Earthquakes under the Campi Flegrei caldera during 26 Oct- 3 Nov 2026 (image: INGV-OV)The Campi Flegrei volcanic caldera near Naples continues to show signs of unrest, with ongoing ground uplift, frequent small earthquakes and elevated gas emissions. According to the latest INGV weekly report, 64 earthquakes were recorded between 26 October and 1 November, while the ground continues to rise at approximately 1 cm per month. Meanwhile, volcanic CO₂ emissions are causing serious problems for local infrastructure: a railway tunnel connecting Naples with Pozzuoli remains closed because of hazardous gas concentrations, with no reopening date in sight.Two earthquake swarms near Pozzuoli and SolfataraSeismic activity continued across the Campi Flegrei caldera during the reporting period. Of the 64 earthquakes detected, 42 events with magnitudes of 0.0 or greater were located by the monitoring network. The strongest reached a magnitude of 2.4 (±0.3).Fourteen earthquakes occurred during two distinct seismic swarms. The first began at 10:39 UTC on 26 October southwest of the Solfatara crater. It consisted of four earthquakes with magnitudes between 0.0 and 2.2. The second swarm started at 16:30 UTC on 27 October in the Pozzuoli area and included ten earthquakes, with the strongest reaching magnitude 2.4.Most of the larger earthquakes were located at shallow depths of approximately 1–3 km, consistent with the shallow seismicity frequently observed within the caldera.An interesting exception was a small magnitude 0.4 earthquake recorded on 30 October at 03:59 UTC near Bagnoli, in the southeastern part of Campi Flegrei. Its hypocenter was located at a depth of approximately 6.8 km, considerably deeper than most other earthquakes recorded during the week.INGV notes that earthquakes at such depths have occasionally occurred in this part of the caldera in the past.Although the earthquakes were relatively weak, the continuing seismicity reflects the ongoing unrest affecting Campi Flegrei, where changes in pressure and stress within the volcanic and hydrothermal systems can produce repeated episodes of rock fracturing.Ground uplift continues at approximately 1 cm per monthGround deformation remains one of the most important indicators of activity at Campi Flegrei. According to INGV, the average uplift rate in the area of maximum deformation has remained at approximately 10 ± 3 mm per month since early February 2026.Measurements at the RITE GPS station in Pozzuoli, near Rione Terra, indicate that the ground has risen by approximately 33 cm since January 2025, after correcting for the sudden displacement associated with the strong earthquake swarm of 31 July 2026.Without this correction, the measured cumulative uplift amounts to approximately 32 cm.The July swarm, which included an earthquake of magnitude 4.7, caused small but measurable sudden displacements at several GPS stations in the central part of the caldera. These changes have since been analyzed and incorporated into the deformation measurements. Importantly, the corrected data show no significant changes in the overall deformation pattern following the July earthquakes.The continued uplift is part of the ongoing bradyseismic activity at Campi Flegrei, a process in which the ground gradually rises or subsides as pressure conditions change beneath the caldera.Although the current uplift rate is relatively modest, the accumulated deformation remains substantial and demonstrates that the processes responsible for the unrest are continuing.Elevated carbon dioxide emissions at PisciarelliGeochemical monitoring provides further evidence of persistent activity within the hydrothermal system. In the Pisciarelli area, on the northeastern outer flank of the Solfatara crater, carbon dioxide emissions from the ground remain elevated.Measurements from the FLXOV8 monitoring station indicate that CO₂ flux has increased during recent weeks. Although values decreased slightly during the latest reporting period, they remained high compared with previous periods.A second monitoring station nearby also recorded a moderate increase in CO₂ emissions during the week. INGV notes that if these elevated values persist over the coming weeks, they would confirm a renewed increase in degassing activity at Pisciarelli.Longer-term measurements from another station, V07, show that carbon dioxide emissions increased between August 2024 and February 2025 before entering a period of slight decline. During recent months, however, a renewed upward trend has become apparent.The observations are consistent with the longer-term evolution of the Campi Flegrei hydrothermal system, which has experienced increasing temperatures, pressure and gas emissions over several years.Nevertheless, local conditions can also influence the measurements. INGV points out that variations in the water level of the Pisciarelli mud pool and in gas emission temperatures appear to be increasingly affected by meteorological conditions.Solfatara fumarole temperatures remain highTemperatures measured at the Solfatara crater remain elevated. The BG fumarole, one of the main gas emission sites within Solfatara, maintained an average temperature of approximately 173°C during the reporting period. A nearby sensor recorded a similar average of 172°C.These temperatures are consistent with the significant increase observed over recent years and reflect the continued heating of the hydrothermal system. At Pisciarelli, a fumarole located approximately five meters from the main emission area maintained an average temperature of around 94°C, close to the condensation temperature of the emitted steam under local conditions.The combination of high fumarole temperatures and elevated carbon dioxide emissions indicates that the hydrothermal system remains strongly active. However, the latest measurements do not show a sudden change that would suggest an imminent escalation of volcanic activity.Volcanic CO₂ emissions keep railway tunnel closed near PozzuoliThe effects of volcanic gas emissions at Campi Flegrei are not limited to the monitoring stations. They are also causing serious disruption to daily life in the densely populated area west of Naples. Train services on Naples Metro Line 2 between Napoli Campi Flegrei and Pozzuoli remain suspended because of dangerous concentrations of carbon dioxide inside the railway tunnel beneath Monte Olibano.CO₂ is particularly hazardous in enclosed or poorly ventilated spaces. The gas is heavier than air and can accumulate in low-lying areas, potentially displacing oxygen and creating life-threatening conditions for passengers and railway workers.Rail infrastructure operator Rete Ferroviaria Italiana (RFI) has installed powerful ventilation turbines inside the tunnel to reduce gas concentrations. These measures have produced significant improvements, and several tests have been carried out to assess whether railway operations could safely resume.However, the results have so far been insufficient to authorize reopening. At a coordination meeting on 3 November, Campania's regional civil protection councillor Fiorella Zabatta strongly criticized RFI for failing to present a concrete solution or a timetable for restoring the service.According to the regional government, months of discussions and technical assessments have not resulted in a workable reopening plan. The continuing closure is affecting thousands of commuters, students and workers who depend on the railway connection.The mayors of Pozzuoli, Bacoli, Quarto and Monte di Procida also expressed frustration. Pozzuoli mayor Luigi Manzoni reportedly left the meeting in protest after learning that the line would remain closed indefinitely.RFI, meanwhile, emphasized that passenger and worker safety must take priority. Although ventilation has significantly reduced CO₂ concentrations, the company considers that the conditions required for safe railway operations have not yet been met.Further measures are being evaluated, including additional ventilation and structural interventions. Works are reportedly scheduled to begin in mid-December, but there is currently no confirmed reopening date.The situation illustrates a particular challenge posed by the ongoing unrest at Campi Flegrei: volcanic hazards can have substantial consequences even without an eruption. Unlike a temporary ash cloud or a single earthquake, persistent CO₂ emissions may require continuous technical measures to keep underground infrastructure safe. It remains uncertain whether ventilation alone will be sufficient to manage the problem over the longer term. The area's continuing seismic activity adds another concern, as stronger earthquakes could potentially affect underground infrastructure or alter pathways through which gas migrates. However, there is currently no evidence that such damage is responsible for the continuing closure.Outlook: Continued unrest, but no significant short-term changes expectedThe latest monitoring data indicate that Campi Flegrei remains in a state of persistent volcanic unrest, characterized by ongoing ground uplift, repeated small earthquakes and elevated gas emissions.The renewed increase in carbon dioxide flux at Pisciarelli is one of the more noteworthy developments. If sustained, it could indicate a further intensification of degassing within this part of the hydrothermal system. At the same time, ground uplift has continued at a relatively steady rate since February, and the recent earthquakes have not been accompanied by significant changes in the overall deformation pattern.In its latest assessment, INGV states that the available monitoring data do not indicate developments suggesting significant changes in volcanic activity in the short term. This does not mean that the unrest has ended or that future changes can be excluded. Campi Flegrei remains a closely monitored volcanic system, and changes in seismicity, ground deformation or gas emissions could provide important information about its further evolution.For now, the observations point to a continuation of the existing unrest rather than a clear acceleration towards an eruption.Sources: - INGV – Osservatorio Vesuviano, Campi Flegrei Weekly Bulletin, issued 3 November 2026, covering 26 October–1 November 2026.- Gazzetta di Napoli, 3 November 2026- Corriere del Mezzogiorno, 3 November 2026- Regione Campania, official statement of 3 November 2026Carbon dioxide degassing over the past 10 years are gradually rising (image: INGV-OV)