The gravimeter has been used both by the Physics community (measurements of the Gravitational Constant), and by the Geophysics community (measurements of the rate of growth of mountain ranges and ice-sheets, changes in global sea level and subsurface water-table, long-wavelength subsidence, and regional volcanic and seismic studies). Theoretical investigations include comparisons between GPS and absolute-g estimates of elevation change, and estimates of the performance of new tyes of gravimeter for land and marine use. An approximate breakdown of proportional use is shown in the pie-chart below.

Not included above are test measurements made between new and transient FG5 gravimeters at the Table Mountain Observatory, Boulder. Maintenance at Micro-g is usually only a few days, but occasionally a week-long service is involved. As of mid 1998 the total number of field observation days was 240 .

Narrative descriptions of NSF supported Absolute-g investigations 1994-7.

YEAR ONE
October - December 94
Acceptance testing and debug.
March - April 95 (tectonics, seismic hazard)
LA Basin experiment; Hudnut et al at CALTECH; 5 sites surveyed (Kresge, Caltech, JPL Aries Pad, Chilao, Mt. Wilson). Experiment was to establish gravity control at GPS sites, in order to correlate gravity and vertical elevation changes associated with possible creep on blind thrusts.
June 95 (Fundamental physical constants)
Luddington, Michigan (Niebauer, Colorado School of Mines); Newtonian gravitational constant determination by using the mass of water stored at a dam. Results were ambiguous due to high seismic noise levels in the structure.
June-July 95 (system support, metrology)
IUGG absolute gravimeter intercomparison (Sasagawa, TMGO). FG5 systems agreed at the O.9 µGal level (Robertson et al, 1996)
August-September 95 (tectonics, global change, mantle rheology)
Fennoscandian uplift experiment (NOAA); 16 sites surveyed. Second epoch measurements of post-glacial rebound

YEAR TWO (Fundamental physical constants)
October-November 95 Newtonian gravitational constant determination at TMGO
(Faller, CU Boulder); Moving mass method for G value determination, laboratory test. Tests indicate 2% disagreement in the value of the Newtonian constant of gravitation.
March - April 96 (tectonics, global sea level)
Mexican Subduction experiment (VanDam, Larson and Bilham); 9 sites surveyed (Acapulco, Chamela, Chilipacingo, Guadalajara, Manzanillo, Mexico City, Puerto Vallarta, Pinotepa, Taxco) ; first epoch measurements
May - June 96 (rift tectonics)
Nevada basin and range experiment (Harry, Univ. Alabama); 7 sites surveyed; (Berlin, Calavada Summit, Candelaria, Gote Flat, Mono Lake, CA, Sonora Pass, Virginia City) ; first epoch measurements
July 96 (visco-elastic rebound, global change)
Canadian shield uplift experiment (funded by NOAA); 3 sites surveyed; (Churchill, Pinawa, Flin-Flon) post-glacial rebound experiment; use of an additional gravimeter added confidence to validity of observed trend

YEAR THREE
September - October 96 (volcanology, instrument development, crustal deformation)
UCSD experiment (Zumberge) with FG5/102; 6 sites surveyed (Quincy, Mammoth Lakes, Pasadena, Pinon Flat, San Diego, Monument Peak) ; extensive laboratory instrument tests; re-occupation of California stations. Initial results indicate significant gravity signals at Mammoth Lakes since the previous absolute gravity survey (1989)
November 96 - February 97 (Himalayan uplift study)
India/Nepal convergence tectonics experiment (Bilham &Larson); 11 sites surveyed, (Nepal: Nagarkot, Kathmandu sites A and B, Chaku, Kodari, Jiri, Tansen sites A and B, Siddharthanagar, Simara, Biratnagar, Bhedetar). Although funded by NSF and complementary to the study of tectonic processes targeted by the project, the absolute gravity measurements were not specifically itemized in the budget and were made possible by reducing the number of planned GPS measurements.
January - March 97 (Newtonian Gravitational constant study)
TMGO (Faller) with FG5/102; Newtonian gravitational constant determination, Phase II. Preliminary engineering test for new moving mass system.
March 97 (fundamental physics, instrument tests)
Stanford University (Chu); comparison with atomic interferometers used as absolute gravimeters. FG5 motivated a search for a systematic error in the atomic gravimeter.
May 1997 - (Newtonian Gravitational constant study)
TMGO (Faller) Newtonian gravitational constant determination, Phase III