Analysis of normal fault populations in the Kumano Forearc Basin, Nankai Trough, Japan: 1. Multiple orientations and generations of faults from 3‐D coherency mapping

摘要: [1] Analyses of normal faults in the Kumano forearc basin Nankai Trough reveal multiple fault populations a region generally thought to be under compression. Most have offsets less than 20 m and dips 60–70° show no growth structures, indicating that were active for short periods time. The oldest generation is older ~0.9 Ma strikes ~50–60°. next strike ~160–170°, are 0.44 Ma, related local uplift along western edge region. youngest cut seafloor; shallow near SE margin curve from ~100° middle survey area ~145° at corner area. pattern two consistent with regional stress (maximum horizontal subparallel trench). Orientations caused by underlying accretionary prism, implying not as stable previously thought. Reconstruction displacements on shows overall extension 2%, concentrated seaward basin. distributed throughout support idea parallel plate convergence direction does reach critical activate or form thrust produce shortening within portion inner wedge.