Identification of Land Subsidence in Semarang Area Using Gravity Method

Abstract

Gravity data processed with Surfer software and Microsoft Excel using gravity corrections, spectrum analysis, and separation of residual and regional anomalies, can then be identified which areas are vulnerable to surface deformation such as Semarang City. The results obtained several areas that have the threat of deformation and disasters due to geology, namely in the northeast and southwest of the Semarang area marked by negative green to blue anomalies including Gajah Mungkur, Tugu Muda, Tanah Mas, and Gayamsari areas have negative anomalies, so they are identified as areas with thick sedimentary layers which are one of the causes of surface deformation. In the southeast to northwest of Semarang, Candi Sari, Simpang Lima, Tugu Mas, and Tanjung Mas, marked by yellow to reddish colors, are areas that have positive anomalies, so they are identified as areas that are quite safe in terms of deformation characterized by thin sediment layers.