The invention concerns a measuring instrument of a combined seismic sensor system, which is able to measure 9 components of seismic motion, i.e. 3 orthogonal translation components, 3 components of rotation around orthogonal axes and 3 components of deflection at a given measurement point. The system contains a rigid, undeformable skeleton, horizontal and vertical seismic sensors and optical dilatometers containing at least one laser source, at least 4 laser interferometers and at least 4 corner reflectors.
The invention also includes a method of seismic measurement using that instrument. The instrument is suitable for measuring wave fields generated both by anthropogenic sources (query blasts, rotation motion generator) and by natural sources (e.g. local earthquakes, mine bumps etc.).
Optomechanical sensor system for ground motion measurement undergoes laboratory tests and it has not been deployed in the field yet.