The Collalto seismic network (Treviso, Italy)

CURRENT SCIENTIFIC STAFF: Enrico Priolo^1,2, Maria Adelaide Romano², Marco Romanelli², Denis Sandron², Mariangela Guidarelli², Marco Garbin²

PAST COLLABORATORS: Milton Plasencia², Paolo Bernardi², Paolo Marotta²

¹Responsible Scientist
²Centro Ricerche Sismologiche, Istituto Nazionale di Oceanografia e Geofisica Sperimentale, Cussignacco (UD) e Sgonico (TS)

The Collato permanent network aims at monitoring the gas storage activity performed by Edison Stoccaggio s.p.a. in the underground natural reservoir named "Collalto stoccaggio", located in the Veneto Region near the town of Susegana (Treviso). The network is registered with FDSN with code EV. Since this network aims at recording both the natural seismicity and the induced seismicity, it has been designed with features of high sensitivity, high dynamics and wide frequency range.

This network is operating since January 1st, 2012. Continuous waveforms can be freely downloaded through this site.

The network consists of 10 sites, specifically built-up for the purpose (Fig. 1). However, the monitoring system acquires some other stations of the North-Eastern Italy Broad-Band and Friuli and Veneto Short-Period permanent networks managed by OGS (network codes NI and FV, respectively). All the EV sites host the seismometric sensors within boreholes, at dephts ranging from 5m to 155m.

Figure 1. Maps of the Collalto seismic network. Left: general overview; right: detail of the area. Symbols denote: T=20s or 30s seismometer (light blue triangles); T=20s or 30s seismometer + accelerometer (yellow triangles); T=120s seismometer + accelerometer (red triangle); short-period seismometer of the FV network (blue square).

Each station is equipped with a digital acquisition unit, a seismometric sensor deployed at depth, optionally (i.e at 5 sites) an accelerometric sensor deployed at surface, an autonomous energy supply (photovoltaic panels, in most cases) and electric batteries, a telecommunication system and Global Positioning System (GPS) antenna for precise time synchronization.

The seismological instrumentation is:

24-bit digital acquisition units Guralp mod. CMG-DM24, with either 3- or 6-channels;
borehole seismometric sensors either Guralp SP1-BH (with T=30s) or Nanometrics Trillium Compact PH (with T=20s), but for site ED06 which is equipped with a Nanometrics Trillium Compact with T=120s;
accelerometric sensors Guralp mod. CMG-5TC at 5 sites.

The seismometric/accelerometric sensors have the frequency upper-band limit set at 100Hz. The sampling frequency of the acqusition system is set at 200Hz. All the stations are connected to the CRS acquisition centers located in Udine and Trieste by a mobile phone connection (with UMTS standard). The data are continuously acquired and stored by a ringserver (free software distributed by IRIS and including a ring buffer and a SeedLink server). The processing system is based on the BRTT Antelope system.

More information can be found at the Collalto network web site.