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Bottom pressure signals at the TAG deep‐sea hydrothermal field: Evidence for short‐period, flow‐induced ground deformation
Author(s) -
Sohn Robert A.,
Thomson Richard E.,
Rabinovich Alexander B.,
Mihaly Steven F.
Publication year - 2009
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 - 10.1029/2009gl040006
Subject(s) - hydrothermal circulation , geology , seafloor spreading , ridge , amplitude , seabed , permeability (electromagnetism) , mineralogy , geophysics , seismology , petrology , oceanography , paleontology , optics , physics , chemistry , biochemistry , membrane
Bottom pressure measurements acquired from the TAG hydrothermal field on the Mid‐Atlantic Ridge (26°N) contain clusters of narrowband spectral peaks centered at periods from 22 to 53.2 minutes. The strongest signal at 53.2 min corresponds to 13 mm of water depth variation. Smaller, but statistically significant, signals were also observed at periods of 22, 26.5, 33.4, and 37.7 min (1–4 mm amplitude). These kinds of signals have not previously been observed in the ocean, and they appear to represent vertical motion of the seafloor in response to hydrothermal flow ‐ similar in many ways to periodic terrestrial geysers. We demonstrate that displacements of 13 mm can be produced by relatively small flow‐induced pressures (several kPa) if the source region is less than ∼100 m below the seafloor. We suggest that the periodic nature of the signals results from a non‐linear relationship between fluid pore pressure and crustal permeability.