Figure F5. Seismic and interpretive sections illustrating stratigraphy and structure of the prism toe of the Muroto Transect area (after Heffernan, et al., 2004). This seismic line is through the middle of the 3-D seismic volume and is approximately along the line shown on Figure F1. Sections are perpendicular to the trench axis and parallel to the direction of convergence. Fault 1 is the prominent protothrust. Fault 2 is the frontal thrust. Faults 3 and 4 are older in-sequence imbricate thrusts. Numerous small-offset normal faults are visible in the upper and middle part of the incoming Shikoku Basin sequence. The convergence-related "deformation front" is defined by initial thickening and deformation of the trench fill. The deformation is commonly not resolvable seismically, but indicated by thickening and uplift. The deformation front is also reflected in a change to a subtle seaward tilt of the trench floor. The décollement zone can be recognized as a bright reflector extending at least to and locally beyond the seaward limit of the deformation front. VE = vertical exaggeration.

Figure F5. Seismic and interpretive sections illustrating stratigraphy and structure of the prism toe of the Muroto Transect area (after Heffernan, et al., 2004). This seismic line is through the middle of the 3-D seismic volume and is approximately along the line shown on Figure F1. Sections are perpendicular to the trench axis and parallel to the direction of convergence. Fault 1 is the prominent protothrust. Fault 2 is the frontal thrust. Faults 3 and 4 are older in-sequence imbricate thrusts. Numerous small-offset normal faults are visible in the upper and middle part of the incoming Shikoku Basin sequence. The convergence-related "deformation front" is defined by initial thickening and deformation of the trench fill. The deformation is commonly not resolvable seismically, but indicated by thickening and uplift. The deformation front is also reflected in a change to a subtle seaward tilt of the trench floor. The décollement zone can be recognized as a bright reflector extending at least to and locally beyond the seaward limit of the deformation front. VE = vertical exaggeration.