably the best known volcanic vent in the Campi Flegrei (Phlegrean Fields), represents the most compelling evidence of the deadly heat that lies underneath the surface. On September 12, 2017, that very heat caused one of the most harrowing tragedies ever brought about by volcanic activity.
Three Italian family members were killed after a 11-year old kid climbed over a fence that keeps people off the most dangerous area and fell into a 3-m deep sinkhole. Both his parents tried to rescue him and fell into the sinkhole as well. They did not make it to the surface.
This was the first time that people were killed at the Campi Flegrei after nearly 500 years: In 1538, following decades of progressive uplift of the ground due to the rising magma underneath, a moderately explosive eruption caused the formation of the Monte Nuovo, in a week’s time. On the last day of the eruption, 24 people climbed the newly-formed cone, and were suddenly blown away by an explosion.
Already back in Roman times, the Campi Flegrei were known to be the “gates of hell”. Galileo Galilei, one of the greatest scientists of all time, in 1588 stated that the Dark Forest narrated by Dante Alighieri corresponded to the woods that surround Lake Averno, another volcanic crater formed in the Phlegrean Fields 4,000 years ago.
What are the Campi Flegrei? They are a typical kind of “supervolcano“, represented by a huge caldera (with a diameter of about 15 km), the formation of which was most likely due to the eruption of the Campanian Ignimbrite (39,000 years ago).
Within the caldera, over the last 12,000 years several eruptions have occurred, giving rise to a large number of monogenic volcanoes, that is volcanic centres that are formed during one single eruptive phase, such as the Monte Nuovo. The almost 500,000 inhabitants of the Phlegrean area, west of Naples, are aware of the volcanic risk, attested by the numerous and recent bradyseismic episodes (1982-1984) and by the several fumaroles and thermal springs scattered all across the Fields.
Bradyseism is a phenomenon that is common in many calderas around the world, but that is especially intense at Pozzuoli, a city within the Campi Flegrei that has been subject to repeated ground uplift and downlift episodes, known since Roman times and caused by the push of the underlying magma chamber, a huge reservoir of molten material that is able to feed cataclismatic eruptions such as the one that ravaged southern Italy 39,000 years ago.
Scientists believe the latest major eruption in the area may have led to a “volcanic winter” much similar to the one triggered by Tambora Volcano when it erupted in 1815. On the Volcano Explosivity Index, a scale that ranks the power and destructive potential of eruptions, both the eruption of the Campanian Ignimbrite and the one from Mount Tambora in 1815 rank a 7 out of 8.
As a consequernce of the latest mammoth eruption at this caldera, in Eastern Europe temperatures fell by 3 degrees Celsius. The most intense cooling, of up to 6 degrees C, was centered over Asia and North America.
Some researchers have argued that the chilling months following the blast could have pushed the already suffering population of Neanderthals in Europe to extinction.
In recent years, scientists have observed ominous changes in the Campi Felgrei: This prompted Italian authorities to raise the alert level in the area from green to yellow in 2012, meaning the area needs scientific monitoring. Ground deformations currently indicate that magma has risen to shallower levels in the crust (about 3.5 km from the surface) and this might have the effect of weakening the rock cover that separate the magma chamber from the surface.
The major, Eruptive Precursors Project, is a current effort aimed at understanding if and when the Campi Flegrei are likely to cross a critical threshold possibly leading to an eruption. If that would be the case in the next few years, 3,000,000 people in the Naples area will have to be evacuated, and the global population will have to brace for the environmental and climatic consequences of what might be a gigantic eruption, one that has never been witnessed by man in historical times.
Federico Pasquaré Mariotto (Associate Professor, University of Insubria, Varese, Italy)
Corrado Venturini (Associate Professor, Bologna University, Italy)