Slow slip events (SSEs) accommodate a significant proportion of tectonic plate motion at subduction zones, yet little is known about the faults that actually host them. The shallow depth (<2 km) of well-documented SSEs at the Hikurangi subduction zone offshore New Zealand offers a unique opportunity to link geophysical imaging of the subduction zone with direct access to incoming material that represents the megathrust fault rocks hosting slow slip. Two recent International Ocean Discovery Program Expeditions sampled this incoming material before it is entrained immediately down-dip along the shallow plate interface. Drilling results, tied to regional seismic reflection images, reveal heterogeneous lithologies with highly variable physical properties entering the SSE source region. These observations suggest that SSEs and associated slow earthquake phenomena are promoted by lithological, mechanical, and frictional heterogeneity within the fault zone, enhanced by geometric complexity associated with subduction of rough crust.

慢滑事件（SSEs）在俯冲带的构造板块运动中占很大比例，但对于真正引起它们的断层知之甚少。新西兰近海Hikurangi俯冲带上有据可查的SSE的浅层深度（<2 km）提供了独特的机会，将俯冲带的地球物理成像与直接进入的进入材料联系起来，这些进入的材料代表了缓滑作用的巨推断层岩石。最近的两次国际海洋发现计划探险队对该进料进行了采样，然后将它们沿薄板界面立即下沉。钻探结果与区域地震反射图像有关，揭示了进入SSE震源区的具有高度可变物理特性的非均质岩性。