Recent studies have unveiled unusual seismic activity within the Campi Flegrei caldera, one of Italy's most closely monitored volcanic regions, indicating potentially significant geological unrest. Since early 2021, the caldera has been experiencing burst-like swarms of volcano-tectonic (VT) earthquakes characterized by remarkably short intervals between events, which have raised alarms for residents of the densely populated areas surrounding the caldera.
The Campi Flegrei caldera, located near Naples, has been under surveillance due to its complex geological history, including intermittent periods of unrest since the last eruption over four centuries ago. With around 500,000 people living nearby, scientists from the Istituto Nazionale di Geofisica e Vulcanologia (INGV-OV) have intensified their monitoring efforts to analyze the seismic sequences occurring from 2021 to 2024.
Notably, the geological behavior observed during this period features sequences of earthquakes with inter-event times so brief they are often difficult to discern, categorized as burst-like swarms. These swarms are positioning the caldera’s activity pattern as deeply concerning, particularly with increased uplift and gas emissions translating to heightened volcanic risk.
The recent seismic data indicates not just sporadic activity but rather sustained and repeated swarm events, which are about 90% located around the central areas, particularly near Pozzuoli and the Solfatara-Pisciarelli hydrothermal system. The mounting evidence suggests these tectonic activities are tied closely to hydrothermal dynamics within the caldera.
The study emphasizes the correlation between the burst-like swarms and significant hydrothermal fluid pressure fluctuations, which may serve as precursors to phreatic explosions. This relationship is underlined by the increasing gas emissions reported, reaching high levels of carbon dioxide, akin to those of active, persistent volcanic systems.
The research draws parallels with other volcanic systems, positing the burst-like behavior is likely indicative of underlying geological pressures resulting from magma and fluid movements beneath the Earth's surface. Specifically, the phenomenon has been noted previously at sites such as Mammoth Mountain and White Island, where similar patterns of activity were witnessed prior to eruptions.
Concisely, the recurring nature of these burst-like swarms escalates the urgency for monitoring, especially as the patterns of seismicity continue to evolve sharply since 2021. Further insights from the study reveal strong correlations between earthquake occurrences and the existing geodetic anomalies detected within the caldera.
Measuring significant ground deformation has been instrumental for scientists to track the augments of these seismic events and propose theories about their origins. Historical data reflects periods of unrest spanning centuries, underscoring continuing shifts within this dynamic volcanic system.
Bearing new data gathered until May 2024, researchers note the association between seismic sequences and the geological processes occurring beneath Campi Flegrei remains deeply interconnected. The uplift observed at the central sector of the caldera reflects underlying crustal movements which continue to be exacerbated by increasing thermal activity and fluid migration paths.
This research aims to frame these intense geological activities within the broader discourse about urban risk areas subject to volcanic hazards. Understanding strain patterns ensures the preparedness of both local governance and scientific bodies to undertake timely evaluations and protective measures for the communities residing close to Campi Flegrei.
With future research anticipated to expand upon these findings, this work contributes significantly to the knowledge base required to develop efficient monitoring protocols for volcanic activity, assisting communities at risk of geological violence.