In this study we simulate and analyze ground-motion-acceleration time history recorded during the earthquake in a zone between Ferndale and Eureka, and Humboldt Bay. The earthquake was very well recorded in a geotechnical array located in the Humboldt Bay soft sediments. The ground- motion acceleration recorded by the array’s instruments at several depths provided a good opportunity for testing numerical techniques and empirical models of the nonlinear seismic response of soils for input motion with moderate amplitude. A large part of our investigation is focused on modeling the observed nonlinear response of soft sedimentary layers during the earthquake and its empirical representation in the broadband simulation methodology used here. The scope of the presented work was twofold. First, test the performance of a broadband ground-motion simulation technique. Second, evaluate the implication of the nonlinear response of shallow sediments on ground motion recorded at the Humboldt Bay geotechnical array. Our study also provides insight into the composition of the wave field during the earthquake and an improved understanding of how the strong ground motion is affected by the 3D structure in the Ferndale–Eureka, California area, and nonlinear response of shallow sedimentary layers in Humboldt Bay.
