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Gas escape features off New Zealand: Evidence of massive release of methane from hydrates
Author(s) -
Davy Bryan,
Pecher Ingo,
Wood Ray,
Carter Lionel,
Gohl Karsten
Publication year - 2010
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2010gl045184
Subject(s) - methane , clathrate hydrate , geology , earth science , methane emissions , environmental science , oceanography , hydrate , greenhouse gas , chemistry , organic chemistry
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 km 2 . 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*10 12 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.