Subduction megathrusts exhibit a range of slip behaviors spanning from large earthquakes to aseismic creep, yet what controls spatial variations in the dominant slip mechanism remains unresolved. We present multichannel seismic images that reveal a correlation between the lithologic homogeneity of the megathrust and its slip behavior at a subduction zone that is world renowned for its lateral slip behavior transition, the Hikurangi margin. Where the megathrust exhibits shallow slow-slip in the central Hikurangi margin, the protolith of the megathrust changes ~10 km downdip of the deformation front, transitioning from pelagic carbonates to compositionally heterogeneous volcaniclastics. At the locked southern Hikurangi segment, the megathrust forms consistently within pelagic carbonates above thickened nonvolcanic siliciclastic sediments (unit MES), which subduct beyond 75 km horizontally. The presence of the MES layer plays a key role in smoothing over rough volcanic topography and establishing a uniform spatial distribution of lithologies and frictional properties that may enable large earthquake ruptures.

中文翻译：

---

Hikurangi 大逆冲断层滑移行为受沉积物俯冲横向变化的影响

俯冲大逆冲层表现出从大地震到抗震蠕变的一系列滑动行为，但控制主要滑动机制空间变化的因素仍未得到解决。我们展示的多道地震图像揭示了巨型逆冲断层的岩性均匀性与其在以横向滑动行为转变而闻名的俯冲带 Hikurangi 边缘的滑动行为之间的相关性。在大逆冲断层在 Hikurangi 中部边缘表现出浅层缓慢滑动的情况下，大逆冲断层的原岩在变形前沿下倾约 10 公里处发生变化，从远洋碳酸盐岩转变为成分不均一的火山碎屑岩。在锁定的 Hikurangi 南部段，在加厚的非火山硅质碎屑沉积物（MES 单位）上方的远洋碳酸盐中始终形成大型逆冲断层，水平俯冲超过 75 公里。MES 层的存在在平滑粗糙的火山地形和建立可能导致大地震破裂的岩性和摩擦特性的均匀空间分布方面起着关键作用。