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Summary of Proposal GEO1119

TitleUlaanbaatar region deformation monitoring using TerraSAR-X interferometry
Investigator Pinel-Puysségur, Béatrice - CEA/DAM, DASE
Team Member
Dr Loreaux, Philippe - CEA/DAM, DASE
Dr Pinel-Puysségur, Béatrice - CEA/DAM, DASE
Dr Sèbe, Olivier - CEA/DAM, DASE
Dr Munkhuu, Ulziibat - RESEARCH CENTRE OF ASTRONOMY AND GEOPHYSICS OF THE MONGOLIAN ACADEMY OF SCIENCES, N/A
Dr Bollinger, Laurent - CEA/DAM, DASE
Dr Schlupp, Antoine - University of Strasbourg, EOST
Dr Ferry, Matthieu - CENTRO DE GEOFISICA DE EVORA, N/A
Mr Quin, Guillaume - CEA/DAM, DASE
SummaryWe propose to study deformation on Ulaanbaatar city as well as near Emeelt and Hustai active faults using TerraSAR-X SAR interferometry. As the expected deformation is very small (smaller than 1cm/y along line of sight), X band interferometry is particularly suited to this study. Vegetation in Ulaanbaatar region is relatively scarce thus temporal decorrelation should be limited except during snow season. In case of high temporal decorrelation, PS processing can be used to produce deformation maps on stable scatterers. The time series will be computed on two areas. The first area includes west of Ulaanbaatar city and Emeelt fault. The second area covers the northeastern edge of the Hustai fault, close to the capital. As no precise data is currently available on the deformation rate and direction, it may be very small and justifies our need of both ascending and descending tracks. To deal with the very small deformation we wish to measure, we need to correct at best the sources of signal different from deformation. Correction of orbital and topographic effects will benefit from TerraSAR-X accurate orbital data and TanDEM-X DEM. Tropospheric effects will be mitigated using our own codes based on meteorological models and tropospheric delay simulation. Using TanDEM-X products, two accurate DEM will be computed directly in radar geometry both in ascending and descending modes. These DEM will be used to compensate topography in the TerraSAR-X interferograms for optimal topography compensation. It will also enhance the precision of location for better projection in geographic coordinates, as well as the mitigation of tropospheric effects correlated to topography. At last, it can be used directly for morpho-tectonic interpretation. It may happen that the deformation is under the detection threshold of this InSAR study. However, this will give information on the upper bound of deformation. To do so, an objective of this study is to determine the deformation detection threshold with a given SAR time series, by evaluating the amplitude of the different signals that could hinder the deformation signal: tropospheric delay, orbital and topographic residuals and phase noise due to decorrelation. If interferograms are sufficiently coherent over more than a year, the project could be continued with acquisitions on a longer time period to enhance the detection of very slow deformation. The deformation field measurement will help constrain the maximum amount of transient slip accommodated along the fault as well as the energy released and the static stress variations. Deliverables will be: LOS deformation map on Ulaanbaatar region in ascending and descending mode or upper bound of deformation. DEM at Stripmap resolution. Data will be funded by CEA. Data requirements : On area n°1 (Emeelt Fault and Ulaanbaatar): -8 Stripmap images in ascending mode, centre (N47.94°,106.77°E), 30km x 50km: 4 acquired between June and September 2011 every 22 or 33 days, 4 acquired between June and September 2012 every 22 or 33 days. -8 Stripmap images in descending mode, centre (N47.82°,106.89°E), 30km x 50km: 4 acquired between June and September 2011 every 22 or 33 days, 4 acquired between June and September 2012 every 22 or 33 days. -2 TanDEM-X images acquired at the same time as one of the Stripmap images (one in ascending mode, the other in descending mode) On area n°2 (Hustai Fault): -8 Stripmap images in ascending mode, centre (N47.84°,106.43°E), 30km x 50km: 4 acquired between June and September 2011 every 22 or 33 days, 4 acquired between June and September 2012 every 22 or 33 days. -8 Stripmap images in descending mode, centre (N47.90°,106.53°E), 30km x 50km: 4 acquired between June and September 2011 every 22 or 33 days, 4 acquired between June and September 2012 every 22 or 33 days. -2 TanDEM-X images acquired at the same time as one of the Stripmap images (one in ascending mode, the other in descending mode)

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