Seismic swarm at Campi Flegrei raises questions but not immediate alarm, Italy

A seismic swarm consisting of approximately 64 events, with magnitudes ranging up to 4.2, has been observed since 05:06 LT on September 26, 2023, in the Campi Flegrei region, Italy.

• Campi Flegrei is a 13 km (8 miles) wide caldera that encompasses part of Naples (population 3 million) and extends to the south beneath the Gulf of Pozzuoli.
• The last eruption at this volcano, from September 29 to October 6, 1538 (VEI 3), formed the Monte Nuovo cinder cone.

According to data released by the Vesuvian Observatory of the National Institute of Geophysics and Volcanology (INGV), the earthquakes are located in the Accademia-Solfatara area (Pozzuoli) and in the Gulf of Pozzuoli.

Mauro Di Vito, Director of the INGV Vesuvian Observatory, stated that the situation is under constant monitoring. Geophysical and geochemical parameters suggest that the ongoing dynamics, including soil lifting at a speed of around 15 mm (0.6 inches) per month, show no significant changes compared to previous data. “At present, there are no elements that suggest significant evolutions of the system in the short term,” Di Vito said.

The Campi Flegrei area has a history of intense volcanic and seismic activity. Episodes of bradyseism—slow ground movement—accompanied by seismic swarms have been observed in the past, particularly during 1969-72 and 1982-84. More recently, ground uplift in the Rione Terra area reached approximately 113 cm (44 inches) by July 2023.

Seismic swarms and ground uplift may be due to the rising of gases and increased pressurization of the deep hydrothermal system. Another possibility is the injection of magma into the subsurface. Both phenomena are related to a larger, deep magma chamber beneath the Phlegraean Fields. INGV continues to measure geochemical and continuous data from both fumaroles and wells to monitor this activity.

The Department of Civil Protection is working in close contact with the Vesuvian Observatory to monitor the situation. While the probability of a volcanic eruption is considered low at this time, the observatory remains vigilant.

While the current data do not indicate immediate threats, the seismic activity in the Campi Flegrei region is a subject of utmost concern for scientists and public safety officials alike. Monitoring will continue to ensure the most accurate and up-to-date information is available for public safety and preparedness.

References:

¹ Communication from the Director of the Vesuvian Observatory, seismic swarm update at the Campi Flegrei – INGV – September 27, 2023

² The origin of the seismic swarms at the Campi Flegrei. Update. – INGV – September 9, 2023

Featured image credit: INGV