| dc.description.abstract | The threat from earthquakes and tsunamis on human life is immense. To conduct threat assessment and mitigate damage, the scientific community strives to generate physics-based models that accurately portray natural fault systems. Realistic models require better numerical description of deformation processes and mechanisms with appropriate initial and boundary conditions. Mechanical properties, such as elastic moduli and fracture strength, are important parameters in these models; however, it is difficult to accurately estimate these properties at depth. This study aims to document the elastic moduli, fracture strength, and acoustic velocities through laboratory experiments on rock samples collected from the ancient Shimanto accretionary complex and the subducting oceanic plate at the Nankai Trough offshore Japan. All the tested samples including basalt, Nobeoka mélange, Shimanto mélange, white sandstone, gray sandstone, and red shale exhibit an increase in Young's modulus and Poisson's ratio with increasing pressure. The triaxial deformation experiments exhibit that the white sandstone deforms brittle at effective pressure of 5-80 MPa, whereas the basalt deforms brittle at 5 and 10 MPa and ductile at 20 MPa. P-wave and S- wave velocities for the white sandstone and basalt range from 3.70-5.41 and 2.43-3.33 km/s. Based on the experiment results, the simple two layer models with various lithologies at different stress conditions were constructed to estimate the reflection coefficient at the boundary. 18 scenarios out of 64 scenarios considered result in similar reflection coefficient values observed along the plate boundary in the Nankai Trough. | en |
