Ground motion amplification due to underground cavities subjected to incident SV and P in-plane waves

When a fault crashes, seismic body waves travel away from the source to the ground surface. Seismic wave characteristics change due to source, path and site effects. Site effects consist of surface and subsurface irregularities, such as cavities that can affect the properties of seismic waves. Therefore, in this study, the effects of underground cavities on surface ground motion amplification are investigated for circular and elliptical shapes. Underground cavities are subjected to the vertically propagating SV and P in-plane waves. The effects of dimensionless frequency, depth of cavity, geometry of cavity and also presence of the second cavity are studied in this research. Results show that increasing of dimensionless frequency causes increase in ground motion amplification for both cases of incident SV and P waves. It is also concluded that depth and geometry of cavity can cause very important effects on the ground seismic motion. Presence of second cavity can also aggravate the ground surface seismic motion in addition to the first cavity. (C) 2015 Sharif University of Technology. All rights reserved.