The Western Crete geodetic infrastructure: Long-range power-law correlations in GPS time series using Detrended Fluctuation Analysis Original Research Article

The Global Positioning System makes it possible, nowadays, to measure crustal displacements with unprecedented accuracy. These measurements can improve our understanding of the spatio-temporal evolution of motion along tectonic plate boundaries, as well as deepen our comprehension for the nature of earthquake fault behavior and earthquake cycle. The Hellenic subduction zone and the earthquake-prone Crete, with large crustal motions of 3–4 cm/yr, may provide such a natural laboratory for this type of investigation. In this work, we examine the statistical structure and behavior of time series, as produced by permanent GPS sites, established on the islands of Crete and Gavdos.At first, we investigate the crustal motion based on daily displacements as monitored by a regional GPS network, established on either sides of faults, in Gavdos and Crete. Secondly, we reconstruct the missing data in the time series of two GPS stations, which contain the longest observations, by selecting an appropriate autoregressive stochastic model. This is accomplished by representing the state-space behavior of the signal using a Kalman filter. Finally, the Detrended Fluctuation Analysis has been applied on the residuals for the North and East components of the GPS displacements. In conclusion, there seems to exist strong evidence, at least for the period of measurements of 7.5 years, that both investigated stations show similar statistical behavior in the form of power law and exhibit the same (∼0.9–1.0) long-range correlation.