There are transportable geodetic instruments used for cooperative research. Gravity measurements on the ground are effective to study crustal deformation and mass redistribution since they give information about density of underground layer and the distance from the Earth's center of gravity. Relative and absolute gravimeters are used for this purpose and original absolute gravimeters were developed at Mizusawa Astrogeodynamics Observatory. GPS (Global Positioning System), on the other hand, can measure distances between receivers with an accuracy of cm for ranges up to several hundred km by using radio waves emitted from GPS satellites.
GPS receiver (Trimble SSi) and antenna.
LaCoste & Romberg and Scintrex gravimeters.
Absolute gravimeter No. 2.
Absolute gravimeter No. 3.
