Monitoring Reports

We have developed an analysis of the “San Potito e Cotignola” monitoring network (SPCSN) and its detection capabilities. This is the minimum value of magnitude that the network can detect at a given point in space depending on its geometry and density and the background noise level at each station, which in turn depends on the characteristics of the subsurface.

The following conclusions can be drawn from this:

• In general terms, the study area could present a number of objective difficulties, mainly related to the high degree of anthropization as well as a considerable sediment thickness in the region.
• Despite this situation, the PSD functions of the noise at the 10 stations of the network show that they are within the standards established by the Peterson NLNM and NHNM models.
• Background seismic noise is the factor that most affects the overall performance of the network.
• Our study suggests that ML~ 0.1 is the minimum detectable magnitude for precisely localized earthquakes.
• The network is capable of detecting events with ML~ 0.1 almost for the entire alert area, with the number of triggered stations at 33%.

The analysis of the earthquake catalog located in the surroundings of the San Potito and Cotignola storage concession from 12/17/2018 to 04/30/2023, described in this report, provided useful indications for an initial evaluation of the performance of the microseismic network installed by Solgeo Srl, as well as for the redefinition of the microseismicity detection domains.

Highlighted catalog limitations:

• lack of information on the seismic phases used for locations;
• lack of homogeneity of codes and velocity models used;
• absence of the definition of location uncertainty and details on the local magnitude estimation.

From the point of view of microseismicity, the network has objectively demonstrated a better capability of detecting microearthquakes compared to the national network, lowering the completeness magnitude by at least one degree.

This report accounts for the activity of the Structure in charge of Monitoring (SPM) at the natural gas storage concession named “SAN POTITO & COTIGNOLA STOCCAGGIO”, on behalf of Stogit S.p.a. (ex Edison Stoccaggio S.p.a.), for the period between May and July 2025.

The SPM is composed of the National Institute of Oceanography and Applied Geophysics (OGS) and the Company Geophi S.r.l.

The report is composed of the section concerning seismic monitoring, entrusted to OGS, and the section concerning the monitoring of pore pressures and induced deformations, entrusted to Geophi S.r.l.

This report accounts for the seismic monitoring activity that OGS carries out at the natural gas storage concession named “SAN POTITO & COTIGNOLA STOCCAGGIO”, on behalf of Stogit S.p.a. (ex Edison Stoccaggio S.p.a.), for the period between August and October 2025.

The monitoring activity is planned following the approval of the project to conduct overpressure storage tests, and according to the ministerial Guidelines and Directives (ILG).

Please refer to the first half-yearly report regarding:

• The legal framework and the most significant steps of the bureaucratic process;
• The characterization of the area from the point of view of geology and seismic hazard;
• The analysis of the theoretical microseismicity detection capability.