„The Analysis of Vertical Displacements on Post-mining Areas with a Complicated Tectonic
Structure using DInSAR and PSInSAR Methods”
Michał Kniotek
Andrzej Leśniak
[email protected]
home.agh.edu.pl/kniotek
[email protected]
home.agh.edu.pl/lesniak
AGH University of Science and Technology
Faculty of Geology, Geophysics and Environmental Protection
Department of Geoinformatics and Applied Computer Science
al. Mickiewicza 30, 30-059 Kraków, Poland
www.agh.edu.pl www.geoinf.agh.edu.pl
Abstract
The main goal of this work is an analysis of vertical displacements (subsidence and uplift) on highly urbanized industrial areas using two satellite radar interferometry methods: Differential Interferometry Synthetic
Aperture Radar (DInSAR) and Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR). To detect ground deformations using the DInSAR method a pair of satellite images is needed, while using PSInSAR
method many satellite images (even tens) are needed. In this work a scope of applicability of both methods is described and detected vertical displacements are compared, which do not overlap with each other. Only the
combination of results allows to present a complex map of vertical displacements in the study area. Satellite images in this work cover the Upper Silesian Coal Basin (USCB) area located in southern Poland. Images are
provided inter alia by European Space Agency and were recorded between 1990 and 2001. Study area is highly urbanized, because of the presence of many active stone coal mines. Vertical displacements presented in
work are conducted by underground mining exploitation and neotectonic movements. In the main, the DInSAR method allows to detect big (a few or several centimeters) and intensive (formed in a few days, 35-140
days) vertical displacements conducted by an underground mining exploitation. In the areas of the detected vertical displacements by using the DInSAR method the coherence is high, due to fact that those areas are highly urbanized (many permanent scatters occur). The PSInSAR method in the main allows to detect small and permanent vertical displacements, which are correlated with neotectonic movements. It is noteworthy that
results obtained using the PSInSAR method have low coherence in the areas of vertical displacements detected by using the DInSAR method. Big and intensive vertical displacements are not detected while using the
PSInSAR method. Only using both methods (DInSAR and PSInSAR) allows to generate a complex map of vertical displacements, which is essential for the realization of local zoning plans in the USCB area.
Upper Silesian Coal Basin (USCB)
The Upper Silesian Coal Basin (USCB) is located in south-western
Poland (Fig. 1). At least 42 underground coal mines are located in this
area (Fig. 2). Fig. 3 shows the mines with their deposits borders1. The
USCB is a highly urbanized industrial area due to active mining extraction. The population in this region is estimated at more than
1,300,000. The USCB has complicated tectonic structure (Fig. 4).2 In
the USCB are observed vertical displacements conducted by an underground mining exploitation and neotectonic movements.
Fig. 2 — Mines in Upper Silesian Coal Basin (USCB)
Fig. 1 — Upper Silesian Coal Basin (USCB)
Synthetic Aperture Radar (SAR)
Synthetic Aperture Radar (SAR) is a microwave imaging system. It has cloud-penetrating capabilities because it uses microwaves.
Measurements of travel path variations as a function of the satellite position and time of acquisition allow measurement of centimetric surface deformations of the terrain. Satellite images are recorded even at night. A satellite SAR can observe the same large area
from slightly different look angles. This can be done either simultaneously (with two radars mounted on the same platform) or at different times by exploiting repeated orbits of the same satellite.3
Fig. 3 — Mines with deposits borders in Upper Silesian Coal Basin (USCB)
Fig. 4 — Mines and tectonics in USCB
Fig. 5 — Mines, DInSAR vertical displacements areas [km2], PSInSAR vertical displacements [mm] in USCB
Differential Interferometry Synthetic Aperture Radar (DInSAR)3,4
The DInSAR method is used to obtain maps of vertical displacements (uplifts and subsidences) that occurred during the time period between recording the satellite images. To use this method a pair of satellite images and an
external Digital Elevation Model (DEM) is needed. Alternatively, a third satellite image can be used instead of the
DEM. Satellite images must contain data from the same area at different but close times. DEM is used to remove
the topographic part from an interferogram. The DInSAR method allows for detection of large (several centimeters)
and intensive (formed in a few days, 35-140 days) vertical displacements. Satellite images in this work were provided by European Space Agency and were recorded between 1996 and 2001 by ERS-2 satellite. Authors processed
27 pairs of satellite images with maximum 200m baseline and maximum 140-day time difference. Fig. 5 presents all
areas (in square kilometers) of vertical displacements detected by using DInSAR method. Fig, 6-8 show vertical displacements from interferograms after phase unwrapping. Particularly interesting are the vertical displacements
presented in Fig. 8 from 1999, which reached 70 mm in 35 days.
Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR)
Fig. 6 — DInSAR vertical displacements from 19 June 1996 to 02 October 1996 (105 days) [mm], mines, PSInSAR
vertical displacements [mm] in Upper Silesian Coal Basin
3
The PSInSAR method allows for detection of small and permanent vertical displacements. To detect ground deformations using PSInSAR method many satellite images (over ten) are needed. Satellite images used in this work
were obtained between 1990-2001.5 Fig. 5-8 presents vertical displacements detected by using the PSInSAR method. The vertical displacements of maximum amplitude equal to 5.4 mm have been detected over 11 years. The
largest subsidences (up to 5.4 mm) are observed near areas of subsidences detected using the DInSAR method.
Most of the vertical displacement points in the USCB are classified as subsidences, with only some points classified
as uplifts. It is noteworthy that permanent scatter points do not occur in green zones (woods and fields).
Conclusions
Fig. 7 — DInSAR vertical displacements from 22 October 1997 to 31 December 1997 (70 days) [mm], mines,
PSInSAR vertical displacements [mm] in Upper Silesian Coal Basin
In this work the applicability of PSInSAR and DInSAR methods was described. The detected vertical displacements were compared. Authors concluded that they do not overlap with each other. Vertical displacements presented in work are results of underground mining exploitation and neotectonic movements. The vertical displacements detected using the DInSAR method are located in densely populated and highly industrialized regions. Generally, the PSInSAR method allows for detecting small and permanent vertical displacements which are correlated
with neotectonic displacements. Large amplitude and intensive vertical displacements detected with the DInSAR
method are not observed while using the PSInSAR method. Only using both the DInSAR and the PSInSAR methods
allows for generating a complex map of vertical displacements, which is essential for realization of local zoning
plans in the USCB area.
Bibliography
1. MIDAS database [@] http://geoportal.pgi.gov.pl/portal/page/portal/MIDASGIS/start
2. Jureczka J., Kotas A., 1995: Upper Silesian Coal Basin. W: "The Carboniferous system in Poland". Pr. Pol. Inst. Geol., 148, 164-173.
3. Ferretti A., Monti-Guarnieri A., Prati C., Rocca F., „InSAR Principles: Guidelines for SAR Interferometry Processing
and Interpretation”, ESA Publications ESTEC, Noordwijk, The Netherlands, 2007 [@] http://www.esa.int/About_Us/
ESA_Publications/InSAR_Principles_Guidelines_for_SAR_Interferometry_Processing_and_Interpretation_br_ESA_TM-19
4. Rocca F., DINSAR: Differential SAR Interferometry [@] http://earth.esa.int/landtraining07/D1LB5-1-Rocca.pdf
5. Leśniak A., Porzycka S.: Environment monitoring using satellite radar interferometry technique (PSInSAR). Polish
Journal of Environmental Studies, vol. 17 no. 3A, 382--387b (2008).
Fig. 8 — DInSAR vertical displacements from 09 June 1999 to 14 July 1999 (35 days) [mm], mines,
PSInSAR vertical displacements [mm] in Upper Silesian Coal Basin
FRINGE 2015 WORKSHOP, Advances in the Science and Applications of SAR Interferometry and Sentinel-1, InSAR Workshop, 23-27 March 2015, ESA-ESRIN, Frascati (Rome) Italy
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