Radar Remote Sensing: Monitoring Ground Deformations and Geohazards from Space

Transcription

1 Radar Remote Sensing: Monitoring Ground Deformations and Geohazards from Space Xiaoli Ding Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic University

2 A Question 100 km 100 km

3 InSAR Interferometric Synthetic Aperture Radar A radar remote sensing technology, capable of measuring large-area deformations with high resolution and accuracy

4 Working Process of InSAR Ground station SAR images Deformation measurements Users

5 GPS Satellite Radar Antennas (Phased Array Antennas) SAR Satellites

6 SAR Imaging Active remote sensing Some ability of penetration Two components of results: amplitude and phase 6

7 Amplitude component Phase component

8 φ π 0 π

9 Applications of SAR Images Change detection Environmental and agricultural applications Military applications Interferometric applications 9

10 Interferometry and InSAR Concept of Interferometry: R 1 Constructive (in phase) Destructive (out of phase) R 2 Interference fringes Double-slit experiment (Thomas Young, 1801) 10

11 Concept of InSAR: R 1 R 2 Interference fringes

12 π 0 π SAR Interferometry Amplitude Master Slave Phase

13 SAR Interferometry Interferogram - = π 0 π

14 SAR Interferogram Contains information on Topography Surface deformation Systematic errors Noises The method has been explored for many applications since about 20 years ago 14

15 1st Spaceborne InSAR DEM Result Topographic map of Cottonball Basin in Death Valley (Zebker et al.,1988) 15

16 1st InSAR Deformation Measurement Salton Sea area, south California (Zebker et al, 1989 ) 16

17 1st InSAR Earthquake Study The displacement field of Landers earthquake (Massonnet et al., 1993) 17

18 SRTM Mission Shuttle Radar Topography Mission (SRTM) NASA/JPL s space shuttle InSAR system Launched on Feb. 11, m Radar 1 GPS Receiver C/X band SAR Radar 2 18

19 Flew for 11 days km fly height,57 o imaging angle Cover almost all land area (60 o N to 60 o S) Dual frequency (C and X)

20 Co-seismic ground deformation associated with Sichuan earthquake in 2008

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22 Kilauea volcano, Hawaii (Courtesy NASA/JPL)

23 In the late 1990s, InSAR was used to map the deformation of volcanoes during quiescent periods. InSAR-derived surface deformation patterns shed important insights into the structure, plumbing, and state of restless volcanoes (Lu, 2007)

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25 Ice-Sheet Motion Goldstein et al., 1993, JPL Rutford, Antarctic 25

26 Settlement of HK Airport (mm) Settlement map near 1 year (1999) Lam Chau Chek Lap Kok

27 Accumulative Subsidence in Shanghai

28 Ground Subsidence in Xi an in 05-06

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31 Ground Subsidence is a Global Problem In the United States, more than 17,000 square miles in 45 States

32 Land Subsidence in California Joe Poland, USGS scientist shows subsidence from 1925 and miles southwest of Mendota, CA. Sign reads "San Joaquin Valley California, BM S661, Subsidence 9M, " From USGS Professional Paper 1401-A, "Ground water in the Central Valley, California- A summary report" Photo by Dick Ireland, USGS, ok/hydrosphere/subsurface_water_groundwater.html

33 Landslide Monitoring Interferometric SAR images could provide information on detail slope profiles of the large rock slides occurring on steep slopes and along faults. From the interferograms, faults, rock slumps, block slides, slide scars and debris slopes could be identified displacement image of the landslide of La Valette from to

34 Shortcomings of Traditional InSAR Significantly affected by ground conditions Affected by the atmosphere 34

35 InSAR will not work in heavily vegetated areas! X band (λ = 3.1 cm) C band (λ = 5.6 cm) L band (λ = 23.5 cm)

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37 InSAR does not work well for sites disturbed too much

38 InSAR does not work in steep terrains!

39 InSAR does not work if the surface measured is too smooth!

40 InSAR does not work if the area is too small or a surface does not oriented properly!

41 (a) Atmospheric artifacts in deformation measurements!

42 Recent InSAR Research Efforts Enhance the performance of InSAR by overcoming its problems Apply InSAR to study various scientific and engineering problems InSAR research community is increasing rapidly 42

43 (Rott, 2005) Persistent Scatterer InSAR (PSInSAR) Using a times series of SAR images to get solution in time domain First proposed by Ferretti et al. (2001) 43

44 (Courtesy of TRE)

45 (Courtesy of TRE) 45

46 Subsidence in Southern Taiwan from PSInSAR

47 Subsidence in Southern California from Triple-Difference PSInSAR

48 Comparison with GPS Results 48

49 Shanghai Subsidence ( ) from TCP-InSAR TCP Temporary Coherence Points 12 SAR images were used for this study 49 49

50 Bridge Monitoring with TCP- InSAR Only 4 SAR images were used for this study Deformation of up to 1.2cm between January-July 2009 was detected 50 50

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52 Study of Atmospheric Effects on InSAR Unit: mm (a) 19/02/ /02/1996 (b) 25/03/ /03/1996 In each interferogram a square region of 50 km 50 km is chosen for further study 52

53 Tropospheric Delay Modeling 53

54 Ionospheric effects on co-seismic deformation Measurements - Sichuan earthquake in 2008

55 Corner Reflector InSAR

56 InSAR Related Publications In SCI Database < (May) 56

57 InSAR Research Topics ( ) Earthquake Glacier motion Vocalno Urban subsidence DEM generation Land cover classification Forest mapping Landslides Atmospheric correction Wetland 57

58 Summary InSAR is one of the most powerful geodetic technologies Capability of InSAR is increasing rapidly There are still problems with the technology There will be more and wider applications of the technology 58