Modeling response Time Lapse Microgravity Vertical Gradient (TLMVG) anomaly due to fluid volume changes of sub surface and its implementation in Kota Lama Semarang

Abstract

Abstract Modeling of time lapse microgravity anomaly have done. The modelling was done with two ways are first gravimetri position on the earth’s surface, and second position at a height of 25 cm from it. The first model shows for 30 % rock porosity than any change in groundwater within depth 1 meter causes gravity change 12,579 μGal. The second model show that reduction of groundwater wil reduce time lapse microgravity vertical gradient (TLMVG) anomaly. Reduction of groundwater will provide TLMVG negative value (-) and reverse groundwater give positive value (+). It was concluded that in the Kota Lama during the range of March to September there was no subsidence, but there was a decrease in groundwater level of 1.449 m