A systematic analysis of basin effects on surface ground motion

“Basin effects” refers to trapped and reverberating earthquake waves in soft sedimentary deposits overlying convex depressions of the basement bedrock, which significantly alter frequency content, amplitude, duration seismic waves. This has played an important role on shaking intensity past earthquakes such as Mw 8.0 1985 Michoa'can, Mexico, 6.9 1995 Kobe, Japan, 7.8 2015 Gorkha, Nepal. Although phenomenon been understood addressed literature, it not fully incorporated hazard analysis, Ground Motion Prediction Equations (GMPE). In this study, we perform extensive parametric study characteristics surface ground motion associated with basin effects using finite element simulations. We use elastic medium subjected vertically propagating SV plane utilize idealized shapes examine geometry material properties. specifically four dimensionless parameters, width-to-depth (aspect) ratio, rock-to-soil contrast, a that quantifies depth relative dominant incident wavelength, distance quantifying edges wavelength. Our results show can be reasonably characterized at least three independent each resultant motion. To demonstrate application dimensional analysis applied here, investigate response Kathmandu Valley during Gorkha Earthquake Nepal soil simplified model capture notable suggests studies provide useful insights, relevant parameterization GMPEs design code provisions.