High-Resolution P-wave Seismic Reflection Imaging of the Kuwana Active Thrust : 2000 Inabe River Profile

We present new, high-resolution seismic reflection data (2000 Inabe River profile) acquired across the forelimb and backlimb of Kuwana anticline to further image its subsurface geometry. A seismic source (mini-vibrator) and 150-channel digital telemetry recording system were used in an off-end configuration with the nearest receiver adjacent to the source to record seismic waves from deeper reflection points. A 15-m source and geophone spacing give a 7.5-m CMP (common midpoint) spacing on the final section. The nominal CMP stacking fold had 75 traces. We also suppressed coherent noise by repeating source points 5-10 times. After data processing including surface-consistent statics, velocity analysis, normal moveout (NMO) correction, residual statics, CMP stack, and migration, the section was finally depth-converted using stacking velocities. Reflectors imaged on the seismic profile illuminate that fluvial terraces folded across the forelimb and backlimb are consistent with the subsurface structure of the fold imaged in a seismic section, providing insights into the kinematic solution of the underlying active wedge thrust