Skip to main content
Earth, Planets and Space
Fig. 2 | Earth, Planets and Space

Fig. 2

From: In situ stress magnitude and rock strength in the Nankai accretionary complex: a novel approach using paired constraints from downhole data in two wells

Fig. 2

a Schematic of local stress state at the circumference of a vertical borehole relative to the far-field maximum and minimum horizontal stresses (S Hmax and S hmin). Compressional breakouts (BO) form where differential stresses at the borehole wall exceed the rock strength. Azimuth (θ) is measured from S Hmax. At the edge of a breakout, stress and strength are in equilibrium, such that breakout width can be used to determine the far-field stress magnitudes (e.g., Zhou 1994). b Unwrapped borehole resistivity (Ω m) images from 0° to 360° azimuth, for Holes C0002A (left) and C0002F (right), over the interval from 1350 to 1400 mbsf, documenting well-developed compressional borehole breakouts at Hole C0002A (drilled in riserless mode) and no borehole breakouts at Hole C0002F (drilled in riser mode with weighted mud)

Back to article page