Absolute and relative gravimetric surveys of national and geodynamic networks in Venezuela

Precise absolute and relative gravimeter observations were performed in Venezuela in the fall of 1988 for the purpose of (1) establishing a station of the International Absolute Gravity Basestation Network in the Precambrian Guayana Massif; (2) stabilizing the National Venezuelan Gravity Network; (3) correcting the geodynamics gravity network along the Boconó Fault in the Venezuelan Andes to absolute level and scale, as well as for reobserving the network for the fourth time within a 10-year interval. The results provide directly observed absolute gravity values for six stations all over the country with precisions of ± 0.08 to ± 0.10 μm s^-2, an improvement of precision of the National Gravity Network to an average of ± 0.12 μm s^-2, and determination of epoch gravity values for 63 stations of the Venezuelan Andes Network with an average precision of ± 0.12 μm s^-2. Analysis of the data from all four surveys reveals strong seasonal variations and small secular gravity changes.