Blar i forfatter "Smith, Andrew James"

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    • The evolution of methane vents that pierce the hydrate stability zone in the world's oceans 

      Smith, Andrew James; Flemings, Peter B.; Liu, Xiaoli; Darnell, Kristopher (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-07-16)
      We present a one-dimensional model that couples the thermodynamics of hydrate solidification with multiphase flow to illuminate how gas vents pierce the hydrate stability zone in the world's oceans. During the propagation phase, a free-gas/hydrate reaction front propagates toward the seafloor, elevating salinity and temperature to three-phase (gas, liquid, and hydrate) equilibrium. After the reaction ...

    • Offshore permafrost decay and massive seabed methane escape in water depths >20 m at the South Kara Sea shelf 

      Portnov, Alexey; Mienert, Jurgen; Cherkashov, Georgy; Rekant, Pavel; Semenov, Peter; Serov, Pavel; Vanshtein, Boris; Smith, Andrew James (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-07-14)
      Since the Last Glacial Maximum (~19 ka), coastal inundation from sea-level rise has been thawing thick subsea permafrost across the Arctic. Although subsea permafrost has been mapped on several Arctic continental shelves, permafrost distribution in the South Kara Sea and the extent to which it is acting as an impermeable seal to seabed methane escape remains poorly understood. Here we use >1300 km ...

    • Thermogenic methane injection via bubble transport into the upper Arctic Ocean from the hydrate-charged Vestnesa Ridge, Svalbard 

      Smith, Andrew James; Mienert, Jurgen; Bünz, Stefan; Greinert, Jens (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-04-21)
      We use new gas‐hydrate geochemistry analyses, echosounder data, and three‐dimensional P‐Cable seismic data to study a gas‐hydrate and free‐gas system in 1200 m water depth at the Vestnesa Ridge offshore NW Svalbard. Geochemical measurements of gas from hydrates collected at the ridge revealed a thermogenic source. The presence of thermogenic gas and temperatures of ∼3.3°C result in a shallow top of ...