The borehole geophone consists of 2 horizontal receiver elements and a vertical one. The borehole geophone is pneumatically clamped to the borehole wall by means of a robust air bladder. A magnetic compass shows azimutal deviation to North. Typical applications are VSP surveys, crosshole measurements and shear wave tomography.
Alternatively, the borehole geophone BGK7 consists of 6 horizontal geophones (30 degree angle) and one vertical geophone.