Subduction zones are the loci of large subduction earthquakes that might extend to the seafloor, creating devastating tsunamis. Understanding the localization of deformation and the structuration of the shallow subduction is essential to understand the dynamics of tsunamigenic earthquakes.
In the last two decades, plate boundary fault zones of subduction zones have been drilled within the framework of the International Ocean Discovery Program (IODP). At the same time, drilling technology was revolutionized by the introduction of Logging While Drilling tools. These tools provide real-time measurements before a formation gets disturbed by further drilling. Pwavodi and Doan (2024) developed a new methodology to identify the inflow from the formation to the borehole and derive a continuous hydraulic profile along the well.
This methodology has been used in several wells of the Nankai and Tohoku subduction zones. This provides insights into the diversity and time evolution of the hydraulic structures of these subduction zones, in association with megathrust earthquakes and slow slip.