The Terrestrial Gravity Survey Around Ibu Kota Nusantara (IKN) Area, Indonesia

Abstract The Geospatial Information Agency of Indonesia (BIG) conducted a terrestrial gravity survey around the Ibu Kota Nusantara (IKN) area, projected to be the new capital city of Indonesia. The objective of the surveys was to collect gravity data to develop a geoid model serving as the vertical reference system. The survey encompassed 164 measurement points, spaced sporadically at intervals of 2.5 km to 3 km and utilizing the CG-5 Scintrex gravimeter. Each point was surveyed for 10 minutes with a 1 Hz data interval. Accurate positioning of the points was achieved using the Global Navigation Satellite System (GNSS) with real-time kinematic (RTK) method, receiving corrections from nearby Continuously Operating Reference Station (CORS), including CBAL station located in Balikpapan City. The gravity data was processed using the Gradj and Grano subprograms of the GRAVSOFT software, referenced to the primary gravity pillar GBU025, with an absolute gravity value of 978,039.879 mGal ± 0.007 mGal. The adjustment process revealed that the standard deviation of gravity values ranged from 3.102 mGal to 4.872 mGal.