Awakening Another Italian Volcano: A Neighbor to Vesuvius

Explore the wonders of the universe through CNN's Wonder Theory science newsletter. Stay updated with captivating discoveries, scientific advancements, and more. Don't dwell on Mt. Vesuvius, Italy's renowned active volcano that devastated Pompeii in 79 AD.

The current most perilous volcanic hazard in Italy remains relatively unknown: Campi Flegrei, also known as the Phlegraean Fields. Spanning 200 kilometers (125 miles) beneath the bay of Naples, as well as the neighboring islands of Capri and Ischia, this unpretentious plain was formed by a colossal supervolcano over 2 million years ago.

It is currently the location of numerous volcanoes, active for 39,000 years, with many of them positioned underwater. The area is also inhabited by 800,000 people, including villas, small villages, and shopping malls. Furthermore, a hospital is currently being constructed. The civil protection agency of Italy has identified over 500,000 locals residing in a "red zone," comprising 18 towns that are at the highest risk in the event of an eruption. According to the civil protection agency, an additional 3 million residents live just outside the eastern edge of the caldera in Naples.

Photo credit: Mariano Montella/Pacific Press/Shutterstock

Solfatara, also known as Solfatara di Pozzuoli, is a shallow volcanic crater located near Naples, in the Phlegraean Fields volcanic area. It is a dormant volcano that still releases jets of steam carrying sulfurous fumes. Its name originates from the Latin term "Sulpha terra," meaning "land of sulfur" or "sulfur earth." The formation of this crater dates back approximately 4000 years, and its last eruption occurred in 1198, likely a phreatic eruption caused by the interaction between groundwater and magma.

Until 2017, the crater floor served as a popular tourist attraction due to its numerous fumaroles and mud pools. The area is also renowned for its bradyseism, a geological phenomenon involving the rising and falling of land levels. The steam emissions from Solfatara have been utilized for medicinal purposes since Roman times.

This particular volcano gained significance as it is where the thermoacidophilic archaeon Sulfolobus solfataricus was first isolated. The name of this archaeon species is derived from the volcano, similarly to how other species belonging to the Sulfolobus genus are named after the areas of their initial isolation.

Caption: Solfatara di Pozzuoli, Italy - October 2, 2023. Image by Mariano Montella/Pacific Press/Shutterstock.

A second earthquake has struck near Naples within a week, raising concerns about a potential volcanic eruption. Italys National Institute of Geophysics and Volcanology (INGV) has observed increasing seismic activity in the region since December 2022, leading experts to believe that the long-dormant Campi Flegrei volcano may be reawakening. This volcano last erupted in 1538, resulting in the formation of a new mountain in the bay.

Less than 50 kilometers (31 miles) from Vesuvius, the densely populated region is susceptible to a geological occurrence called bradyseism. Bradyseism is characterized by repeated cycles of ground uplift and gradual subsidence. The last instance of such activity in the area was in 1984, where the ground rose 3.5 meters (11.5 feet) before slowly descending along with accompanying seismic activity, similar to the current situation.

Presently, the entire volcanic zone is undergoing positive bradyseism, resulting in upward movement of the ground. This phenomenon has triggered a surge in earthquakes, causing anxiety among residents and leading them to seek shelter on the streets. In September, the region experienced the strongest earthquake in 40 years, measuring a magnitude of 4.2. Shortly after, another earthquake of similar strength occurred.

Antonio Lira

In 2023, the number of earthquakes recorded in Campi Flegrei has exceeded 3,450, with 1,118 of them occurring in August alone. This figure is more than three times higher than in previous years, as indicated by data from INGV. Additionally, October witnessed over 500 earthquakes, with the most powerful reaching a magnitude of 4.0, followed by several aftershocks.

According to INGV, almost all of the earthquakes prior to May were of magnitude 3.0 or less.

It is widely believed by experts that the local residents should be prepared and equipped to handle the seismic activities and the potential eruption. On October 5th, the country's civil protection agency announced a revised evacuation plan, requiring the relocation of half a million individuals within a 72-hour timeframe. However, many locals are concerned that the existing road infrastructure may not be able to accommodate the extensive traffic. The previous evaluation of the evacuation plan conducted in 2019 revealed deficiencies and inadequacies.

Carlo Doglioni, the INGV's head, provided testimony to the Italian government's Environmental Commissions lower chamber on September 28 regarding the potential consequences of seismic activity.

According to his statement, there are two potential scenarios for the future of the situation in the Campi Flegrei region. The more favorable outcome would involve the ongoing bradyseism crisis subsiding, as it did between 1983 and 1984. However, the worst-case scenario would entail an eruption similar to that which occurred in 1538.

Whats behind the increase in activity

According to Dr. Giuseppe De Natale, a research director at the INGV in Naples, the current uplift cycle is linked to pressure beneath the caldera. The exact depth of the pressure increase remains uncertain, ranging between zero and 3.5 kilometers. De Natale presents two hypotheses to explain the current surge in seismic activity at Campi Flegrei.

The first possibility, potentially the most perilous, is the intrusion of magma originating from the magma chamber located approximately 8 kilometers beneath the surface, as stated by De Natale.

The second, deemed by him as more plausible, entails a substantial release of gases, termed "degassing," produced by the magma emerging from the deep magma chamber. According to him, this degassing occurring at the same depth as the magma chamber is the likely cause behind the tremors experienced in the ground.

De Natale explained that the issue lies with the rocks. He mentioned that shallow rocks have limited capacity to withstand high levels of pressure. Consequently, if the pressure surpasses a certain threshold, it could lead to the complete fracturing of the rocks. Such fracturing of the rocks is typically the underlying cause of volcanic eruptions.

Fumaroles, or vents, emit volcanic gases in the Pisciarelli area of Campi Flegrei on October 23, 2023.

Ivan Romano/Getty Images

Dr. Benedetto De Vivo, a former professor of geochemistry at the University of Naples and a bradyseism expert, concurs that the crater is undergoing degassing. However, he posits that the uplifted terrain is not solely a result of magma ascent, but rather the receding of magma beneath the caldera. Nevertheless, De Vivo asserts that it is impossible to ascertain the exact nature of these phenomena.

Despite opposition from local residents regarding the potential for increased seismic activity, De Natale received approval in 2009 to lead a team of volcano experts from 18 countries on a mission in 2012. This mission aimed to drill a pilot hole that would reach a depth of 501 meters (1,644 feet) into the caldera, in order to gain a clearer understanding of the situation. However, the drilling project was halted before it even began by Rosa Russo Iervolino, who was the mayor of Naples at the time. She expressed concerns for the safety of the population. In 2012, after Iervolino left office, the project was briefly reinstated by the new mayor, Luigi di Magistris. Unfortunately, due to a lack of funding, only the borehole was drilled.

De Natale has stated that there are no plans to resume drilling, and the current city government has informed CNN that they prioritize other areas of concern when it comes to budget allocation for city projects. These areas include the development of improved evacuation plans for both Mount Vesuvius and the Campi Flegrei region.

Planning around a natural enigma

Supervolcanoes are among the most perplexing and least understood natural threats in the world.

What distinguishes a supervolcano from an ordinary volcano is the amount of volcanic material it has ejected during past eruptionsa reflection of the volcanos explosive power.

An October 6 still from a US Geological Survey livestream shows Halemaʻumaʻu crater at the summit of the Kīlauea volcano.

USGS

Hawaii's Kīlauea volcano, which is currently active, experienced more than 320 earthquakes in a span of 24 hours, as reported by officials.

A supervolcano is classified as one that has released over 240 cubic miles of material and has been given a level 8 rating, which is the highest level of threat, on the Volcano Explosivity Index (VEI) by the US Geological Survey. The VEI measures the quantity of debris expelled, the height it reaches, and the duration of the eruption. The eruption that occurred at Yellowstone about 2.1 million years ago stands as one of the largest volcanic events ever documented. Similar in size to Yellowstone, other notable supervolcanoes such as Long Valley in California, Toba in Indonesia, and Campi Flegrei have also experienced eruptions in more recent history.

Scientists have documented 2,000 years of activity at Campi Flegrei. Excavations at the Roman Temple of Serapis in Pozzuoli revealed evidence of mollusc-made holes in the pillars, indicating that they were once submerged. The temple's base is connected to the sea through a network of underground tunnels, allowing for the observation of bradyseism-induced flooding and drainage over time. In 2016, the regional government classified the Campi Flegrei area as "yellow" in its warning system, signifying the second level of a four-level scale that assesses ground movement hazards for the population.

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In October, Italy's civil protection agency announced its decision to elevate certain regions to the orange level due to the increased intensity of recent activity. The INGV, responsible for validating this change, is anticipated to support the agency's initial request. By raising the alert level to orange, civil protection agencies will have the ability to evacuate the areas at highest risk from bradyseism and ongoing earthquakes more efficiently, thereby safeguarding the most vulnerable populations, according to officials.

During a meeting held on November 7, the INGV established that there are 15,000 buildings, including 125 schools and other academic facilities, situated in the high-risk zone. To address this concern, a directive will be issued on November 27, which will outline a revised protocol for evacuations, drills, and the possible temporary relocation of certain institutions until the ongoing bradyseism cycle diminishes.

The possibility of an eruption

According to a paper published in the scientific journal Communications Earth & Environment in June, parts of the volcano may be experiencing weakening caused by bradyseism. However, experts state that the situation still remains unpredictable. "The outcome we anticipate is contingent upon whether the ground continues to rise. If it maintains its current rate of movement, we can expect the frequency of small earthquakes per day to fluctuate over the course of weeks, ranging from just a few to several hundred events, as was observed in mid-August and late September," explained Christopher Kilburn, a coauthor of the study and a professor of volcanology at University College London.

Larger magnitude earthquakes are most commonly observed during earthquake swarms, indicating that the Earth's crust is being stretched to its breaking point. However, it should be noted that the occurrence of earthquake swarms does not necessarily guarantee an eruption.

"It is a similar pattern observed in all volcanoes that have remained dormant for many years," stated study coauthor Stefano Carlino, a volcanologist from the Vesuvius Observatory in a press release issued alongside the research paper.

The Solfatara crater, pictured here, is part of Campi Flegrei, which is a densely populated area.

According to Dr. Benedetto De Vivo, a retired professor of geochemistry at the University of Naples, the initial action to take in preparation should be to prevent population growth by enforcing a ban on further construction in Campi Flegrei. This region is renowned for its advanced development and should therefore be protected.

He also mentioned the need for improved evacuation routes consisting of wider roads, enabling residents in the densely populated area to evacuate within a 24-hour timeframe. "We are unable to build any additional homes in this region," he emphasized.

Italy's volcano experts demonstrate apprehension in providing precise forecasts regarding volcanic eruptions due to the concern of facing consequences if their predictions prove to be incorrect, as stated by the INGV.

Seven scientists were initially found guilty of manslaughter after assuring residents of LAquila in central Italy that they had no cause for concern regarding the heightened seismic activity in 2009. Tragically, an earthquake occurred shortly after one scientist had seemingly implied that it was safe to unwind and enjoy a glass of wine, resulting in the loss of more than 300 lives. Although the scientists were eventually vindicated on appeal, the incident profoundly impacted the scientific community in Italy, leaving them unsettled.

Royalty free 3d rendering of a photorealistic earth with a slice cut out. Realistic illustration with visible core.

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Scientists have reported that the Earth's core is currently experiencing leakage, although they do not believe it poses an immediate threat. They have pointed out that eruptions of the magnitude witnessed in the Campi Flegrei region approximately 39,000 years ago, known as "ignimbritic eruptions," are unlikely to occur in the near future, according to Natale's assessment.

Studying these potential massive eruptions, which are both rare and catastrophic, is a challenging but crucial aspect of vulcanology, according to Natale.

If a future eruption were to take place, Natale believes it would resemble the significant activity observed in 1538, which resulted in the formation of the 133-meter tall (463-foot-tall) Monte Nuovo cone, currently visible in the sea. However, considering the growth in population, the consequences of a similar event would likely be significantly different in the present day.

Katie Hunt contributed to this story.