We present the preliminary results from the analysis of GPS time series data from Deception Island Volcano for the period December 2001 to January 2005.  The geodetic network, REGID, has been episodically surveyed during every Austral summer since 1998 to monitor the volcanic activity on the island and to determine its crustal deformation. The deformational models show a continuation of the compressive process detected in the previous years. GPS data were processed using 30 min length observational windows, providing the local horizontal deformation between and within each surveying campaign. Wavelet analysis was applied to the data in order to detect the existence of short period components. The wavelet scalegram of the data reveals the presence of seasonal fluctuations that are not detectable with the usual 24 hours session processing approach. Their sources are still not well determined, which motivates the study of other geophysical phenomena that can affect the data.