This research study is conducted in the eastern part of northern Thessaly, which is located in the middle of Greece and has a total area of 3113.834 km². This study area suffers from natural and human hazards which have gradual and rapid impacts and which as a consequence threaten the stability of civil infrastructure and moreover agricultural projects. They are related to huge groundwater withdrawal for agricultural irrigation as well as other uses, type of lithology, active normal faults which cross the study area, earthquakes, and many other minor factors. 

According to the historical seismicity, the study area is characterized as having medium to high seismicity due to the fact that the last earthquake of high magnitude (Ms = 6.1) occurred in 1941. However, according to the literature no earthquake with a magnitude greater than Mw = 4 has been observed since 1941.

Given the scientific fact that no earthquake with a magnitude greater than Mw = 4 has been observed since 1941. Furthermore the scientific demands to identify and investigate the causes of low magnitudes earthquakes which have occurred within the study area after 1941 so far. Additionally to investigate the constant and dramatic influences of groundwater withdrawal on the (objects) stabilization which are located within or on the ground; moreover the impact of other participating parameters on ground deformation such as type of lithology and soil. In addition to verifying from the ability of applying Synthetic Aperture Radio detection and ranging Interferometry (SAR Interferometry) techniques to identify ground deformation phenomena resulting from any causes within urban and non-urban areas, this research has been implemented. 

Consequently the objectives of this study are to verify the possibility of implementing SAR interferometric techniques to detect short- and long-term deformation as well as to investigate the factors that affect ground deformation within the study area. 

Three interferometric SAR techniques have been implemented using GAMMA Software (S/W): the Conventional, Stacking Interferometric, and Persistent Scatterer Interferometric (PSI) techniques. Two datasets from the Earth Resources Satellites (ERS1/2) and the Advanced Synthetic Aperture Radar Environmental Satellite (ASAR ENVISAT) of ascending and descending tracks have been used during the periods 1995–2008 and 1992–2010, respectively. 

The results were as follows: 

-         The results of three techniques within ascending and descending tracks indicate that subsidence and uplift deformations are distributed over the whole of the study area.

-          No interferometric deformation patterns have been observed within agricultural fields by implementing the interferometric stacking technique of ascending and descending tracks; however interferometric deformation patterns are confined to urban and mountain areas.

-         Interferometric deformation patterns have been observed within urban and agricultural areas through the application of conventional techniques with ascending and descending tracks by applying period of short-term.

-         The results of interferometric stacking of the descending track indicate a low distribution of patterns density in comparison with the ascending track; furthermore the number of candidate points within the descending track is smaller than the number of candidate points in the ascending track. An interpretation of this case is occurred in pairs between different seasons typically encounters stronger atmospheric effects (in particular stronger height-dependent atmospheric effects).

-         The results showed that the descending track had more difficult phases to unwrap and this may reduce the spatial coverage achieved.

-         A direct correlation has been found between the number of inteferograms and the average coherence with ascending and descending tracks within the urban area. However, an inverse correlation has been found between the number of inteferograms and the average coherence within agricultural fields.

-         A direct correlation has been found between the long perpendicular       baseline and the result for the number of interferograms. In addition a direct correlation has been found between wrapped phases and the long perpendicular baseline.

-         A significant correlation has been found between fluctuation of the groundwater level and land deformation within the ascending and descending tracks, despite the short time series data of the ascending track (1995–2006) and the long distance between boreholes and many point candidates of PSI relevant to the descending track. This may be attributable to the short distances between boreholes and many point candidates regarding the ascending track or to the large range of the time series data (1992–2010) of the descending track.

-         The results of the conventional technique point to seasonal deformation. This is attributed to the fluctuation of groundwater level, which plays an important role through its impact on ground deformation during short time periods of up to one month.

-         Differences in the ground deformation rate of the same settlements resulting from the interferometric stacking technique of two tracks, ascending and descending, may be attributed to the difference between the numbers of interferograms within each interferometric stacking result, since there were 29 items within the ascending track and 70 items within the descending track. Furthermore, there were differences between the time periods of the radar images within each track and between the locations of reference points within each track.

-         The persistent scatterer technique, through the application of spatial   correlation between the locations of candidate points and fault traces, reveals and/or indicates the possibility of the influence of fault movements on ground deformation.

-         The other main reason for deformation is the compaction of materials induced by water pumping and this is related to local deformation. This compression of materials may produce a micro-seismic magnitude (3 to 4).

-         SAR interferometry techniques successfully revealed the impact of lithology type on ground deformation through the ascending and descending tracks.

-         Many of the parameters participated together furthermore have nested impacts on ground deformation within the study area as well as it is difficult to completely isolate the influence of each single parameter individually in spite of applying statistical correlation.