On March 2, 1970, following the tremors caused by the Bradyseism that characterizes the area of the Phlegraean Fields, the authorities announced the first state of alarm and ordered the immediate evacuation of the Earth District.

The inhabitants of the heart of Pozzuoli were forced to leave their dwellings, many of which had been badly damaged or had collapsed, and were transported to other areas, to so-called public housing. In just two days, the Rione Terra took on the appearance of a ghost town.

In an instant, the citizens were ripped away from the walls where they had built an entire life and always called home. Far away from their affections and their everyday life, they had to build a new life for themselves.

The Rione Terra went from a working-class neighborhood to no man's land in a flash, suffering years of complete neglect, raped by looters who defaced its memory with continuous looting and vandalism. Works of art were lost and what was left in the rubble was taken away.

Bradyseism: a volcanic phenomenon

With the term Bradyseism indicates a particular natural event related to volcanic activity in a particular area. This phenomenon is characterized by a gradual change in ground level (about 1 cm per year) that can be defined in two ways: negative (or downward) if it involves a lowering of the ground, or positive (or upward) if, on the other hand it involves a raising of the ground. The effect of bradyseism is evident along the seashore through the progressive surfacing or submergence of buildings, coastlines and territories.

Phlegrean Bradyism

The phenomenon of bradyseism occurs often and especially in the area of the Phlegraean Fields, particularly in the Gulf of Pozzuoli.

In the area between Cape Miseno and Bay until Posillipo bradyseismic movements recur cyclically. There have been three phases in the historical evolution of the phlegrean bradyseism: a first descending phase (from the second century B.C. to the ninth century B.C.),which was followed by an ascending one (from the tenth to the sixteenth century B.C.) and finally a third phase, the last one, which still had a descending character (from the seventeenth century until 1970).

Between 1970 and 1972, the Phlaegrean bradyseism phenomenon reversed. It turned from negative to positive leading to a total ground uplift of about 160 cm. In the port of Pozzuoli, where the effects are most evident, the rise was at least 90 cm, while the coast had risen 20 cm.

The beaches, expanded, the piers and docks, raised and the connection that existed between the famous Temple of Serapis and the sea, turned out to be virtually useless.

At the same time there was intense volcano activity. Solfatara With more extensive and intense fumaroles and puffs of smoke.

The area of the Earth District was cleared due to excessive instability, and the inhabitants of the area were transported to the areas of Miliscola, Licola, Qualiano, Camaldoli and finally the Toiano district.

The phenomenon of Paroxysm

Bradyseism is characterized by times when the phenomenon intensifies, taking on the name of Paroxysm. The most important one occurred in 1538 when a mountain was suddenly born on the coast of Pozzuoli: Mount New.

In the period between 1983 and 1984 the phenomenon assumed a rate of 3 mm per day causing a total uplift of as much as 180 cm, numerous tremors (up to 500 per day) of varying intensity with epicenters, between the center of Pozzuoli and Quarto, occurred in the area.

This was caused by a magmatic intrusion that put the entire community on alert, in fact on August 24 of that year, the emergency plan was implemented.

On September 5, 1983, Pozzuoli was struck by a earthquake fifth degree that was felt throughout the Phlegrean coastal areas, inland areas, as far as Quarto and Pianura, Posillipo, and Vomero.

Curiosities about Phlegrean bradyseism

The naturalist Englishman Charles Lyell, who visited the Phlegrean area, was incredibly impressed by the evidence of sea level variations found on the columns of the Pozzuoli temple. He judged this case to be such a striking example that he used the image of the temple columns as a figure for the title page of his book Principles of geology (Principles of Geology) published in 1832 and which is considered the first modern book on geology.

Historical measurements and in modern times

In the past, the phenomenon of bradyseism in Pozzuoli, was measured with special instruments: the columns of the Temple of Serapis (the ancient Macellum) at Pozzuoli, which until 1983 were partially submerged by the sea. Today, however, they stand out above sea level and have characteristic holes dug by mollusks (lithodomas commonly called sea dates) up to a height of 6.30 m.

This undoubtedly attests that that was the maximum bradyseismic submergence suffered by the Phlegraean Fields in medieval times, however, do not be fooled: the water present in the Temple of Serapis today is due to an underlying thermal spring (called the Cantarello) and meteoric precipitation.

In modern times, however, extremely precise measurements can be obtained through satellite surveys. These compute data with respect to fixed points (in the form of coated metal pyramids) located in the various affected areas throughout the Gulf of Pozzuoli. The most recent surveys done with GPS by INGV have shown an uplift trend that has accelerated from June to August 2012 and since the beginning of December 2012 with a total uplift since January 2012 is about 9.5 cm.

Possible causes of bradyseism

The causes of the bradyseism are still unclear. An old theory looked for causes in magmatic waves, which, as they pass through, would lead to the characteristic change in the level of the Earth's crust at points where it is thinner.

In more recent times, however, it was argued that the phenomenon was due to volume changes in a magma chamber near the surface, however, a magma rise either solidifies, or leads to a volcanic eruption, never descending back to the starting level, so this theory is not acceptable.

Currently, changes in groundwater temperature are identified as the cause of bradyseism: increases or decreases in temperature would cause increased or decreased water vapor pressure in the subsurface with consequent deformation of the surface crust.

Bradyism in the rest of the world

In 2010, in Rabaul within 4 months prior to a major eruption, bradyseism caused the caldera to rise about 4 cm.

In the Sierra Nevada, however, the Long Valley caldera in California experienced a crustal uplift of about 80 cm between 1979 and 2000 as a result of underground volcanic activity. This uplift is related to the terminal phase of magma chamber activity.

The Rione Terra revival project.

In January 1992, the Campania Region began the first restoration work on the Earth District, which were, however, thwarted and slowed down by the constant arrests also and especially due to the mismanagement of the area.

Although, to date, most of the buildings have been renovated, Rione Terra is still traversed by cranes and workers, making it a curious tourist attraction. Visitors, attracted by its history and sad events, stroll curiously to observe this wacky open construction site overlooking the sea.

By 2022 Rione Terra will become a tourist site with luxury hotels and residences, according to the Pozzuoli City Council's plan. Today, thanks to the important work of the Puteoli Sacra, the Rione Terra is moving toward rebirth as a tourist and cultural site, you can enter for free while the archaeological tour can be purchased for €5.