Structural approach combining ALOS PALSAR linear feature extraction with field structural and geophysical investigations

Transcription

1 Structural approach combining ALOS PALSAR linear feature extraction with field structural and geophysical investigations 1 Veronika Kopačková, 1 Jan Franěk, 1 Kryštof Verner, 1 Karel Martínek, 2 Michal Tesař 1 Czech Geological Survey, Klárov 3, Prague 1 2 G-IMPULS Praha spol. s r.o., Přístavní 24, Prague 7

2 Overview Hypothesis Site description Methods Results, validation Conclusions

3 Hypothesis The authors assume that real fractural systems, discontinuity and fault planes appear in a digital image as spatially structured and oriented systems of small linear features (micro-lineaments) Fracture pattern (including faults and joints) Map of joints exposed on a sandstone bedding plane Fault pattern

4 Boletice test site description Mainly magmatic and metamorphic rocks 5 geological domains were defined as they show different tectonometamorphic evolution (different structural pattern) and different physical property. For each geological domain the statistics was employed individually.

5 Methods Computer based technique to automatically extract linear features from ALOS PALSAR image and to further assess their spatial pattern Visual interpretation of DEM Validation: Structural field investigations Field geophysics: Symmetric Resistivity Profiling (SRP), Seismic refraction (SR)

6 ALOS PALSAR Sensor Aquisiton Band Spatial resolution ALOS PALSAR L, HH polarisation 12.5 m Active microwave sensor using L band frequencies to archive data Joint project of JAXA and JAROS Cloud-free, night/day images

7 ALOS PALSAR processing ALOS PALSAR Orthorectification Double transformation Lineament detection -Azimuth dependent gradient images -2nd order derivation Kernel filter Lineament extraction Correction of line geometry Geostatistical analysis -line topology, orientation (azimuth), length -Lineament Density Structural interpretation Validation

8 Validation: field surveys (spring 2010) Symmetric Resistivity Profiling (SRP) &Seismic refraction (SR) Field structural investigations SRP

9 Results: Tectonic interpretation using ALOS PALSAR derivatives

10 Results: Visual interpretation of DEM

11 Lineament density and the geophysics results Faults: geological archive map RADAR: New lineaments Low Lineament Kernel Density High

12 Validation: Lineament density and Symmetric Resistivity Profiling Resisitvity (, Ωm) Profile (m) Linear model: Model R R Square Sig. Linear,62,41,000 Lineament Ddensity Profile (m)

13 Validation: Visual interpretation of DEM and the geophysiscs results Fault, geological archive map DEM: New lineaments

14 Rose diagrams: radar/dmr lineaments sorted by their orientation and length Validation: Field structural investigations Dominant: N-S/NNE-SSW, ENE-WSW Others: ESE-WNW

15 Validation: Field structural investigations Dominant: NS/NNE-SSW Secondary: NW-SE NE-SW EW/ESE-WNW

16 Validation: Field structural investigations Dominant: NE-SW, Secondary: SE-NW, NNE-SSW E-W

17 Validation: Field structural investigations Dominant: SE-NW/EES-WWN Secondary: NNE-SSW

18 Summary ALOS PALSAR micro-lineament spatial pattern derived from the ALOS PALSAR radar image proved to correlate with geophysical and structural data. Structural interpretation on the spatial trend of the micro-lineament density leaded to depiction of the new fault structures they were confirmed by the geophysical profiling. The new method is mainly computer-based and thus objective in contrast to the visual interpretation of shaded reliefs (DEMs). Beneficial method for geological mapping in vegetated regions. Methods for mapping even non-active faults. Further potential for structural, hydrogeological and geophysical applications.

19 Thank you for your attention. The described research was carried out in the framework of a project Geological investigations to determine potential areas to place a deep geological repository, the Boletice military area; The project funded by RAWRA (Radioactive Waste Repository Authority) and lead by AQUATEST a.s.