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The impact of megasplay faulting and permeability contrasts on Nankai Trough subduction zone pore pressures
Author(s) -
Screaton Elizabeth J.,
Ge Shemin
Publication year - 2012
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 - 10.1029/2012gl053595
Subject(s) - geology , accretionary wedge , pore water pressure , permeability (electromagnetism) , subduction , petrology , slip (aerodynamics) , trough (economics) , turbidite , seismology , fault (geology) , geotechnical engineering , sediment , geomorphology , tectonics , genetics , physics , macroeconomics , membrane , biology , economics , thermodynamics
Results of a coupled fluid flow and deformation model indicate that megasplay fault slip may impact excess pore pressures within an accretionary prism. In a simulation with homogeneous low permeability representative of clay‐rich sediment, excess pore pressures build where compression occurs in the hanging wall and directly beneath the splay fault. In another simulation with heterogeneous permeability, the impact of high permeability fault zones and turbidite horizons lessens the effect of the megasplay fault slip. Overall, excess pore pressures are lower for the heterogeneous simulation than for the simulation with uniform low permeability. Within the footwall of the megasplay fault zone, simulated pore pressures increase across a transition from more permeable uplifted turbidites to less permeable clay‐rich sediments. Strong permeability contrasts might provide an alternate explanation for a previously observed decrease in seismic velocity beneath the megasplay fault of the Nankai Trough subduction zone.