This dataset represents simplified geologic units that have been correlated to the time-averaged seismic shear-wave velocity in the upper 30 meters of the earth’s surface (Vs30). The geologic units were compiled from published maps that range in scale from 1:250,000 to 1:24,000, along with a system for subdividing younger alluvium based on surface slope. More information can be obtained from the associated article published in the Bulletin of the Seismological Society of America: Wills, C.J., Gutierrez, C.I., Perez, F.G., and Branum, D.B., 2015, A next-generation Vs30 map for California based on geology and topography: Bulletin of the Seismological Society of America.
