Exploring The Detailed Structure Of The Local Earth’s Gravity Field Using Fractal And Fourier Power Spectrum Techniques

As one of the world’s oldest continents, Australia has experienced a complicated geological history and thus has a distinctive landscape and an extensively weathered topography. As such, the gravity field of Australia behaves differently to that in other countries. This paper investigates the features of the Australian gravity field. The methods used are a simple statistical comparison, Fourier power spectrum analysis and the Hurst lkctal technique. Three test gravity and height profiles, which represent extreme features of the Australian gravity field (ie the Hamersley Ranges, Central Australia and The Snowy Mountains), have been selected. It is shown that the gravity field of Australia is not always correlated with the terrain and the topography often contains longer wavelength features than the gravity anomalies. It is demonstrated that the simple statistical analysis and Fourier power spectral methods are the most informative tools for measuring the smoothness of the gravity field. It is revealed that none of the free-air, Bouguer or topographic-isostatic gravity anomalies is consistently the smoothest type in Australia. Sometimes, the Bouguer anomaly is more variable than the free-air anomaly and thus should not necessarily be used for gravity field gridding in Australia.