Reconstruction of stress trajectory field in Nankai subduction zone based on drilling data

This paper presents some results of stress field reconstruction in the Nankai Trough subduction zone located within the area bounded by 136.3°–137°E and 33°–33.5°N where 12 scientific wells were drilled during Nankai Trough Seismogenic Zone Experiment expeditions of the Integrated Ocean Drilling Program and International Ocean Discovery Program. We use the logging data to derive orientations of the maximum principal stress axis at different depths followed by the reconstruction of stress orientations in each individual well. From these data, we further derive average stress orientations along the wells and use these data to reconstruct the stress trajectory field taking into account the presence of Megasplay fault. The results are shown as the stress trajectories of the maximum principal horizontal stresses. They are generally consistent with data the World Stress Map Project data.