We propose a session exploring advances in understanding megathrust earthquake processes through scientific ocean drilling and onshore analogs, integrating results from IODP and IODP³ Expeditions in the Tohoku area and comparable research at subduction zones globally.The session will emphasize the value of linking fault and rock properties, fluid flow, and earthquake recurrence across space and time, from the megathrust to the outer rise. We welcome contributions that constrain processes from incoming-plate modification, including petit-spot magmatism influencing rupture nucleation and slip propagation, sedimentary records of past tsunamigenic events, and slip-to-trench behavior. We also encourage studies that connect near-surface features and stratigraphy to long-term earthquake and tsunami histories. We invite contributions spanning global subduction systems that combine drilling results with geologic field observations, geophysics, geochemistry, experiments, and modeling to advance understanding of earthquake propagation and tsunami hazard across spatial and temporal scales.

• EP - Earth and Planetary Surface Processes
• MR - Mineral and Rock Physics
• NS - Near Surface Geophysics
• S - Seismology