Simple design to estimate time-lapse microgravity response due to shallow subsurface density redistribution caused by land subsidence

Abstract

A simple design for modeling shallow subsurface density redistribution due to land subsidence is designed to obtain the time-lapse microgravity response. The subsurface model at each point of gravity observation is represented by a rectangular prism. A numerical example of computational modeling is performed to estimate the effect of land subsidence to the data of a time-lapse microgravity. Simple numerical simulations with an initial model that have flat topography, homogeneous density, and homogeneous compaction thickness are carried out in variations of geological and hydrological information that are often found in a study area. Additional algorithms to accommodate information on topographic variations, density variations, and compaction thickness variations in the horizontal direction also shown with illustration. Field data application for this study utilize rough estimation of the geology and the land subsidence rate in Bandung Basin. The estimation results with numerical simulations give time-lapse microgravity anomaly 0.78 to 28.61 μGal/m and field data application give an anomaly up to 10 μGal.