Vol.44-1 ABSTRACT1


One of the purposes of gravity survey conducted by the Geographical Survey Institute (the GSI) is to provide the standard values of gravity measurements in Japan. Recently, the accuracy of measurement has been improved using absolute gravimeters, so surveys have been executed to acquire data for precise geodetic studied as well. Especially, gravity observation is one of the few means of exploring the changes of the inner earth. By repeated observations of gravity, we can detect the temporal variation of gravity. Consequently, in order to meet the demand for a domestic gravity standardization net corresponding to the present measurement accuracy, the GSI newly established Japan Gravity Standardization Net 1996 (abbreviated to JGSN96). JGSN96 has an accuracy of 0.01 mGal1, which is one order higher than that of Japan Gravity Standardization Net 1975 (JGSN75), making it useful for detecting temporal variations and analyzing gravity anomalies in the future.