Power spectrum analysis and multifractal detrended fluctuation analysis of Earth’s gravity time series

The time dynamics of gravity signal measured in Sheki, a site in Azerbaijan, where mainly crust deformation processes are present, is investigated by using the power spectrum method and the multifractal detrended fluctuation analysis. Our findings point out to the presence of two main periodicities (12 hours and 24 hours) in gravity signal. The analyzed gravity signal shows also a significant multifractality that depends on the long-range correlations of the time series rather than its probability density function.