Between September 30 and October 22, 2009, the Istituto Nazionale di Geofisica e Vulcanologia (INGV) recorded a seismic sequence of modest magnitude in Central Italy, in an area of the province of Frosinone. The most significant and intense seismic activity occurred on the night between October 7 and 8, with two events of local magnitude (ML) measuring 3.6 and 3.4.
During the first 23 days of this sequence (from September 30 to October 22), a total of 1075 seismic events were recorded, all with a magnitude lower than 3.6. Previously, in May and June of 2009, another seismic sequence had occurred in a small area approximately 15 kilometers northwest of the municipality of Campoli Appennino, still in the province of Frosinone. This sequence was characterized by 64 events with a local magnitude not exceeding 2.7.
Considering the proximity of this area to the one involved in the seismic sequence of L'Aquila in 2009 with a Mw=6.3, the INGV decided to temporarily install 5 seismic stations from the Mobile Seismic Network. This decision aimed to integrate the Italian Seismic Network (https://doi.org/10.13127/SD/X0FXNH7QFY ) throughout the entire central Italy region.