Vs30-κ Relationship Implied By Ground Motion Models?

Abstract eng:
For deep soil profiles, measurement of the in-situ dynamic soil properties particularly damping is not practical. While the shear-wave velocity can be obtained from surface measurement or other existing deep geophysical measurements, the soil or rock material damping is often assumed for the deep layers. Seismologists have characterized the high-frequency attenuation of very low intensity recorded ground motions using the site attenuation parameter (κ 0 ) as proposed by Anderson and Hough (1984). For 1D wave propagation, the κ 0 is related to characteristics of the site profile, specifically the wave travel time (i.e., shear-wave velocity) and the small-strain damping, and can be used to constrain the damping in the site profile. By constraining the damping with κ 0 , the uncertainty is reduced and the confidence in the results is increased. However, developing a site-specific estimate of κ 0 is not feasible for sites without recorded broadband ground motions. Instead, κ 0 may be estimated using published V s30 - κ 0 relationships. This paper examines the V s30 - κ 0 relationships implicit in several modern ground motion models (GMMs). The comparison provides insight how studies targeted on assessment of the V s30 -κ 0 relationship compare with development GMMs that do not explicitly consider the V s30 -κ 0 relationship. The results show that GMMs generally consistent with published V s30 - κ 0 scaling relationships. Additional comparisons indicate that nonlinearity is not influential to the calculated κ except for V s30 of 200 m/s the lowest V s30 value considered in this study.

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