POTENTIAL OF TANDEM MISSION FOR DETECTING AND MONITORING SMALL TERRAIN MOVEMENTS WITH SAR INTERFEROMETRY (TANDEM PROJECT AOT.F303)

submitted to :  3rd ERS Symposium, Florence, Italy, 18 - 21 March 1997.


Claudie CARNEC (1), Christophe DELACOURT (2), B‚n‚dicte FRUNEAU (3),
Christine KING (1), Jean-Philippe AVOUAC (4), Jos‚ ACHACHE (1)

(1) BRGM, Research, Geophysics and Geological Imagery Division, Ave. de Concyr, B.P.6009, 45060 
Orl‚ans Cedex 2, France ; Phone (33) 2.38 64 30 91 ; fax (33) 2.38 64 31 64 ; e-mail : 
c.carnec@brgm.fr
(2) IPGP, B.P.89, 4 Place Jussieu, 75252 Paris C‚dex 5, France ; e-mail : delac@ipgp.jussieu.fr
(3) Universit‚ de Marne La Vall‚e, LPMG/CESAM, 2 rue de La Butte Verte, 93166 Noisy Le Grand 
C‚dex ; e-mail : fruneau@ipgp.jussieu.fr
(4) CEA, LDG, B.P. 12, 91680 BruyŠre Le Chƒtel, e-mail : avouac@ldg.bruyeres.cea.fr

Oral presentation

keywords : Differential SAR interferometry, land subsidence, underground mining and 
seismic activity, validation, modelisation.

ABSTRACT

Differential SAR interferometry can be considered as unique tool to get surface deformation 
measurements occured on large areas (say 100 100 kilometers), with a dense grid and a few 
millimeters accuracy.

The TANDEM project AOT.F303 intends to identify and demonstrate the interferometric 
capability of the TANDEM mission in the Natural Risks problematic.  It concerns two areas 
of interest : landslides in steep relief and land subsidence in an industrial context.  The 
TANDEM mission should first offer the opportunity of detecting local movements on 
couples acquired one day apart, for which displacements are too high to be observed on 
standard orbital cycles of 35 days (i.e. landslides).  Furthermore, it should offer a regular 
temporal sequence of phenomena of lower amplitude, but spatially moving in time (i.e. 
subsidence).

The possibilities to measure land subsidence by means of SAR interferometry have been 
investigated in the southern part of France.  The preliminary results obtained on this test site 
were based on 35 days repeated ERS-1 passes [Carnec et al., 1996].  The use of image pairs 
taken 1, 3 or 35 days apart, combined with a Digital Elevation Model (DEM), showed the 
possibility of making a map of the topometrical deformation that affected the site between 
the dates of the successive images, and without needing any artificial targets.  Mapping of the 
ground movements and their corresponding fringe patterns has made it possible to extract the 
movement characteristics.  The existing monitoring and surveillance systems in the field, 
such as the benchmark network, further enable the verification of the interferometric results 
through direct comparison of the data.  The study has been carried out by taking the seismic 
activity of the area into account and assessing the influence on ground movements.  Finally, 
the interferometric results are optimized through a kinematic approach to the phenomenology 
using the temporal series of interferograms and through modelling the active movements.

Carnec, C., Massonnet, D., King, C., 1996, Two examples of the use of SAR interferometry on 
displacement fields of small spatial extent, GRL, vol. 23, no. 24, 3579-3582.

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, atmospheric chemistry