3.04 – Superconducting Gravimetry

The superconducting gravimeter (SG) uses magnetic levitation as a stable gravity spring and is the default relative instrument for observatory gravity. SGs have high precision (~ 0.01 μGal), exceptional calibration stability (~ 0.01%), low drift (few μGal per year), and record at periods from 1 s to years. The newest iGrav SG is transportable in a small SUV, requires no liquid helium, has integrated electronics, and is easy to set up. We review instrument design, reduction and data processing, and many applications: seismic modes; tides and nutations; large- and small-scale atmospheric, oceanic, and hydrologic loading; volcanology; coseismic signals; and time-variable gravity exploration.