After the strong earthquake of magnitude 4.0 of 1 September, ai Campi Flegrei they were detected overall 98 SISMIof which 65 occurred during a seismic swarm. This is what emerges from the last weekly bulletin of the Vesuvian Observatory of the Ingv, relating to the period between 1 and 7 September. Phlegraean seismicity, therefore, is in slight decrease Compared to the previous week, when 116 earthquake shocks were recorded, while the lifting of the soil due to bradisism is confirmed to be stable at an average speed of 15 ± 3 mm per month. Nonetheless, during the seismic swarm, the Observatory identified a lowering of the soil of approx 2.5 cm In the military academy area: the trend stopped immediately after September 1st.
No significant variation for i Geochimic parameterswith the average temperature at Pisciarelli’s main fumarola which is confirmed by 94 ° C. Consequently, the INGV excluded significant evolutions in the short -term Flegrea area.
98 earthquake shocks detected, of which 65 during a seismic swarm
Between 1st and 7 September they were detected 98 S shocks earthquake, of maximum magnitude 4.0, 65 of which took place during a seismic swarm that began on August 31, at 14:09, and continued until 18:26 on 1 September. Overall, in the two days they were recorded 131 earthquakes in the area of Solfatara-Academia-Agnano.
As usual at the Flegrei Campi, the SISMI were rather superficialwith a depth between 0.15 km and 2.58 km. In bradisismic areas like this, in fact, seismicity is not due to the activation of fault but the lifting of the soil.
From the geochemical point of view, the heating and pressurization trends of the hydrothermal system already known are confirmed. At the same time, i carbon dioxide flows (CO2) From the ground measured in the Pisciarelli station they did not show significant variations compared to previous periods.
Stable the lifting of the soil due to bradisism
During the seismic swarm of 1 September, the Vesuvian Observatory detected a lowering of the soil of approx 2.5 cm In the area of the military academy and 1 cm in the Monte Olibano area: at this moment, however, the trend has taken up the same trend that had before the event of September 1.
During the week, therefore, the lifting of the soil due to the phenomenon of bradisism continued at a constant speed of 15 millimeters per monthstable value since the beginning of April 2025 after the rapid increase recorded between February and March 2025, when the average monthly value had reached 30 ± 5 mm/month. From January 2024, the total lifting recorded at the Rite GNSS station (Rione Terra) is approximately 32.5 cm.
The Bulletin of 9 September in summary
From the weekly bulletin on the Flegrei fields issued by the Engv-Oe on 9 September it appears:
- Seismicity: 98 earthquakes were recorded, with maximum magnitude 4.0 (recorded on September 1), of which 65 took place during a seismic swarm that began at 14:09 on 31 August and continued until 18:26 on 01 September.
- Soil lifting: bradisism continues stable at 15 ± 3 mm per month, a value that remains constant since the beginning of April.
- Geochemistry: the INGV does not signal significant variations compared to the already known trends of heating and increased flows. The average temperature recorded in the Fumarola in Pisciarelli is about 94 ° C.
