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Fault strength drop due to phase transitions in the pore fluid
Author(s) -
Mizoguchi Kazuo,
Takahashi Miki,
Masuda Koji,
Fukuyama Eiichi
Publication year - 2007
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 - 10.1029/2007gl029345
Subject(s) - hydrothermal circulation , quartz , drop (telecommunication) , phase transition , pore water pressure , materials science , fault gouge , phase (matter) , fault (geology) , geology , pressure drop , surface tension , mechanics , composite material , thermodynamics , geotechnical engineering , chemistry , seismology , telecommunications , physics , organic chemistry , computer science
We conducted tri‐axial friction experiments for quartz gouge at hydrothermal conditions to examine the effect of phase transition of water. We observed a decrease of ∼0.05 in its coefficient of friction during the transition between liquid and vapor. This can be interpreted as a local pore pressure increase in the gouge‐filled layer during the phase transition, which is caused by the surface tension of bubbles created between the two different phases. The local pore pressure increase deduces effective normal stress in the gauge layer, which makes a decrease of the frictional strength. The transient friction drop on a fault can play an important role in triggering an earthquake not only in hydrothermal areas but also in typical seismically active areas in the crust where water often contains CO 2 of various concentrations because the CO 2 density in the binary system of H 2 O‐CO 2 controls the pressure‐temperature condition of liquid/vapor phase equilibrium.