Seismic Sensors

The ISS supports a wide range of commercially available sensors including miniature geophones,
short period and broadband seismometers, force balance accelerometers (FBA) and piezoelectric
accelerometers.
In addition to this, ISS International manufactures a range of geophones and piezoelectric accelerometers
for borehole applications.
Geophones
Geophones manufactured by ISS International are designed to be installed in a borehole of diameter
76 mm. The sensors are cast with an integral cable of length 15 m (customised lengths
are available on request).
Type Natural Undamped Tilt Displacement Approx Usable
Name Frequency Sensitivity Angle Limit Frequency Range
[Hz] [V/m/s] [o] [mm] [Hz]
G4.5 4.5 28 2 4 3 -2000
G14HS 14 80 180 0.5 7 - 2000 Extended Low Frequency Response
Electronically enhanced sensors make use of electronic compensation to extend the range of
sensitivity below the natural frequency of the geophone element used in the sensor. This results
in a sensor with an extended range that can be installed in a small borehole, but at a cost much
lower than the equivalent natural geophone.
The 14 Hz sensor can be used with an extended low frequency response by using a capacitor in
the damping feedback. The result of extending this response is shown in the graph. Extended Low Frequency Response
Electronically enhanced sensors make use of electronic compensation to extend the range of
sensitivity below the natural frequency of the geophone element used in the sensor. This results
in a sensor with an extended range that can be installed in a small borehole, but at a cost much
lower than the equivalent natural geophone.
The 14 Hz sensor can be used with an extended low frequency response by using a capacitor in
the damping feedback. The result of extending this response is shown in the graph.