Shallow Crustal Structure of the Bransfield Basin Using an Autonomous Underwater Hydrophone

  • Published : 20060000

Abstract

We investigated subsurface structures of the Bransfield Basin, the Antarctic with AUH (Autonomous Underwater Hydrophne) which was designed to record abyssal T-waves generated from submarine earthquakes. The data obtained from a multi-channel seismic survey and an AUH were used for this study. A seismic reflection method was applied to the multi-channel seismic survey data in order to identify bathymetry and sedimentary structures, and the signals recorded in the AUH were used to obtain deep structures as we applied a seismic refraction method. Even though we couldn’t investigate deeper and detailed structure in study area because of lack of Airgun’s capacity, the AUH showed possibilities for being used for a marine seismic survey. From this experiment, we decided the upper and lower sediment layer velocities, detected irregular basement topography probably caused by submarine volcanic/magmatic activities, and retrieved the velocity of the basement and the depth of the sediment layer/basement boundary.

Keywords

References

  1. Barker, D. H. N., and J. A. Austin Jr. (1998), Rift propagation, detachment faulting, and associated magmatism in Bransfield Strait, Antarctic, J. Geophys. Res., 103(B10), 24, 017-24, 043
  2. Barker, D. H. N., G. K. Christeson, J. A. J. Austin, and I. W. D. Dalziel (2003), Backarc basin evolution and cordilleran orogenesis: Insights from new ocean-bottom seismograph refraction profiling in Bransfield Strait, Antarctica, Geology, 31, 107-110 https://doi.org/10.1130/0091-7613(2003)031<0107:BBEACO>2.0.CO;2
  3. Christeson, G. L., D. H. N. Barker, J. A. Austin Jr., and I. W. D. Dalziel (2003), Deep crustal structure of Bransfield Strait: Initiation of a back arc basin by rift reactivation and propagation, J. Geophys. Res., 108(B10), 2492 https://doi.org/10.1029/2003JB002468
  4. Dietrich, R., et al. (2001). ITRF coordinates and plate velocities from repeated GPS campaigns in Antarctica; an analysis based on different individual solutions, J. Geod., 74, 756-766 https://doi.org/10.1007/s001900000147
  5. Dziak, R. P., Bohnenstiehl, D. R., Matsumoto, H., Fox, C. G, Smith, D. K., Tolstoy, M., Lau, T-K, Haxel, J. H. and Fowler, M. J. (2004), P- and T-wave detection thresholds, Pn velocity estimate, and detection of lower mantle and core P-waves on ocean sound-channel hydrophones at the Mid-Atlantic Ridge, Bulletin of the Seismological society of America, 94(2), 665-677 https://doi.org/10.1785/0120030156
  6. Fox, C. G., Dziak, R. P., Matsumoto, H. and Schreiner, A. E. (1994), Potential for monitoring low-level seismicity on the Juan de Fuca Ridge using military hydrophone arrays. Mar. Technol. Soc. J., 27 (4), 22-30
  7. Gonzalez-Casado, J. M., J. L. Giner-Roles, and J. López- Martinez (2000), Bransfield Basin, Antarctic Peninsula: Not a normal backarc basin, Geology, 28, 1043-1046 https://doi.org/10.1130/0091-7613(2000)28<1043:BBAPNA>2.0.CO;2
  8. Gracia, E., M. Canals, M. Li Farran, M. J. Prieto, J. Sorribas, and GEBRA Team (1996), Morphostructure and evolution of the central and eastern Bransfield Basins (NW Atarctic Peninsula), Mar. Geophys. Res., 18, 429-448 https://doi.org/10.1007/BF00286088
  9. Johnson, S. H. (1976), Interpretation of split-spread refraction data in terms of plane dipping layers, Geophysics, 41, 418-424 https://doi.org/10.1190/1.1440623
  10. Larter, R. D., and P. F. Barker (1991), Effects of ridge crest-trench interaction on Antarctic-Phoenix spreading: Forces on a young subducting plate, J. Geophys. Res., 96(B12), 19, 583-19, 607
  11. Lawver, L. A., R. A. Keller, M. R. Fisk, and J. A. Strelin (1995), Bransfield Strait, Antarctic Peninsula: Active extension behind a dead arc, in Back-arc Basins: Tectonics and Magmatism, edited by B. Taylor, pp. 315-342, Plenum, New York
  12. Kearey, P. (1991), An Introduction to Geophysical Exploration, Blackwell Science
  13. Prieto, M. J., M. Canals, G. Ercilla, and M. Batist (1998), Structure and geodynamic evolution of the Central Bransfield Basin (NW Antarctica) from seismic reflection data, Marine Geology, 149, 17-38 https://doi.org/10.1016/S0025-3227(98)00038-3
  14. Robertson Maurice, S. D., D. A. Wiens, P. J. Shore, E. Vera, and L. M. Dorman (2003), Seismicity and tectonics of the South Shetland Islands and Bransfield Strait from a regional broadband seismograph deployment, J. Geophys. Res., 108(B10), 2461, doi:10.1029/2003JB002416
  15. Tolstoy, I. and M. Ewing (1950), The T phase of shallow-focus earthquakes, Bulletin of the Seismological Society of America, 40, 25-51
  16. Yilmaz, O., 1987. Seismic Data Processing. Society of Exploration Geophysicists, Tulsa