Mapping NEHRP VS30 site classes

Earthquake Spectra
By: , and 



Site-amplification potential in a 140-km2 area on the eastern shore of San Francisco Bay, California, was mapped with data from 210 seismic cone penetration test (SCPT) soundings. NEHRP VS30 values were computed on a 50-m grid by both taking into account the thickness and using mean values of locally measured shear-wave velocities of shallow geologic units. The resulting map of NEHRP VS30 site classes differs from other published maps that (1) do not include unit thickness and (2) are based on regional compilations of velocity. Although much of the area in the new map is now classified as NEHRP Site Class D, the velocities of the geologic deposits within this area are either near the upper or lower VS30 boundary of Class D. If maps of NEHRP site classes are to be based on geologic maps, velocity distributions of geologic units may need to be considered in the definition of VS30 boundaries of NEHRP site classes. ?? 2005, Earthquake Engineering Research Institute.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Mapping NEHRP VS30 site classes
Series title Earthquake Spectra
DOI 10.1193/1.1895726
Volume 21
Issue 2
Year Published 2005
Language English
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Earthquake Spectra
First page 353
Last page 370
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