Distributed natural gas venting offshore along the Cascadia margin
Riedel, M.; Scherwath, M.; Römer, M.; Veloso, M.; Heesemann, M.; Spence, G.D. (2018). Distributed natural gas venting offshore along the Cascadia margin. Nature Comm. 9(1): 14 pp. https://dx.doi.org/10.1038/s41467-018-05736-x
In: Nature Communications. Nature Publishing Group: London. ISSN 2041-1723; e-ISSN 2041-1723, more
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| Authors | | Top |
- Riedel, M.
- Scherwath, M.
- Römer, M.
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- Veloso, M.
- Heesemann, M.
- Spence, G.D.
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| Abstract |
Widespread gas venting along the Cascadia margin is investigated from acoustic water column data and reveals a nonuniform regional distribution of over 1100 mapped acoustic flares. The highest number of flares occurs on the shelf, and the highest flare density is seen around the nutrition-rich outflow of the Juan de Fuca Strait. We determine ∼430 flow-rates at ∼340 individual flare locations along the margin with instantaneous in situ values ranging from ~6 mL min−1 to ∼18 L min−1. Applying a tidal-modulation model, a depth-dependent methane density, and extrapolating these results across the margin using two normalization techniques yields a combined average in situ flow-rate of ∼88 × 106 kg y−1. The average methane flux-rate for the Cascadia margin is thus estimated to ∼0.9 g y−1m−2. Combined uncertainties result in a range of these values between 4.5 and 1800% of the estimated mean values. |
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