SOME OBSERVATIONS OF MODELLING OF WAVE MOTION IN LAYER-BASED ELASTIC MEDIA

This paper aims to provide some observations on the merits and disadvantages of Cartesian and cylindrical co-ordinate representations (CaCR and CyCR) in modelling of wave propagation in layer-based elastic media and its engineering applications. The observations focus on (1) difference and consistency in solution procedure for wave motion in layer-based elastic media, (2) identification of its fundamental properties, (3) computational efficiency in relation to wave motion synthetics/simulation, and (4) basis for the applications to stochastic wave motion modelling associated with uncertainty in complex medium structure as well as source mechanism. Specifically, modelling of earthquake wave motion in a layer-based elastic half-space is used for illustration. As a foundation for the investigation, CaCR and CyCR for three-dimensional (3-D) wave motion are first constructed in a concise and consistent form. Consequently, some basic characteristics of 3-D wave motion in layered media (e.g., various surface waves) can then be identified in a unified form for the aforementioned different co-ordinate representations. More importantly, the succinct representations for 3-D wave motion provide a stepping stone for further study on wave motion modelling with uncertainty in the Earth medium and source mechanism. These and the other pertinent issues will be investigated in this study from the viewpoint of systematic computer code development and computational efficiency, which is substantial to practical engineering applications.