Geophone

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This article is about the electronic seismic recording device. For the percussion instrument, see geophone (percussion instrument).

A geophone is a device which converts ground movement (displacement) into voltage, which may be recorded at a recording station. The deviation of this measured voltage from the base line is called the seismic response and is analysed for structure of the earth.

Geophones can be both digital and analog but recently the preference has been towards digital.

Analog geophones are very sensitive devices which can respond to very distant tremors. These small signals can be drowned by larger signals from local sources. It is possible though to recover the small signals caused by large but distant events by correlating signals from several geophones deployed in an array. Signals which are registered only at one or few geophones can be attributed to small, local events and thus discarded. It can be assumed that small signals that register uniformly at all geophones in an array can be attributed to a distant and therefore significant event.

Conversely, some applications of geophones are interested only in very local events. A notable example is in the application of Remote Ground Sensors (RGS) incorporated in Unattended Ground Sensor (UGS) Systems. In such an application there is an area of interest which when penetrated a system operator is to be informed, perhaps by an alert which could be accompanied by supporting photographic data