Campi Flegrei, the playground of the rich and famous in Nero’s time

However, the party did not last long, because these beautiful people had unintentionally built their posh spa resorts and dream villas on an active super-volcano.  The upheaval of the Phlegraean Fields may be regarded as a harbinger of the down-fall of the Roman Empire.  I was only vaguely aware of the archeology and volcanism of the Phlegraean Fields until I paid a visit.  In May 2024, the international press had reported that hundreds of mild earthquakes had frightened the population of Naples.  At present, one million people live on an active volcano that they do not see!

                                           Geological map of the Campi Flegrei Caldera 

Located west of Naples, the Phlegraean Fields form a volcanic arc which encompasses the sinister Mount Vesuvius, and the idyllic island of Ischia.  The 39,000-year-old caldera of the super-volcano stretches tens of kilometers under the bay of Naples.  No less than 24 volcanic craters, many under water, have been recorded in this unstable but geologically and culturally fascinating region.  The awesome Campi have inspired many talented people, notably the Roman poet Virgil who sang its pleasant atmosphere.  Goethe noted that it was “The most wonderful region in the world; under the purest sky, the treacherous ground" and Madame de Staël described the Campi in such words: "The district of the universe where volcanoes, history and poetry have left more traces". 

In the VII century BC, frugal Greeks colons had settled in the region attracted by its mild climate and sheltered coves.  Three centuries later, their dynamic port cities were taken over by the ostentatious Romans who launched a real estate expansion program favoring leisure, maritime commerce and the military.  The glitterati of Roman Emperors built sumptuous villas in the Campi.  Julius Caesar, the Emperors Augustus Caesar, Claudius, Tiberius, Nero, Caligula and Septimus Severus vacationed here.  Hadrian actually died in the Campi spa town of Baiae and Nero had his mother Agrippina the Younger murdered near-by.  Scipio Africanus and Virgil were buried there.  In his Aeneid, Virgil found the entrance to hell in lake Avernus (Latin name for the underworld), a volcanic crater.  The author Pliny the Younger watched from his Campi seaside villa the unfolding of the 79 AD Vesuvius eruption which buried Pompeii and Herculaneum.

The Romans were spa fanatics and the Campi’s many hot springs added to the region’s appeal.  Consequently, they built the colossal spa resort of Baiae, the summus of self-indulgence.  In Pozzuoli, they built the Flavian amphitheater to indulge in their addiction to fun and games; it is Italy’s third largest.  A great number of minor-sized temples, theaters and other entertainment venues sprinkle the Campi.  The amphitheater’s claim to fame is the martyrdom of Saint Gennaro, Naples ‘patron saint.  Fashionable Baiae was so over-the-top that it put modern Monte Carlo to shame.  Philosopher Seneca described the town as a “vortex of luxury” and a “harbor of vice”, the Roman hedonistic lifestyle pushed to the extreme.

Nature punishment came progressively, cracks started to appear in the walls of the decadent elites ‘McMansions, as if the invisible super-volcano was taking vengeance for suffering so much indignity.  The ground started sinking moderately and occasionally shaking.   By the end of the IV century AD, slowly but gradually, the resort of Baiae and the costal villas fell into the sea.  Without knowing, the Romans were facing a destructive earth movement called bradyseism (from the Greek bradus=slow and sism=movement).  It is both a gradual subsidence and uplift of parts of the Earth’s surface.  It is caused by movements of the underground magma chamber and associated hydrothermal activities.  The Macellum, the Roman market of Pozzuoli (photo) subsided (6m) under the sea; but since the 11^th century the area is in the process of uplifting.  These earth movements cause recurrent, but temporary evacuations.

The Macellum is still below sea level and partly flooded.

                                                  Inside Pozzuoli Amphitheater

During a volcanic eruption of the Solfatara volcano, the amphitheater was partly buried, and later abandoned.  The shallow Solfatara crater is famous for its bubbling mud pools and fumaroles clouds.  In 1538, a new volcano was formed burying several villages, it is the newest mountain in Europe! 

Virgil had got it right when he designated the grotto of lake Avernus the entrance of Hades.  Sulphur gases coming from the bowels of the earth kill slowly.  

We spent a whole day in the Campi Flegrei, both a fascinating and frustrating visit.  Bradyseism is still on-going (raising 2cm/month).  The amphitheater tour was cut short, parts of the building are currently too dangerous and off limits.  We walked around Cuma but skipped Baiae, the Italian Atlantis because the best part is under the sea.  The underwater guided tour requires some preparedness.

39,000 years ago, the Campi Flegrei eruption caused the extinction of the Neanderthals; a new eruption could be as devastating.