The superconducting (or cryogenic) gravimeter (SG) is based on the levitation of a superconducting sphere in a stable magnetic field created by a current in superconducting coils. Depending on frequency, the SG is capable of detecting gravity variations as small as 10-12 of the normal gravity. Because of its high sensitivity and very high temporal stability, the SG is eminently suitable for the study of geodynamical phenomena through their gravity signatures.
The SG of the Finnish Geodetic Institute, GWR T020 has operated continuously at the Metsähovi fundamental station since August 1994, altogether over 18 years. The instrument is the oldest working SG installation in the world without renovation.