Combined Use of a Superconducting Gravimeter and Scintrex Gravimeters for Hydrological Correction of Precise Gravity Measurements: A Superhybrid Gravimetry

A variant of hybrid gravimetry using both a superconducting gravimeter and Scintrex gravimeters is proposed. One of the main factors limiting the accuracy of time lapse gravity measurements is the instrumental drift of spring-type gravimeters. Running the Scintrex CG-5 gravimeter in the nighttime on the same pier as the superconducting gravimeter allows us to model the long-term behavior of the former and to remove efficiently the effect of irregular drift on measured gravity. Initial tests performed at Ishigakijima, Japan, proved that accuracy of a few μGal level can be achieved with this method. This will help us precisely correct for the effect of underground water on superconducting gravimeters with 2-dimensional local gravity survey.