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Pressure gradient measurements in volcanic diffuse gas emanations
Author(s) -
Natale Giuseppe,
Hernández Pedro,
Mori Toshiya,
Notsu Kenji
Publication year - 2000
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 - 10.1029/2000gl008540
Subject(s) - volcano , volcanic gases , geology , mineralogy , pressure gradient , atmospheric pressure , geophysics , seismology , oceanography
We describe a differential pressure measurement device which allows one to estimate fluid pressure gradients ranging from 6.3 × 10 −6 to 3.15 × 10 −3 atm/m in soil diffuse volcanic gas emanations. The lower limit roughly corresponds to the atmospheric (static) pressure gradient due to gravity, and should represent the minimum required value for volcanic gases to reach the Earth's surface by viscous flow. In the study of diffuse gas emanations, such as for the purpose of volcanic surveillance, such physical data supplements the geochemical monitoring of concentrations and fluxes of specific substances constituting the flowing gaseous mixture and may be used to infer volcanic mechanical states. We describe laboratory experiments with the device and report on a successful preliminary test with diffuse gas emanations on the Miharayama cone of the Izu‐Oshima volcano (Japan), where the highest fluid pressure gradients have been found to be associated with the highest CO 2 fluxes and lowest CO 2 concentration gradients.