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Establishing a new gravity reference station for geophysical investigation and educational purposes: comparison with satellite gravity data in Banda Aceh city, Indonesia

Irwandi, I.; Darisma, D.; Simanjuntak, A. V. H.; Sofyan, H.; Asrillah

Inst. Angewandte Geowissenschaften

Determining the gravity reference point in the form of the absolute gravity acceleration value is necessary for education and research purposes. Department of Physics, Universitas Syiah Kuala (USK), has had the Scintrex CG-5 gravimetersince 2013 and should have had one absolute gravity point around the campus. A new gravity reference point was made at the Tugu Field (Lapangan Tugu) USK, which was derived from the gravity reference point BMKG Mata Ie with an absolute gravity value of 978102.87 mGal. First, we measured the relative difference in gravity’s value between the two points using the Scintrex CG-5 gravimeter. The difference of gravity value at the Tugu Field with BMKG Mata Ie is 23.8356 mGal smaller so that the absolute gravity value is 978079.01 mGal. The result is consistent with the geological data where the rocks around BMKG Mata Ie are metamorphic rocks that began to form in the late Jurassic, while the strata at the Tugu Field consist of young alluvium in the Holocene epoch which has a lower rock density. To verify the absolute gravity value, it is compared with the gravity value obtained from the satellite TOPEX. Data from these satellites is around 978140.15 mGal with a difference of 61.14 mGal.