SAHKE geophysical transect reveals crustal and subduction zone structure at the southern Hikurangi margin, New Zealand

摘要: [1] The Seismic Array Hikurangi Experiment (SAHKE) investigated the structure of forearc and subduction plate boundary beneath southern North Island along a 350 km transect. Tomographic inversion first-arrival travel times was used to derive well-resolved 15–20 deep P wave image crust. The refracted phases migrated reflection events subducting slab geometry crustal structure. In west, Australian Plate Moho depth decreases westward across Taranaki Fault system from 35 ∼28–30 km. east, subducted Pacific oceanic crust is recognized have positive velocity gradient, but becomes less distinct Tararua Ranges, where interface increases in dip at about 15 15°. This bend associated with vertical clusters seismicity, splay fault branching, low-velocity high-attenuation material that we interpret be an underplated sedimentary channel. We infer step down decollement transfers slip on top channel drives local uplift Ranges. Reflections Wairarapa show it listric soles into sediments, which turn abut overriding ∼32 depth, near downdip end strongly locked zone. change spatially correlated transition geodetically determined unlocked areas interface.