The combined use of InSAR and GPS data for deformation studies in the Vrancea area in Romania
Wouter Van der Wal(1) and Andre Van der Hoeven(1)
DEOS - TU Delft,
2629 HS Delft,
We present the analysis of long-term deformation in the Vrancea area in
Romania using SAR interferometry. The area is assumed to be a
conjunction of 4 tectonic blocks which lie on the edge of the Eurasian
plate. Several GPS campaigns have been carried out by, amongst others,
the University of Karlsruhe and Delft Institute for Earth Oriented Space
Research (DEOS) to reveal the motion of the blocks. In horizontal
direction relative motion amounts to 5 or 6 millimeters per year, and in
vertical direction a few millimeter per year is expected. Due to the
nature of the GPS measurements the spatial resolution is low, and
deformation in the vertical direction can not be determined very
accurately. These aspects might be improved by SAR interferometry.
Deformations at sub-centimeter level require the use of long-term
interferometry, therefore ERS SAR images have been obtained for part of
the Vrancea area in the period 1992-1998. The images are processed to
form 28 interferograms, with perpendicular baselines smaller than 100 m.
For a vegetated area normally it becomes impossible to retrieve
deformation after 1 year with interferometry, therefore statistical
methods are employed to determine relative deformation on a pixel basis.
GPS measurements can serve as a reference to these results and the
interferometric results can be used to interpolate deformations between
the GPS points. By combining both data sets also the temporal resolution
of the deformation can be improved.
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,