Investigating the effects of structural parameters on seismic aggravation of two-dimensional sedimentary valleys

Abstract

The valley-induced ground motion amplification has been well-documented and validated in previous studies, however, it remains challenging to fully integrate them into ground motion models, seismic hazard assessment, and engineering practice. In this paper, we first investigate the 2D seismic response in the Mygdonian basin, Greece, and compare the numerical results with comparable studies to validate the feasibility of our numerical toolbox in quantifying ground motion aggravation. In order to orientate towards more generally applicable conclusions rather than a site-specific, 32 idealized three-layered sediment-filled trapezoidal valleys are constructed with reference to the geological structure of the Mygdonian basin, aiming to explore the sensitivity of their additional effects attributes to the subsurface structure parameters of the valley. The half-width of the valley surface is divided into three subregions according to the wave propagation path, similar to the concept of seismic microzonation. The multivariate analysis reveals that the seismic response of each sub-region has differential or even diametrically opposite sensitivity to these structural parameters. The aggravation factor of the valley edge region shows a significant tendency to decrease with increasing edge angle, but poor sensitivity to the shape factor. On the contrary, the aggravation factor of the central region is positively correlated with the shape factor, but largely independent of the valley edge angle. Furthermore, we performed a quantitative statistical analysis and gave a simple correspondence between the seismic aggravation factor and structural parameters for different period intervals, which is an acceptable quantitative scheme from an engineering point of view.