[S-CG55] Ocean Floor Geoscience

[SCG55-P14] Completion of physical properties data of IODP Site C0011, C0012 and evaluation of structure model of the Nankai Trough off the Kumano basin by using synthetic seismogram method

*Korai Ryusei¹, Tetsuro Hirono¹, Jin-Oh Park² (1.Osaka Metropolitan Unversity, 2.Atmosphere and Ocean Research Institute, The University of Tokyo)

Keywords:Ocean drilling, Nankai Trough, Synthetic seismogram

For investigation of the process and mechanism of subduction earthquakes, the structures of accretionary prism, trench, and incoming oceanic crust have been evaluated by using seismic reflection method and deep-sea drilling. Comprehensive analysis using seismic reflection, borehole logging, and core sample data is crucial for understanding their structures. Drilling programs were often performed by Ocean Drilling Program and International Ocean Discovery Program and core sample were continuously collected into the depth. However, there was a lack of the sample owing to technical problems and/or research plan, so that some data have been absent. Here, in this study, we reconstructed the complete depth profile of physical properties such as porosity, density, and P-wave velocity, and produced the reflection coefficient profile from the logging and core-based data at IODP Sites C0011 and C0012 in the Nankai Trough margin. First, we obtained some regression equations among the physical properties in depth and compensated the complete depth profile by applying the regression equation onto the data gap in depth range. By comparing depth profile of the physical properties data and IFREE 3-D seismic reflection data by JAMSTEC in 2006, a good consistency between them was confirmed. Moreover, some narrow zones of unidentified rocks (c.a. 5 m thick) were detected. Therefore, a comprehensive analysis using not only seismic reflection profile but also logging and core-based data would be useful for revealing the detailed crustal structure.