Identification of the subsurface structure using gravity method in Kasihan village, Pacitan Regency

This study aims to describe the subsurface structure in Kasihan Village, Pacitan Regency, based on the rock density variations. Data was collected at 54 measurement points using Gravimeter LaCoste Romberg G-1118 and Global Positioning System (GPS) Trimble 4600 LS. The measurement result showed that the topography of the study location with an elevation of 660 - 830 masl, while the gravitational field is based on the Complete Beugeur Anomaly analysis is 266 - 302 mGal. The results showed that based on the modeling of rock density variations, the subsurface layer has three rock types. The first layer is the rock with a density of 2.4 g/cm3, interpreted as a sandy conglomerate. The second layer is the rock with a density of 2.7 g/cm3, interpreted as volcanic sandstone. The third layer is the rock with a density of 2.9 g/cm3, interpreted as an igneous rock intrusion of andesite and dacite. The model of the subsurface structure also identified a strike-slip fault in the direction of Southwest-Northeast.