Geoscope has been the first worldwide network to install digital seismic stations with very broad band force balanced Streckeisen STS-1 seismometers. Since 2009, new Metrozet E300 electronics are installed to replace old feedback boxes.
Système "Warpless Base Plate" (Holcomb & Hutt, 1992)
Since the end of STS-1 production, new Geoscope stations are installed with STS-2 seismometers, more compact and easier to install but not as good as STS-1.
Système "CasSis" inspired by the "Stuttgart shielding"
The seismometer is placed under a cooking pot bolted on a granite plate with a rubber gasket. This system reduces significantly, on the vertical component, long period noise due to pressure variations.
The granite plate has a kinematic machining that allows for unique positionning. The plate is oriented using a gyrocompass. The seismometer can be replaced in place and keeps the orientation.
Geoscope stations are upgraded with Q330HR digitizers : 26 bits range for +/- 20V
Data are locally recorded and stored on Baler hard drive and on a rugged mini PC running Seiscomp software.
To complete seismic sensors, pressure and temperature sensors are installed in most Geoscope stations. Several papers have shown that recorded seismic signals could be corrected from pressure and temperature variations effects.