Ground Motion Modeling in Complex Structures

This is the 2nd subproject of the „ENSI – SED-Erdbebenforschung zu Schweizer Kernanlagen“ project.

Realistic modeling of earthquake ground motions can be achieved only if the causative fault and the medium where waves propagate are described accurately. To efficiently simulate high-frequency earthquake scenario in Switzerland, we develop a hybrid broadband simulation technique combining state-of-the-art rupture models along irregular fault surfaces and wave propagation in complex heterogeneous media taking into account station-specific scattering parameters. Significant efforts are made to extend the validity of our technique to model ground motion at depth for possible applications at underground repositories. A thorough validation and calibration of sensitive parameters is based on Japanese and Swiss datasets. Along with source and path effects, near-surface site conditions represent an important factor controlling ground motions since soft sediments can significantly amplify the shaking observed during an earthquake. Depending on the level of input ground motion, liquefiable soils have the potential to generate excess water pressure resulting in high-frequency acceleration pulses. Advanced constitutive models of liquefiable soils require the knowledge of so-called dilatancy parameters that describe the potential to generate excess water pressure. These parameters can be determined from field observations by analyzing cone penetration test (CPT) measurements. Accurate modeling of liquefiable soils subject to high-amplitude Mach waves is essential to explore the physical limits of ground motion.