Gravity control network at airports in nigeria

Abstract

A network of gravity of control bases located at most of the airports and airfields in Nigeria has been established as a means of controlling future gravimetric studies in Nigeriaand of integrating existing gravity surveys into a unified whole for the purpose of producing gravity anomaly maps for the country. The network will also provide a means of checking and adjusting gravimeter calibration differences to a common standard. The LaCoste and Romberg gravimeters, models G446, G464 and G468, used for the observations were transported between the base stations by means of a six-seater fixed-wing aircraft. The scale adopted of the network was the same as that of gravimeter G464 to which the other two meters were referenced. The absolute gravity values observed ranged from 978184.882 ± 0.014 mGal at Nguru to 977844.379 ± 0.020 mGal at Jos, yielding a gravity range of 340.503 mGal. The accuracy of the individual absolute gravity value is better than 0.030 mGal using a datum value of 978120.933 mGal for site 103401 estlished at the Kano International Airport. The 34 observation sites are illustrated with sufficient detail to permit reoccupation within 0.50 m to 1.0 m.