Repeat gravity observation using CG5 relative gravimeter since 2014 measurements of A10 absolute gravimeter in Bandung and Blora, Indonesia

Abstract Since 2014 micro-gravity measurements using portable absolute gravimeter A10 and relative gravimeter Scintrex CG-5 at Bandung and Blora, we continue to monitor gravity value at several cities in Java Island, Indonesia. Repeat observation from 2014 to 2024 activities conducted by team from FTTM Geophysics Exploration Laboratory. From this activities, several studies (such as: field camp geophysics, undergraduate final projects, and magister thesis) that using gravity data can be conducted. The studies mainly used to monitor hidrology variation and structural modeling in the subsurface. Repeat gravity observation during ten years (2014 to 2024) cover several cities such as: Bandung, Kebumen, Yogyakarta, Klaten, Blora, Ngawi, Madiun, and Ponorogo. Next study in several cities can be proposed to repeat the observation in several area such as: Nganjuk, Magetan, Pacitan, Sragen, Karanganyar, Wates, Purworejo, Banyumas, Cilacap, Banjar, Ciamis, and Garut. Time-lapse microgravity studies already cover the area in the several vilages in Blora, three Kecamatan of Kota Madiun, several Kecamatan of Ngawi (baseline-survey), and Bandung (since 2010 to 2021). From this work, several gravity values from reference benchmark (BM) shows small changes with standard deviation less then 20 microGal (16 refference stations), while 8 stations provide standard deviation in the range 20 to 82 microGal, and 2 other stations shows higher standard deviation up to 126 microGal.