Stochastic model of bedrock earthquake motion and determination of its parameters

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Two-dimensional imaging of soil–bedrock interface by short-array beamforming technique

The depth to soil–bedrock interface, which is one of the major parameters in the site response analysis, has been often investigated by surface-wave tests. The round-robin tests for a surface-wave method in Korea revealed that a long measurement array in surface-wave tests is not appropriate in locating soil–bedrock interface. In this paper, for the improved profiling of depth to soil–bedrock interface in 2-D image, short measurement array was introduced for the beamforming technique, which is a robust array processing technique adopted in a long-array format for stiffness profiling. Numerical simulation and field applications of the short-array beamforming technique indicate that the method is valid even for surface wave propagation with mode-related complexity. Depth to soil–bedrock interface and shear-wave velocity profiles determined by the short-array beamforming technique were in good agreement with layer stratifications of boring logs, resistivity map, shear-wave velocity profiles of downhole tests and CAP-SASW tests.     

Simulation of near-fault bedrock strong ground-motion field by explicit finite element method

Based on presumed active fault and corresponding model, this paper predicted the near-fault ground motion filed of a scenario earthquake （Mw=6 3/4 ） in an active fault by the explicit finite element method in combination with the source time function with improved transmitting artificial boundary and with high-frequency vibration contained. The results indicate that the improved artificial boundary is stable in numerical computation and the predicted strong ground motion has a consistent characteristic with the observed motion.     

How does anisotropy in bedrock river granitic outcrops influence pothole genesis and development?

Pothole formation and development may be influenced by joint sets and other heterogeneities within bedrock, as well as by hydraulics. Previous research indicates that most potholes found in rivers of the mountainous Spanish Central System exhibit preferred orientations associated with dominant joints and correlate more strongly with variations in substrate resistance than with hydraulics. Weathering and erosion weaken rock surfaces, which leads to decreased mechanical resistance. We start from the hypothesis that different mechanisms of pothole formation may create around the pothole a distinctive signature in terms of ultrasound pulse velocity and surface hardness. We develop a conceptual model and test it using potholes for which we know the mechanism of formation, demonstrating that the spatial and statistical distributions of dynamical mechanical properties and surface hardness of a pothole may provide insight into its genesis. Copyright © 2016 John Wiley & Sons, Ltd.     

Study on the rupture characteristics of the overlaying soil with soft interlayer due to fault bedrock dislocation

Introduction A sudden rupture of fault in the crust induces intensive earthquake, and brings about the overlaying soil moving and cracking, and the Earth′s surface deforming and rupturing as well. When it crosses the foundations of buildings and the underground structures, the rupture close to the Earth′s surface or surface fault would lead to direct destruction to these structures. The study on this problem has been paid more attention in recent years. From Kobe Earthquake, Izimit Earthq…