The use of gravity anomaly data to estimate the depth of mohorovicic discontinuity in bali area used power spectral analysis

Abstract

Gravity is a geophysical method that can be used to measure the contrast difference in subsurface density for the interpretation of geological structures. Gravity is a non-destructive geophysical method so it is widely used in subsurface research. Bali is an area with a complex tectonic order because of its location which is part of the east Sunda arc. Bali is formed due to the subduction process of the Indo-Australian Ocean crust transition zone with Australia's continental crust to the west and the Banda arc. This study aims to estimate the depth of sediment and limits of discontinuities of the island of Bali using the method of power spectral density analysis. The data used is gravity anomaly data from TOPEX on the island of Bali. Principle method of power spectral density analysis is to analyse the phenomenon of the harmonic oscillator in nature. The data of gravity obtained will be transformed using Fourier series so as to change the time domain into the frequency domain. From the results of processing obtained if the rocks on the island of Bali is a Miocene rock with an initial body density of 2.6 gr / cm3. The depth of shallow discontinuity ranges from 519.35 m hi to 5.92 km with an average depth of 2.63 km. While the depth of discontinuities in the range of 18.30 km to 69.62 km with an average depth of 43.39 km. It is estimated that the sediments of Bali island are shallow because of the rock age of the island of Bali which is still young adrift in the geological time scale.