Campi Flegrei News: Insights into Latest Volcano Activity

Recent activity at Campi Flegrei, a large volcanic caldera in southern Italy, has drawn increased attention from scientists and local authorities. This geologically complex region requires continuous monitoring to assess potential hazards.

Researchers track deformation, gas emissions, seismic disturbances, temperature fluctuations, and hydrothermal changes to evaluate risks.

Crustal Deformation

The ground beneath Campi Flegrei is in constant flux, with shifts in elevation and horizontal displacement offering critical clues about subsurface activity. Satellite-based interferometric synthetic aperture radar (InSAR) and global positioning system (GPS) data reveal a pattern of uplift, particularly in the central and eastern caldera. This deformation is largely attributed to the pressurization of underground reservoirs, where accumulating magmatic gases and hydrothermal fluids exert stress on overlying rock. Since 2005, the region has experienced approximately 90 centimeters of uplift, with acceleration in recent years raising concerns.

Uplift rates, historically averaging 5-10 millimeters per month between 2012 and 2020, have recently increased to nearly 15 millimeters per month in some areas. This acceleration suggests growing energy accumulation within the caldera, which could influence future eruptive potential. Ground-based tiltmeters and strain gauges have recorded episodic pulses of deformation, often coinciding with increased seismicity, reinforcing the hypothesis that pressurized fluids are moving through the system.

Geophysical models suggest the primary deformation source lies 3-4 kilometers below the surface, where magmatic intrusion and hydrothermal pressurization are occurring. Low-frequency seismic tremors, combined with uplift, indicate gas-rich magma interacting with the hydrothermal system, leading to episodic pressure fluctuations. This interaction weakens rock integrity, increasing the likelihood of fracturing and potential vent formation.

Changes In Volcanic Gases

The composition and concentration of volcanic gases at Campi Flegrei provide insight into subsurface activity. Carbon dioxide (CO₂) and sulfur dioxide (SO₂) are closely monitored, as fluctuations can signal changes in magma movement or pressurization. Over the past decade, gas monitoring stations in the Solfatara and Pisciarelli fumarolic fields have recorded rising CO₂ emissions, increasing temperatures, and enhanced gas discharge rates, suggesting a stronger connection between surface vents and underlying magma reservoirs.

Isotopic analysis of CO₂ indicates a growing magmatic signature, with δ¹³C values shifting accordingly. Helium isotope ratios (³He/⁴He) have also trended upward, reinforcing the presence of fresh magmatic input. Elevated helium levels, often linked to deeper mantle-derived contributions, can precede increased volcanic unrest.

SO₂ emissions, though lower in concentration than CO₂, provide critical information on volcanic behavior. Periodic surges in SO₂ flux, often coinciding with seismicity and deformation, suggest transient magmatic gas releases. Variability in hydrogen sulfide (H₂S) emissions, with increased H₂S/CO₂ ratios, points to hydrothermal system shifts influenced by deeper magmatic heat sources.

Seismic Swarms

Seismic swarms—clusters of low-to-moderate magnitude earthquakes occurring in rapid succession—offer insight into the evolving state of the caldera. These events indicate persistent subsurface stress, typically linked to fluid migration, fault reactivation, or pressure changes. Over the past year, seismic activity has intensified, with some swarms producing hundreds of tremors in a short period.

A notable swarm in late 2023 recorded over 1,100 microearthquakes, with magnitudes reaching 4.2. Concentrated in the Pozzuoli region, these quakes occurred at depths of 2 to 4 kilometers, likely driven by pressurized fluids forcing through rock fractures. This movement generates stress along fault lines, potentially destabilizing the subsurface. Seismometers have detected an increase in high-frequency events, indicative of brittle rock failure, alongside occasional low-frequency tremors that may signal deeper magmatic activity.

Repeated stress on fault structures weakens rock formations, increasing susceptibility to future displacement. In densely populated areas, ground shaking can exacerbate structural vulnerabilities. Historical records from the 1982-1984 unrest highlight how prolonged seismic activity can precede significant geological changes. Comparing recent trends with past patterns helps refine hazard assessments and risk mitigation strategies.

Surface Temperature Patterns

Thermal anomalies at Campi Flegrei reveal shifts in geothermal activity. Satellite-based imaging and ground-based infrared sensors have documented rising surface temperatures in fumarolic fields, particularly in Solfatara and Pisciarelli. Over the past decade, localized temperature increases exceeding 5°C suggest intensified heat transfer from deeper geothermal reservoirs, potentially linked to increased convective circulation or changes in subsurface permeability.

Episodic spikes in surface temperatures often correlate with periods of heightened unrest. These fluctuations may result from hydrothermal system shifts altering heat distribution. Ground-based thermal cameras have detected transient hotspots, sometimes in new locations, indicating reactivated fractures or new geothermal fluid pathways. Increased thermal stress can contribute to ground weakening and localized subsidence.

Hydrothermal Signals

The hydrothermal system at Campi Flegrei serves as a conduit for heat and gas transfer between the magma and surface. Recent evidence suggests intensified interactions between rising magmatic gases and underground water, leading to changes in fluid composition, pressure, and discharge rates. Pisciarelli, in particular, has seen more vigorous boiling mud pools and steam vents, along with increased gas flux and thermal output.

One concerning trend is the rise in water acidity and mineralization, indicating enhanced gas-water interactions at depth. Chemical analyses show elevated dissolved sulfates and chlorides, suggesting hotter, gas-rich fluids are mixing more extensively with shallow groundwater. Acidic fluids accelerate mineral dissolution, weakening rock formations and increasing the potential for ground deformation or localized collapses.

Sudden steam-driven explosions, or phreatic bursts, in historically active areas highlight the risks associated with these hydrothermal changes. Pressure accumulation in confined spaces can lead to abrupt surface disruptions, emphasizing the importance of continuous monitoring.