The geophysical observation network in Irpinia is growing and consolidating: the 20 km of fiber optic cable already tested has become 80, transforming the experiment into a truly new monitoring system which, among other things, also recorded the magnitude 4.0 earthquake that recently struck the province of Avellino.
The Irpinia Near Fault Observatory (INFO), the observation system for the study of seismicity in Irpinia born from the collaboration between theNational Institute of Geophysics and Volcanology (INGV) andUniversity of Naples Federico II, within the European Research Infrastructure EPOS, becomes an operational reality thanks to the PNRR-MEET Project of INGV.
For more than a year the INFO observatory has been equipped with a experimental distributed seismic sensing device (DAS) implemented in Tito Scalo (PZ) and based on 20 km of optical fiber. To date, seismic signal acquisition has been extended to an 80 km stretch of optical fiber, constituting a continuous monitoring system of the Irpinia-Lucanian fault system connecting Sant'Angelo le Fratte to Castelgrande (PZ), which is capable of "photographing" subsurface movements with extremely high precision.
“If we look at the seismicity in Irpinia over the last twenty years”, observes Giulio Selvaggi, seismologist at INGV and scientific coordinator of the MEET project, “there are few seismic events of significant magnitude. In order to study the fault system and understand the dynamics of the Earth's crust in the area, we need a magnifying glass that allows us to see the smallest earthquakes and analyze them in detail.".
Thanks to the collaboration with the companies Metis and Fastweb, The optical fiber commonly used for telecommunications is now employed as a dense network of sensors distributed along the route.
“The measurements come from a laser source that sends light pulses into the fiber,” explains Gilberto Saccorotti, seismologist at the INGV. “The passage of the seismic wave deforms the fiber and, by modifying the optical path of the pulses, allows for precise measurement of ground deformation. It's like having a seismometer installed every 10 meters, along a distance of 80 km.”
The new system, dedicated to the characterization of microseismicity in the area, has already recorded numerous low magnitude events; however, by continuously monitoring the Irpinia-Lucanian fault system, it has also been able to record the An earthquake of magnitude ML 4.0 occurred in the Montefredane (AV) area on October 25th., at a depth of about 15 km. The ground deformation caused by this event was observed along the entire 80 km of optical fiber., providing a detailed and continuous image of the propagation of seismic waves that, at the moment, is unprecedented on a national scale.
“We are facing a real new monitoring system which radically transforms the signal that we were able to detect until now with traditional seismic sensors" concludes Gaetano Feast, professor of Physics at the University of Naples Federico II. “With 80 km of cable integrated into the DAS we are able to characterize in detail also microseismicity and to make a qualitative leap in the knowledge of the processes that occur on the Irpinia fault system and of the seismic risk".
This technological leap marks a decisive advance in the ability to closely observe the genesis and dynamics of earthquakes, paving the way for new applications of fiber optics in Italian geophysics.
Useful links:
National Institute of Geophysics and Volcanology (INGV)
University of Naples Federico II
Irpinia Seismic Network - data and products
IPSES Platform for the Study of the Solid Earth
Figure: DAS recording of the magnitude 4.0 earthquake that occurred on October 25, 2025, in the province of Avellino. The colors refer to ground deformation along an 80 km stretch of fiber optic cable, extending from Sant'Angelo le Fratte to Castelgrande, in the province of Potenza. 
