Topographic migration of georadar data: Implications for acquisition and processing

Geophysics - Tập 65 Số 3 - Trang 836-848 - 2000
Frank Lehmann1, Alan G. Green1
1Swiss Fed. Inst. of Tech., Institute of Geophysics, ETH-Honggerberg, CH-8093 Zürich, Switzerland

Tóm tắt

Application of conventional elevation static corrections and migration to wavefield data recorded on irregular surfaces may result in poor reconstructions of complex subsurface features. Particulary poor images may be obtained at locations where the depths to target structures are comparable to undulations in the surface topography. For example, topographic relief of only 1-2 m may be important for the processing of georadar data. We describe an algorithm that allows georadar data to be migrated directly from gently to highly irregular acquisition surfaces. When applied to a variety of complicated synthetic data sets, topographically migrated images are observed to be markedly superior to those produced by two standard processing schemes. Extensive tests demonstrate that topographic migration should be considered in regions characterized by surface gradients ≫10% (i.e., dips ≫6°). For effective topographic migration, lateral and vertical coordinates of the georadar antennas should be determined to better than 10% of the dominant georadar wavelength, and velocities should be known to within 10–20% (e.g., 0.01–0.02 m/ns) of their true values. When applied to data collected across a moderately dipping (∼14°) rock glacier in the Swiss Alps, georadar sections resulting from two standard processing schemes have reflectors with depths and dips that differ by a significant 10–15% from those in the topographically migrated images.

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Tài liệu tham khảo

Annan, A. P., 1992, Ground penetrating radar workshop notes: Sensors&Software Inc.

10.1190/1.1443211

Beres, M., Green, A. G., and Pugin, A., 2000, Georadar mapping of deformed fluvial‐deltaic sediments: The enigmatic Chessel‐Noville Hills of the Rhone Valley: Environ. Engin. Geosci., in press.

Beres, M., Huggenberger, P., Green, A. G., and Horstmeyer, H., 1999, Using two- and three‐dimensional georadar methods to characterize glaciofluvial architecture: Sedim. Geol.129, 1–24.

10.1190/1.1441620

10.1190/1.1441620

10.1190/1.1444258

Claerbout, J. F., 1985, Imaging the Earth’s interior: Blackwell Scientific Publications.

Dallimore, S. R., and Davis, J. L., 1992, Ground penetrating radar investigation of massive ground ice,inPilon, J. A., Ed., Ground penetrating radar: Geol. Surv. Can. Paper 90-4, 41–48.

Dobrin, M. B., and Savit, C. H., 1988, Introduction to geophysical prospecting: McGraw‐Hill Book Co.

10.1190/1.1443271

Grasmück, M., and Green, A. G., 1996, 3D georadar mapping: Looking into the subsurface: Environ. Engin. Geosci.II, 1–6.

10.1190/1.1444026

10.1190/1.1444126

Gray, S. H., and Marfurt, K. J., 1995, Migration from topography: Improving the near‐surface image: Can. J. Expl. Geophys.31, 18–24.

Hu, L. Z., 1992, Imaging pipelines in 3D by ground‐penetrating radar: 62nd Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 352–355.

Leckebusch, J., and Green, A. G., 2000, Georadar,inEllis, L., Ed., Archaeological method and theory: An encyclopedia: Garland, in press.

10.1190/1.1444581

Lines, L., Wu, W.J., Lu, H.X., Burton, A., and Zhu, J., 1996, Migration from topography: experience with an Alberta Foothills data set: Can. J. Expl. Geophys.32, 24–30.

10.1190/1.1442887

Morse, P. M., and Feshbach, H., 1953, Methods of theoretical physics, part I and II: McGraw‐Hill Book Co.

10.1190/1.1442947

10.1190/1.1440828

10.1190/1.1443795

Sheriff, R. E., and Geldart, L. P., 1995, Exploration seismology: Cambridge Univ. Press.

10.1190/1.1442409

Wagner, S., 1992, Creep of alpine permafrost—Investigation on the Murtèl rock glacier: Permafrost and Periglacial Processes,3, 169–173.

10.1190/1.1441752

10.1190/1.1444338

Yilmaz, O., 1987, Seismic data processing: Soc. Expl. Geophys.

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Geophysics

Tập 65 Số 3

836-848

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