Structure Interpretation Using Gravity Spectral Analysis and Derivative Method in Grindulu Fault, Pacitan, East Java

The Grindulu Fault is a one of the fault that lies alongside the Pacitan Regency, East Java. This fault is a land geological structure that is potential to be the source of earthquake disaster. The structure interpretation is carried out using gravity data by performing spectrum analysis and derivative methods to get a better understanding of the Grindulu Fault. We used gravity data from GGMplus. Spectrum analysis is performed by using Fourier transform to the bouguer anomaly. This Spectral Analysis generates a depth estimation of Grindulu Fault Zone anomaly source. Analysis of derivative methods provides information regarding the location of the fault anomaly source and information about the type of fault. Based on the result of spectral analysis, Grindulu Fault anomaly source is estimated to be at the upper limit of 160 meters and the lower limit up to 2897 meters. The Grindulu fault is interpreted to be segmented into at least 7 parts which is consisted of normal and reverse fault segmentations.