Page "Geophone" Paragraph 14

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.