Near surface shear wave velocity increase trend estimation from dispersion curve and its utilization for H/V curve technique at a sediment filled crater site, São Paulo, Brazil

The parameters shear wave velocity and soft sediment thickness are very important for the site investigation such as engineering application or microzonation. Shear wave velocity has an average velocity increase trend up to the bedrock,This velocity increasing trend can been obtained from the knowledge of two known variable (shear wave velocity at one meter depth β₀ and the velocity increase dependence on depth x ). The velocity at one meter depth β₀ and depth dependence of velocity increase x both these values are obtained from the borehole data which is hardly amiable at each site .We have tried here to utilized MASW data to obtained these two variable ( β₀,x) from best fitting the shear wave apparent velocity values versus depth plot. Later we have utilized the newly suggested H/V based average thickness formula to find out the composite thickness which comprised of arbitrary numbers of sub layers thicknesses of Functionally Graded Material (FGM) over bedrock. We have checked this approach for two theoretical model to test its validity, latter this is applied to seismic ambient noise data recorded at meteorite impact based crater, which is filled by very recent soft sediment. Thickness measurement estimated via this procedure are consistent with the results of other geophysical technique performed at same location.