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Earthquakes as a coupled shear stress‐high pore pressure dynamical system
Author(s) -
Miller Stephen A.,
Nur Amos,
Olgaard David L.
Publication year - 1996
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 - 10.1029/95gl03178
Subject(s) - geology , hydrostatic equilibrium , coalescence (physics) , pore water pressure , slip (aerodynamics) , shear stress , shear (geology) , induced seismicity , effective stress , hydrostatic pressure , fault gouge , rheology , mechanics , geotechnical engineering , materials science , fault (geology) , seismology , petrology , composite material , thermodynamics , physics , quantum mechanics , astrobiology
The migration, coalescence and localization of slip, seismicity, and zones of high pore pressure are modeled using a porosity reduction mechanism to drive pore pressure within a fault zone in excess of hydrostatic. Increased pore pressure in discrete cells creates zones of low effective stress, which induces slip that may propagate to surrounding cells depending on the local state of stress. At slip, stress is transferred using the solution for a rectangular dislocation in an elastic half‐space, and pore pressures are redistributed by conserving fluid mass. Using simple assumptions about fault rheology and permeability, it is shown that the interaction between shear stress and effective stress evolves to a state of earthquake clustering with repeated events, locked zones, and large variations in fault strength. The model evolves from a uniform shear stress state on a strong fault, to a heterogeneous shear stress state on a weak fault.