Tomographic seismic studies of the methane hydrate stability zone in the Cascadia Margin
Hobro, J.W.; Minshull, T.A.; Singh, S.C. (1998). Tomographic seismic studies of the methane hydrate stability zone in the Cascadia Margin, in: Henriet, J.-P. et al. Gas hydrates: relevance to world margin stability and climate change. Geological Society Special Publication, 137: pp. 133-140. https://dx.doi.org/10.1144/GSL.SP.1998.137.01.10 In: Henriet, J.-P.; Mienert, J. (1998). Gas hydrates: Relevance to world margin stability and climate change. Geological Society Special Publication, 137. The Geological Society: London. ISBN 1-86239-010-X. 338 pp., more In: Hartley, A.J. et al. (Ed.) Geological Society Special Publication. Geological Society of London: Oxford; London; Edinburgh; Boston, Mass.; Carlton, Vic.. ISSN 0305-8719; e-ISSN 2041-4927, more |
| Keywords | Chemical compounds > Organic compounds > Hydrocarbons > Gas hydrates
Chemical compounds > Organic compounds > Hydrocarbons > Saturated hydrocarbons > Acyclic hydrocarbons > Methane
Plate margins
Seismic activity
Marine/Coastal |
| Authors | | Top | - Hobro, J.W.
- Minshull, T.A.
- Singh, S.C.
| | |
| Abstract | A seismic study in the Cascadia Margin in June 1993 focused upon the bottom simulating reflector (BSR) around Hole 889B of the Ocean Drilling Program. Extensive wide-angle and normal-incidence data were collected during two deployments of five ocean bottom hydrophones (OBHs). We have applied a new two-dimensional travel-time inversion method to data from one line within the survey. Data from four OBHs and normal-incidence arrivals are inverted simultaneously, and a distribution of P-wave velocities above the BSR is obtained. These velocities are found to be slightly higher than those given by vertical seismic profile (VSP) and sonic log data from Hole 889B, with velocities of 1.83–1.95 km s−1 occurring immediately above the BSR. Estimates of hydrate concentration derived using two different methods range from 2 to 24% of the pore space. The velocity model provides some support for the existence of a correlation between BSR strength and hydrate concentration above the BSR in this region. |
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