12/10/2021 ML 2.5 seismic event near Lodi

At 23:18:21 UTC on 11/10/2021 (01:18:21 local time on 12/10/2021) an earthquake occurred in the municipality of Tavazzano con Villavesco in the province of Lodi. The earthquake was recorded by the Cornegliano Laudense Seismic Network (RSCL), as well as by the National Seismic Network (RSN) and Regional Seismic Network of Northwest Italy (RSNI) managed by INGV and the University of Genoa, respectively.

Regarding the monitoring system of the RSCL we report that the automatic detection system worked correctly and the event was manually relocated by seismologists. The estimated parameters for the event are shown in Table 1 and Figure 1. Figure 2 shows the seismograms recorded by some of the RSCL stations.
It should be noted that since the two monitoring systems have different purposes - the RSN and RSNI networks are used for regional and national scale monitoring, respectively; the RSC network is used for local scale monitoring in the area of the Cornegliano Laudense underground gas storage (UGS) facility - the parameters estimated by the two systems may differ, although not significantly.

According to the RSCL analysis, the reported event occurred at 01:18:21 (local time) at a depth of 30.5 km and has an estimated magnitude of ML 2.5. The event occurred in an area between the rivers Ticino and Adda, where the seismicity is usually deep and weak. Recent re-analysis of data collected by several monitoring networks from 1985 to 2019 in a study aimed at defining the background seismicity of the area around the Cornegliano Laudense site (Schibuola et al., 2021) recognize the presence of some earthquakes of ML less than 3.5 at similar depths.

Considering the depth of the event, the overall pattern of the past seismicity, and the information on the UGS activities provided by the Licensee, there is no evidence to establish any connection between the occurred earthquake and the UGS activities at Cornegliano Laudense.

Seismological Analysts: Enrico Priolo, Mariangela Guidarelli, Maria Adelaide Romano, and Peter Klin

The Responsible of the Cornegliano Laudense Seismic Network (RSCL): Enrico Priolo

References

  • Peruzza, L., Schibuola, A., Romano, M. A., Garbin, M., Guidarelli, M., Sandron, D., and Priolo, E.: A revised image of the instrumental seismicity in the Lodi area (Po Plain, Italy), Solid Earth, 12, 2021–2039, https://doi.org/10.5194/se-12-2021-2021, 2021

Figura 1. Localizzazione dell’evento ML 2.5 del 12/10/2021 ore 01:18:21 (ora locale). Nelle figure si notano anche le posizioni delle stazioni sismiche utilizzate dal sistema di monitoraggio.

Figure 1. Location of the ML 2.5 event of 12/10/2021, 01:18:21 (local time). In the figure the seismic stations used for earthquake location are also plotted.

Figura 2. Sismogrammi dell’evento del 12/10/2021 ore 01:18:21 (ora locale) registrati dalle stazioni della RSCL.

Figure 2. Waveforms for the 12/10/2021, 01:18:21 (local time) event recorded by the instruments of the RSCL.

Sgonico, 13 ottobre 2021

Tabella 1.

Table 1 – Location obtained by the Seismic Network of Cornegliano Laudense system (RSCL), manually revised.

Tabella 2.

Table 2 – able 2. Locations obtained by the monitoring system of the North-West Italy Seismic Network (Genova) and by the National Seismic Network (INGV).