Phlegrean Fields (Campi Flegrei)

Italy is at the junction of two tectonic plates (African and Eurasian) and at the top of two major fault lines, so high seismicity is common for this region. Read more: Earthquakes in Italy

The name "Phlegrean Fields" ("scorched lands") is taken from ancient mythology - the so-called place where the gods, led by Zeus, defeated the giants - giants generated by Gay.

Caldera and its volcanoes

The area of ​ ​ the caldera is about 100 km ² (10 × 10 km). Most of it extends under the Gulf of Pozzuoli (Italian: Golfo di Pozzuoli) and covers the islands of Vivara, Nizida, Ischia and Procida. The land area is bounded by the shores of the bay, the coastal strip of the Tyrrhenian Sea and the northwestern outskirts of Naples.

Within Campi Flegray are a large number of fumaroles, more than 150 pools of boiling mud, 24 craters and several auxiliary cones^[1].

Satellite map of the Phlegrean Fields, 2006

According to scientists, a 400sq km igneous reservoir^[2] is only about 3km below the surface of the caldera, as a result of which the earth's crust literally floats in hot rocks and makes the so-called bradyseismes (terrestrial vertical oscillations)^[1].

Eruptions 35 thousand - 10.5 thousand years ago^[3]:

• Posillipo – Collina dei Camaldoli – Monti San Severino – Monte di Cuma (parte tufacea) – Monte di Procida
• Capo Miseno (Bacoli)
• Bacoli e Punta Pennata (Bacoli)
• Monte Gauro (Pozzuoli)
• Quarto.

Eruptions 10.5-8 thousand years ago:

• Isola di Nisida (Naples)
• Montagna Spaccata (Quarto Flegreo)
• Fondi di Baia e Golfo di Baia (Bacoli) [8,400 years ago]

Eruptions 8 thousand years ago - 1538 AD:

• La Starza (Pozzuoli)
• Monte Cigliano (Pozzuoli)
• Agnano (Napoli) [4.4 thousand years ago]
• Monte Olibano (Pozzuoli) duomo trachitico dell'Accademia Aeronautica [4.8 thousand years ago]
• Monte Spina (Naples) [4.1 thousand years ago]
• Solfatara (Pozzuoli) [3.9 thousand years ago] - is the main tourist attraction in the area of ​ ​ the Flegrei fields. Although the volcano is considered active, its activity for two thousand years has been the release of sulfur dioxide and water vapor through fumaroles. Solfatara plays the role of the valve that closes the magma, which is located under the Phlegrean fields. Solfatara Crater has an elliptical shape with a diameter of 770 meters, a perimeter of 2.3 km. The highest part of the crater, called Mount Olibano, rises to an altitude of 200 meters above sea level, the lowest part is located at an altitude of 92 meters above sea level. In Roman mythology, Solfatara was considered the home of the god Vulcan.
• Lake Averno (Pozzuoli) [3.8 thousand years ago]
• Cratere degli Astroni (Naples) [3.7 thousand years ago]
• Cratere Senga [3.7 thousand years ago]
• Monte Nuovo (Pozzuoli) [1538 AD]

In addition to volcanoes visible on the surface, the caldera also includes^[3]:

Islands (discussed):

• Monte Epomeo (Isola d'Ischia)
• Isolotto di San Martino (Monte di Procida)
• Nisida
• Procida (diversi crateri: Chiaia, Carbonchio, Pozzovecchio)
• Isola di Vivara
• Golfo di Genito — tra Procida e Vivara

Planar surfaces:

• Fuorigrotta (Naples)
• Pianura (Naples)
• Pisani (Naples)
• Soccavo (Naples)

Stages of development of the volcano

39 thousand hp: mega-eruption and extinction of part of the Neanderthals

The earliest activity of Campi Flegrei began about 39,280 years ago and was accompanied by a powerful volcanic eruption and the release into the atmosphere of about 200 km³ of the volcanic material^[1].

According to other sources, mega-ejection consisted of two phases. At the first stage (Plinian), super-eruption led to the formation of a giant ash column 44 km high and covered with 54 cubic meters of ash. km the entire territory of Southern Italy.

In the second stage (Plinian and Ignimbrite), the caldera erupted about 154 cubic meters. km of volcanic materials, and the total amount of deposits accumulated during the two phases was equivalent to eight volumes of Mount Everest.

According to other sources, the second phase released more than 450 cubic meters into the atmosphere. km. The total volume of particles exceeded 500 cubic meters. km^[4].

The centers of supervolcanoes are located much closer to the surface of the earth than in ordinary volcanoes and are huge magmatic reservoirs - the area of ​ ​ their horizontal section is accordingly large. According to one version, the eruption of the supervolcano began with the fact that magma melts and breaks the layer of the earth's crust above itself, protruding on the earth's surface a huge hump several hundred meters high and 15-20 kilometers in diameter.

Then the pressure increases, magma is looking for a way out. Along the perimeter of the supervolcano, numerous vents and cracks arise - and then its entire central part collapses down into the fiery underworld. Collapsed rocks, precisely a piston, sharply release huge volumes of magma and gases from the bowels - and they are thrown into the sky by giant fountains of lava and cyclopean clouds of ash. Volcanologists have never seen such a phenomenon.

When the eruption of the supervolcano ended, a huge caldera remained from it, inside which a huge valley formed - a kind of "lid" over the igneous hearth. Part of such a "cover," its edge, just can be the Phlegrean Fields.

Data for 2018

The mega-eruption coincided in time with the eruptions of the volcanoes Kazbek in the Caucasus and St. Anna in the Southern Carpathians. According to seismologists and paleoclimatologists, it became one of the reasons for the "volcanic winter."

Sulfur has increased over Europe, absorbing and scattering sunlight. In the year following the eruption, temperatures across the planet dropped by 2 degrees Celsius, with a 5-degree decline in Western Europe.

Volcanic emissions, gradually settling, left behind a trail of rock that, in the shape of a wedge, stretched from southern Italy northeast to the Southern Urals.

2016 Study Data

The rock covered more than 1.1 million square meters with an ash layer. The affected were, among other things, the Black Sea region and the Caspian Sea. Ash eruptions were discovered, including during excavations in Kostenki, Voronezh region of Russia. The largest layers of ash have been found in present-day North Macedonia, Bulgaria and Romania. In the eastern regions of the Mediterranean, the thickness of ash layers reached 10 cm.

From southern Italy to Romania, the ash layer reached 1 meter. According to the volcanic activity scale, the eruption of the Phlegrean fields had 7 points out of 8 possible.

The ash, coupled with a drop in temperature, caused vegetation to be oppressed. Years followed when there was not even a moderate summer warming. Plants stopped growing completely; without sunlight in sufficient amounts, photosynthesis stopped. Animals that were able to survive the eruption migrated en masse from vast spaces from Italy to the Urals. This eruption was the strongest in Europe for a period of 200 thousand years.

According to one version put forward by anthropologists, the eruption could become either the main or one of the main reasons for the extinction of Neanderthals in a significant part of their range from Central Europe to the Caucasus. The volcanic winter that began found the Neanderthal population in this part of Europe in a position where the animals they hunted left large areas. Neanderthals were focused specifically on meat consumption, hunting, they did not know agriculture and did not know how to feed themselves without the presence of herbivores. The remains of two Neanderthals, discovered in the Mezmay Cave (Caucasus, Russia), gave a number of valuable information. They hunted four species of bison. After the second cycle of eruptions, the content of harmful substances in the soil and atmosphere increased, bone tests show that the norm was exceeded several times. The ecology has deteriorated sharply, animals have disappeared, plant pollen is not present in sediment analyzes during this period^[1]?.

The authors of this study believe that the environmental crisis also prevented the first wave of settlement of Europe by Sapiens. However, people of modern anatomy were lucky in the sense that during this period they lived in more southern latitudes, mainly in Africa, and avoided the direct consequences of the disaster. Only when the climate stabilized in the northern latitudes, did modern man begin to develop new territories partially freed from Neanderthals^[5]

35-10.5 thousand years ago: a volcano centered on the site of Pozzuoli Bay

Second Phlegrean period. Between 35 thousand and 10.5 thousand years ago, a volcanic yellow tuff formed in the caldera area, which makes up the remains of a huge underwater volcano. It had a diameter of about 15 km, and in its center was Pozzuoli Bay. For approximately 12,000 years, Campi Phlegrei experienced its last major eruption, which formed a smaller caldera inside the main one.

3.8 thousand years ago: the appearance of Lake Averno

In the interval after 8,000 years, small eruptions occurred in the caldera, as a result of which Lake Averno appeared.

1538: Monte Nuovo Volcano Formation

During the eruption from September 29 to October 6, 1538, the cinder cone of Monte Nuovo (New Mountain) was formed in the caldera, capable of producing colossal explosions with an index of VEI-7 on an 8-point explosion hazard scale - like the eruption of Tambora in 1815. From 1970 to 2015, the soil on it rose by 2 meters, so it carries a serious threat to the inhabitants of the Campania^[1] region].

2012-2013: 11 cm soil rise with emissions of gas and sulfur dioxide in Solfatar Crater

Since the 1980s, soil deformation has been observed on Campi Flegrei, in connection with which in 2012 scientists raised the danger status of the volcano from "green" to "yellow."

According to research by the National Geophysical Institute of Italy, in the rest of the caldera (in addition to the Monte Nuovo volcano) from January 2012 to June 2013 it was characterized by a rapid uplift of 11 cm at a peak speed of 3 cm per month in December 2012. Soil uplift is accompanied by emissions of carbon dioxide and sulfur dioxide on the territory of the Solfatar crater.

Solfatara Crater

In the mid-2010s, the Phlegrean fields received increased attention from volcanologists, since their eruption could cause considerable damage throughout Europe and northern Africa^[1].

2016

Study: Soil uplift is associated with gas pressure

In June 2016, ​​na Goldschmidt conference in Yokohama (Japan), the results of a new study by Italian geochemists were presented, which indicate that the uplift in the Campi-Phlegrei caldera area is due to gas pressure, and not due to a magma surge, as previously thought^[6]

Due to geological instability, soil in the area of ​ ​ the Flegreysky fields can rise and fall several meters in just a few years. A similar event was observed in 1982-1984, when the surface of the caldera rose to a height of 1.8 meters. Most scientists believed that deformation was associated with mixed magmatic and hydrothermal activity, however, the latest study by geochemists from the Second University of Naples indicates the involvement of volcanic gases in the process.

Temperature rise of hydrothermal reservoir in Solfatar 1982-2015^[7]

According to Professor Roberto Moretti (lead author of the study), during his work, experts analyzed the geochemical data of the caldera over the past 30 years and came to the conclusion that the uplift is not associated with magma migration, but with hydrothermal activity supported by deep magmatic gases.

On the one hand, this is good news, since in this case the likelihood of an eruption can be somewhat reduced. On the other hand, the transition from hydrothermal to magmatic activity can occur from any time, that is, experts cannot say that everything is fine on Campi Flegrey. Caldera is still an unpredictable place that poses a threat not only to Italy but to the whole of Europe.

According to scientists, a new interpretation of the activities of the supervolcano requires direct access to its underground area, but there is still debate in the scientific world regarding the safety of drilling a caldera. Commenting on the presented study, Professor John Blundy from the University of Bristol argues that hot gases and magma are the first candidates for the causes of soil deformation, but have completely different consequences for future volcanic activity.

"Moretti makes a convincing case for gas, which can be used on other restless volcanoes," the scientist said.

Gas pressure has reached a critical point

In December 2016, it was announced that the Campi Flegrei volcano was showing signs of awakening. Pressure inside the giant is approaching its breaking point, according to new research by Italian and French experts, which could lead to an eruption later on. The results of the study were published on December 20, 2016 in the scientific journal Nature Communication.

According to Giovanni Chiodini, a research fellow at the National Institute of Geophysics and Volcanology in Bologna, raising magma causes hydrothermal rocks to heat, which will eventually lose their mechanical strength and cause eruptive processes to accelerate towards critical conditions.

"We cannot say for sure when the volcano will begin to erupt, but it poses a great danger to 500 thousand people who live inside and near the caldera," says a specialist[8].

Recently, the rate of soil uplift has increased. According to Chiodini, there is an urgent need for further study of the Flegrean fields, since a similar pattern was observed before the eruptions of two other dangerous volcanoes - the Rabaul caldera in Papua New Guinea and the Sierra Negra in the Galapagos Islands.

2017

Death of three people in Solfatara crater

On the evening of September 12, 2017, a child of 11 years and his parents fell into the failure of the Solfatara volcano crater.

A family from Venice spent the last day of vacation in Naples. 11-year-old Lorenzo came close to the recent depression in the crater formed after intense rains and failed. Father Massimiliano Carrer (45-year-old engineer) and mother Tisiana Zaramella (42-year-old Venice airport employee) tried to return him, but at one point the ground under their feet also crumbled: all three were in the resulting hole with boiling mud (carbon monoxide) three meters deep. The incident occurred at the largest fumarola in the area - Bocca Grande (Big Mouth).

The rescuers were informed about the incident by the owner of a bar located at the entrance to the park, into which a tearful seven-year-old boy Alessio, the youngest son and brother of those killed, came running^[9] crater^[9].

The bodies of the dead were pulled out by rescuers in special equipment. According to preliminary data, death occurred from inhalation of poisonous gases. Rescuers explained that the dead did not have the slightest chance to survive, since the temperature in the crater of the volcano exceeded a thousand degrees^[5].

The photo shows that the failure is located on an unfenced area.

Tourist access to the volcano's crater was opened in 1900. For 2017, the volcanic park is private property, it is managed by VolcanoSolfatara srl. Tens of thousands of visitors paid for tickets each year to admire the mud and fumaroles. This is the first fatal accident in the park^[10].

Investigation into the tragedy. Solfatary Crater is closed to the public, including scientists

Since September 12, 2017 - the day three people died in the Solfatara crater, the place is closed to the public, including scientists. The Vesuvius Volcanic Observatory has launched a warning: "Geochemical stations are closed and we cannot conduct a tracking campaign."

The tragedy was followed by an investigation coordinated by prosecutor Giuseppe Lucantonio and a number of technical examinations. The entire territory of Solfatar was subjected to preventive seizure by the investigating judge Claudia Picchiotti at the request of the prosecutor. In fact, since October 26, 2017, along with the geological park, the campsite, swimming pool and sports fields have been closed.

All activity by VulcanoSolfatara Srl, a private company running the park under Giorgio Angarano, has been blocked over allegations related to the September 12 tragedy. Access to the crater is prohibited to everyone, including operators of the National Institute of Geophysics and Volcanology, who have been monitoring the zone for many years. Data collected by the Vesuvius Observatory, the Neapolitan department of the Research Institute, contributes to the ongoing analysis of geophysical and geochemical phenomena in the Campi Phlegrei caldera.

In 2012, scientists raised the danger status of the volcano from "green" to "yellow," due to the gradual increase in the activity of observed phenomena. The institute produces weekly and monthly bulletins on the state of activity of the volcano, using stations and data from periodic studies. Also an important task is to alert the Civil Protection Department in the event of abnormal signals that may represent a hazard index. Observatory director Francesca Bianco is concerned:

"Geochemical plants need maintenance, filters clog, and for months we no longer get any data on the chemical composition of fumarol and the CO2 flow, indicating a magmatic component." We interrupted thirty years of observations, "Bianco complains. "And if in 2012 we were able to raise the alert level, it was due to data coming from Solfatara. We can continue to collect data from Fumarol Piscyarelli, but that's not enough. The observation is multivariable, and if one of these parameters is missing, this becomes a problem. Now we are forced to stop data collection and this is a very serious problem, especially for a volcano like the Phlegreian Fields[11].

2018: A new phase of pre-eruption capacity building

A team of scientists from Switzerland, Britain and Italy analyzed the materials formed after the previous eruptions of the Phlegrean fields. Based on these data, they concluded that volcanoes in the area are again preparing a massive eruption, but this preparation can stretch for hundreds of years. The work is published in the journal Science Advances.

In total, the researchers looked at 23 eruptions of the Phlegrean fields, the most recent of which occurred in 1538.

The authors combined petrological surveys with a thermomechanical model to determine how the magmatic field system transitions from small and frequent eruptions to large ones. They found that magma, saturated with water and carbon dioxide and released in 1538, coincided with the one that preceded Super Exile. In their opinion, these findings prove that the subvulcanic system of the Phlegrean fields has entered a new phase of capacity building. A climax in the form of a powerful new eruption should occur in the future, but it is not yet possible to accurately determine its point on the timeline.

See also

• Ol Doinyo Lengai
• Santorini

Notes