Validation of DInSAR displacement measurements in permafrost environments

Naomi Short1, Anne-Marie LeBlanc2, Stephen Wolfe2, Peter Morse2 and Greg Oldenborger2

1Canada Centre for Remote Sensing, 560 Rochester St., Ottawa 2 Geological Survey of , 601 Booth St., Ottawa

Arctic Products Validation and Evolution Workshop, Canada’s Natural Resources – Now and for Ottawa,the Future Nov. 12th, 2014 1

Overview

Principles of Interferometric SAR (InSAR)

Example Products – and Iqaluit

Validation Methods

Summary

Canada’s Natural Resources – Now and for the Future 2 InSAR principles

Path difference results in a phase difference or shift

Phase shift can be converted to ground displacement

Canada’s Natural Resources – Now and for the Future 3

InSAR applied to permafrost terrain

Seasonal Long-term settlement and heave thaw settlement

Canada’s Natural Resources – Now and for the Future 4 InSAR data and processing

• RADARSAT-2 summer data sets (snow-free)

• Spotlight or Ultra-fine resolution (1-4 m)

• High resolution external DEM

• InSAR stacking to extract summer rate of displacement. Seasonal settlement typically < 10 cm / four months

Canada’s Natural Resources – Now and for the Future 5 May 21 July 8 Aug. 01 Aug. 25 Sep.18

RADARSAT-2 acquisitions © MDA, 2010

May 21 – July 8 July 8 – Aug 01 Aug 01 – Aug 25 Aug 25 – Sep 18 DEM

+ Interferograms

InSAR stacking Cumulative displacement May 21 – Sep. 18, 2010

Canada’s Natural Resources – Now and for the Future 6 Example products

Yellowknife

Iqaluit Yellowknife

Photo credit: Anne-Marie LeBlanc Iqaluit

Canada’s Natural Resources – Now and for the Future 7 Yellowknife

Canada’sShort Natural et Resourcesal., 2011. – Now Open and for File the 7030,Future Geological Survey of Canada8 Iqaluit seasonal terrain displacement, preliminary map

Short et al., (2012) Canadian Geoscience Map No. 66. Canada’s Natural Resources – Now and for the Future 9 Validation Methods

1. Field observations 2. Field measurements 3. Surficial geology vectors 4. Electrical resistivity surveys 5. Borehole and historical engineering reports Photo credit: Anne-Marie LeBlanc

Canada’s Natural Resources – Now and for the Future 10 1. Field observations

– In urban locations, one can assume the infrastructure was level was first constructed, sometimes dates of construction are known – Natural areas are more difficult to assess – Limited to point and small area observations

Photo credit: Anne-Marie LeBlanc

Canada’s Natural Resources – Now and for the Future 11 2. Field measurements

– Thaw tubes – Probing for active layer thickness – Point and small area coverage

Photo credit: Anne-Marie LeBlanc

Canada’s Natural Resources – Now and for the Future 12 Iqaluit thaw tubes

Short et al. (2014)

Canada’s Natural Resources – Now and for the Future 13 3. Surficial geology vectors

– Geology and sediment types indicate thaw settlement potential – large area ~1 - 10 km2, potentially larger at lower resolution

Photo credit: Anne-Marie LeBlanc

Canada’s Natural Resources – Now and for the Future 14 Iqaluit surficial geology vectors

Photo credit: Anne-Marie LeBlanc

Allard et al. (2012)

Canada’s Natural Resources – Now and for the Future 15 Iqaluit InSAR with surficial geology vectors

Summer 2011 (June 22- Sept 26)

Ground displacement

Stable ground

RADARSAT-2 Spotlight Surface moved down InSAR stack -0.5 to -2 cm June to September 2011 -2 to -4.5 cm

-4.5 to -8.5 cm No data

RADARSAT-2 Spotlight stack

Canada’s Natural Resources – Now and for the FutureShort et al. (2012) 16 Yellowknife surficial geology

Mapping resolution ~100m.

Canada’s Natural Resources – Now and for the Future 17 Canada’s Natural Resources – Now and for the Future 18 4. Electrical resistivity surveys

– Maps of frozen or unfrozen ground at depth (<6m), based on electrical conductivity of sediments – Lines surveyed using ground conductivity meter (Geonics EM31) points interpolated to create a map. – Medium area ~1 km2

Canada’s Natural Resources –Geophysics Now and for by the Greg Future Oldenborger 19 Validation Methods - medium area ~1 km2

• Electrical resistivity surveys – Maps of frozen or unfrozen ground at depths based on electrical conductivity of sediments

Canada’s Natural Resources – Now and for the Future 20 Iqaluit, InSAR and electrical resistivity survey data

Canada’s Natural Resources – Now and for the Future 21 5. Borehole data and historical engineering reports

• Borehole data – Sediment properties at depth – Ground temperatures – Active layer thickness • Historical engineering reports

Canada’s Natural Resources – Now and for the Future 22 Yellowknife airport

Canada’s Natural Resources – Now and for the Future 23 Seto et al., 2004 Forrest Drive, Yellowknife

“The soils encountered in the test holes in this area exist with numerous ice lenses. On site visual examination of samples recovered from the test holes at the time of drilling indicate percentage of clear segregated ice to be of the order of 10 to 15 percent. On degradation of permafrost, this area will be subjected to subsidence and could result in settlement problems for the structures, utilities and roadway. The settlements are anticipated to be of the order of 1 to 2 feet excluding the deformations within the surface peat.” Ripley, Klohn & Leonoff (1971) Canada’s Natural Resources – Now and for the Future 24 Summary

• A variety of methods and data sources can be used to validate displacement trends in InSAR data

• Validation methods are largely qualitative, and simply confirm that the satellite displacement trend is realistic

• Quantitative methods are possible, but tend to be point only and difficult to extract to large areas

• Validation demonstrates that the InSAR information is reliable enough to be useful for infrastructure planning

• Validation shows that areas with the highest seasonal displacements are often sites of long-term permafrost change.

Canada’s Natural Resources – Now and for the Future 25 Acknowledgements

• Work funded by CSA-GRIP and NRCan Remote Sensing Science and Climate Change Geoscience Programs • Additional fieldwork contributions by Christopher Stevens, Peter Morse and Wendy Sladen.

References

• Short, N., C.W. Stevens and S.A. Wolfe, 2011. Seasonal surface displacement derived from InSAR, Yellowknife and Surrounding Area, . Geological Survey of Canada, Open File 7030, 11 p. • Short, N., A –M. LeBlanc, W. E. Sladen, M. Allard, V. Mathon-Dufour, 2012. Seasonal surface displacement derived from InSAR, Iqaluit, Nunavut. Canadian Geoscience Map No. 66, Geological Survey of Canada, Ottawa, 1 sheet, 1 CD-ROM. • Allard, M., Doyon, J., Mathon-Dufour, V., LeBlanc, A.-M., L’Hérault, E., Mate, D., Oldenborger, G.A. and Sladen W.E. 2012. Surficial geology, Iqaluit, Nunavut. Geological Survey of Canada, Canadian Geoscience Map 64, scale 1:15,000. doi:10.4095/289503. • Short, N., LeBlanc, A.-M., Sladen, W., Oldenborger, G., Mathon-Dufour, V. and Brisco, B. 2014. RADARSAT-2 D- InSAR for ground displacement in permafrost terrain, validation from , Baffin Island, Canada. Remote Sensing of Environment. 141, doi: 10.1016/j.rse.2013.10.016 • Seto, J.T.C., Parry, N.S., Hayley, D.W., and Trudel, L. 2004. Investigation and assessment of runways overlying warm permafrost, Yellowknife airport. In Proceedings, 12th International Specialty Conference on Cold Regions Engineering, 16-19 May 2004, Edmonton, Alberta. Canadian Society of Civil Engineering. • Ripley, Klohn and Leonoff International Ltd. 1971. Proposed Forrest Park Subdivision, Yellowknife, NWT. Report to Reid Crowther and Partners Ltd. Job No. AL1041, 8 p. Canada’s Natural Resources – Now and for the Future 26