Estimation of small surface displacements in the Upper Rhine Graben area from a combined analysis of PS-InSAR, levelling and GNSS data

Fuhrmann, Thomas; Cuenca, Miguel Caro; Knöpfler, Andreas; Leijen, Freek van; Mayer, Michael; Westerhaus, Malte; Hanssen, Ramon F.; Heck, Bernhard

doi:10.1093/gji/ggv328

Cited by 38 publications

(37 citation statements)

References 40 publications

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“…The fusion of LOS velocities is performed on a pixel-by-pixel basis on the interpolated grid nodes. This approach also enables other geodetic data to be incorporated if available, such as GNSS or levelling observations [61,62]. Furthermore, it is possible to fuse InSAR-derived LOS measurements from different SAR sensors and with different operating frequencies (X-band, C-band, L-band; see reference [68]).…”

Section: Multi-geometry Data Fusionmentioning

confidence: 99%

“…This is particularly applicable when a long wavelength deformation signal is the target of investigation because the relatively sparse sampling of GNSS measurements is less of an issue when the deformation signal has a long wavelength [53][54][55][56]. Furthermore, independent geodetic data can be used to solve for a full 3D motion vector by combining the data sets mathematically on a pixel-by-pixel basis [57][58][59][60][61][62].…”

Section: Introductionmentioning

confidence: 99%

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Resolving Three-Dimensional Surface Motion with InSAR: Constraints from Multi-Geometry Data Fusion

2019

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Interferometric synthetic aperture radar (InSAR) technology has been widely applied to measure Earth surface motions related to natural and anthropogenic crustal deformation phenomena. With the widespread uptake of data captured by the European Space Agency’s Sentinel-1 mission and other recently launched or planned space-borne SAR missions, the usage of the InSAR technique to detect and monitor Earth surface displacements will increase even more in the coming years. However, InSAR can only measure a one-dimensional motion along the radar line of sight (LOS), which makes interpretation and communication of InSAR measurements challenging, and can add ambiguity to the modelling process. Within this paper, we investigate the implications of the InSAR LOS geometry using simulated and observed deformation phenomena and describe a methodology for multi-geometry data fusion of LOS InSAR measurements from many viewing geometries. We find that projecting LOS measurements to the vertical direction using the incidence angle of the satellite sensor (and implicitly assuming no horizontal motions are present) may result in large errors depending on the magnitude of horizontal motion and on the steepness of the incidence angle. We quantify these errors as the maximum expected error from simulated LOS observations based on a Mogi deformation model. However, we recommend to use LOS observations from several image geometries wherever data are available, in order to solve for vertical and E–W oriented horizontal motion. For an anthropogenic deformation phenomenon observed in seven independent InSAR analyses of Envisat SAR data from the Sydney region, Australia, we find that the strong horizontal motion present could lead to misinterpretation of the actual motion direction when projecting LOS measurements to vertical (uplift instead of subsidence). In this example, the difference between multi-geometry data fusion and vertical projection of LOS measurements (at an incidence angle of 33.8°) reach up to 67% of the maximum vertical displacement rate. Furthermore, the position of maximum vertical motion is displaced horizontally by several hundred metres when the LOS measurements are projected.

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Section: Multi-geometry Data Fusionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Resolving Three-Dimensional Surface Motion with InSAR: Constraints from Multi-Geometry Data Fusion

2019

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“…This effect will be absorbed to a large extent by the atmospheric phase screen, but some residual effects may remain. In case of wide-area InSAR processing (over several hundreds of km), these effects would need to be evaluated prior to datum connection, and if found to be significant, the deformation estimates corrected for Fuhrmann et al (2015).…”

Section: The Ijmuiden Experimentsmentioning

confidence: 99%

InSAR datum connection using GNSS-augmented radar transponders

Mahapatra

Marel

Leijen

et al. 2017

J Geod

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“…First, we calculated the mean LOS displacement rate from InSAR within a circular area around each GPS station and then calculated its difference with the GPS displacement rate (called the observed difference). We then set up the cost function related to the observed differences and modeled the differences [26,27]:…”

Section: Methodsmentioning

confidence: 99%

Surface Deformation from Sentinel-1A InSAR: Relation to Seasonal Groundwater Extraction and Rainfall in Central Taiwan

et al. 2019

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Extracting groundwater for agricultural, aquacultural, and industrial use in central Taiwan has caused large-scale land subsidence that poses a threat to the operation of the Taiwan High Speed Railway near Yunlin County. We detected Yunlin subsidence using the Sentinel-1A Synthetic Aperture Radar (SAR) by the Small BAseline Subset (SBAS) method from April 2016 to April 2017. We calibrated the initial InSAR-derived displacement rates using GPS measurements and reduced the velocity difference between the two sensors from 15.0 to 8.5 mm/a. In Yunlin’s severe subsidence regions, cumulative displacements from InSAR and GPS showed that the dry-season subsidence contributed 60%–74% of the annual subsidence. The InSAR-derived vertical velocities matched the velocities from leveling to better than 10 mm/a. In regions with few leveling measurements, InSAR increased the spatial resolution of the vertical velocity field and identified two previously unknown subsidence spots over an industrial zone and steel factory. Annual significant subsidence areas (subsidence rate > 30 mm/a) from leveling from 2011 to 2017 increased with the declining dry-season rainfalls, suggesting that the dry-season rainfall was the deciding factor for land subsidence. A severe drought in 2015 (an El Niño year) dramatically increased the significant subsidence area to 659 km2. Both InSAR and leveling detected similarly significant subsidence areas in 2017, showing that InSAR was an effective technique for assessing whether a subsidence mitigation measure worked. The newly opened Hushan Reservoir can supply surface water during dry seasons and droughts to counter rain shortage and can thereby potentially reduce land subsidence caused by groundwater extraction.

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Estimation of small surface displacements in the Upper Rhine Graben area from a combined analysis of PS-InSAR, levelling and GNSS data

Cited by 38 publications

References 40 publications

Resolving Three-Dimensional Surface Motion with InSAR: Constraints from Multi-Geometry Data Fusion

Resolving Three-Dimensional Surface Motion with InSAR: Constraints from Multi-Geometry Data Fusion

InSAR datum connection using GNSS-augmented radar transponders

Surface Deformation from Sentinel-1A InSAR: Relation to Seasonal Groundwater Extraction and Rainfall in Central Taiwan

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