Figure F5. A. Cross-hole response in Hole 1027C CORK to long-term flow into Hole U1301B, 2.4 km away (Fisher et al., 2008). Pressure record from Hole 1027C (blue line), corrected for tidal loading and other instantaneous responses, indicates basement permeability shown, a range lower than that indicated by packer tests or larger scale methods. B. Geometry of cross-hole pressure response. Hole 1027C is oriented along a trend oblique to the structural strike of basement. The direction of greatest permeability is hypothesized to be along structural strike, N20E (blue dashed arrow), whereas cross-hole response direction is N70E (red dashed arrow), an azimuthal angle of 50°. C. Calculated effective permeability as a function of testing angle in an anisotropic medium. The full cross-hole experiment, with monitoring wells at different angles and depths, will test for permeability anisotropy. IODP = Integrated Ocean Drilling Program.
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