"Gas escape features off New Zealand: Evidence of massive release of methane from hydrates" by B. Davy, I. Pecher, R. Wood, L. Carter & K. Gohl, GRL 37 (2010) doi:10.1029/2010GL045184

Geophysical Research Letters, 37 (2010) L21309; doi:10.1029/2010GL045184

Gas escape features off New Zealand: Evidence of massive release of methane from hydrates

Bryan Davy, Ingo Pecher, Ray Wood (Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand), Lionel Carter (Antarctic Research Centre, Victoria University Wellington, Wellington, New Zealand) and Karsten Gohl (Department of Geosciences, Alfred Wegener Institute for Polar Sciences, Bremerhaven, Germany)

Abstract

Multibeam swath bathymetry data from the southwest margin of the Chatham Rise, New Zealand, show gas release features over a region of at least 20,000 km². Gas escape features, interpreted to be caused by gas hydrate dissociation, include an estimated a) 10 features, 8–11 km in diameter and b) 1,000 features, 1–5 km in diameter, both at 800–1,100 m water depth. An estimated 10,000 features, ∼150 m in diameter, are observed at 500–700 m water depth. In the latter depth range sub-bottom profiles show similar gas escape features (pockmarks) at disconformities interpreted to mark past sea-level low stands. The amount of methane potentially released from hydrates at each of the largest features is ∼7*10¹² g. If the methane from a single event at one 8–11 km scale pockmark reached the atmosphere, it would be equivalent to ∼3% of the current annual global methane released from natural sources into the atmosphere.

Received 19 August 2010; accepted 27 September 2010; published 10 November 2010.

Citation: Davy, B., I. Pecher, R. Wood, L. Carter, and K. Gohl (2010), Gas escape features off New Zealand: Evidence of massive release of methane from hydrates, Geophys. Res. Lett., 37, L21309, doi:10.1029/2010GL045184.

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