Seismic anisotropy at Hydrate Ridge

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Read Full Article (file size: 240965 bytes) Cited by GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L01306, doi:10.1029/2005GL023945, 2006 Seismic anisotropy at Hydrate Ridge Dhananjay Kumar John A. and Katherine G. Jackson, School of Geosciences, University of Texas at Austin, Austin, Texas, USA Mrinal K. Sen John A. and Katherine G. Jackson, School of Geosciences, University of Texas at Austin, Austin, Texas, USA Nathan L. Bangs John A. and Katherine G. Jackson, School of Geosciences, University of Texas at Austin, Austin, Texas, USA Chengshu Wang John A. and Katherine G. Jackson, School of Geosciences, University of Texas at Austin, Austin, Texas, USA Ingo Pecher John A. and Katherine G. Jackson, School of Geosciences, University of Texas at Austin, Austin, Texas, USA Abstract P-wave velocity increases in the presence of gas hydrates and decreases in the presence of free gas in the sediments, making it an excellent means to investigate gas hydrate systems. However, seismic velocity is typically derived from surface seismic data without consideration of seismic anisotropy. The presence of anisotropy in the hydrate bearing sediments adds an additional complexity in data analysis; however anisotropy can help reveal the distribution of hydrates. Here we report on the evidence of seismic anisotropy at Hydrate Ridge along the Cascadia convergent margin. We find that the south summit is anisotropic, while the basin side (east of south summit) is isotropic. Anisotropy is likely caused by the hydrate veins. We interpret the anisotropy parameters in terms of the distribution and fabric of gas hydrates. Received 29 June 2005; accepted 17 November 2005; published 12 January 2006. Index Terms: 7220 Seismology: Oceanic crust; 7260 Seismology: Theory; 7270 Seismology: Tomography (6982, 8180); 7290 Seismology: Computational seismology. Read Full Article (file size: 240965 bytes) Cited by Citation: Kumar, D., M. K. Sen, N. L. Bangs, C. Wang, and I. Pecher (2006), Seismic anisotropy at Hydrate Ridge, Geophys. Res. Lett., 33, L01306, doi:10.1029/2005GL023945. Copyright 2006 by the American Geophysical Union.

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