| Abstrakt: |
Abstract: It is well known that the vertical gradient of gravity measured on the Earth’s surface depends strongly on nearby topographical shapes. We simply inverted the problem and posed the question whether a zero vertical gradient can be observed using relative gravity meters and the classical tower method of measurement in appropriate terrain conditions. Extensively using the model of a vertical cone to simulate the real in-field conditions, we have found that reversed-cone-shaped topographic depressions represent the most perspective forms, which can contribute to extremely small values of the resulting vertical gradient. In one such form, namely a karstic sinkhole, we measured the value of -0.071 mGal/m (10-5 s-2). In addition, we successfully modeled this value using a detailed local digital elevation model. We thus conclude that zero vertical gradient of gravity should be observable by common means, also on the Earth’s surface, and not only underground within very dense rocks as some ores can be. Once this is verified it could represent a contribution to the theory of the Earth’s gravity field and its geophysical as well as geodetic applications. |
