Amplification of Long Period Ground Motion by the Los Angeles Basin
Monday, January 13th, 2014
Empirically derived ground motion amplification in the Los Angeles Basin is presented. Data obtained from 15 separate seismic networks in southern California from events recorded between 1998 and 2009 are used to determine spectral response as a function of both basin depth and period.
The response associated with basin depth, defined by the 1.0 km/s S-wave velocity isosurface, increases monotonically with depth for the horizontal component, and nearly monotonically for the vertical component for each oscillator period. This trend is similar for the 2.5 km/s S-wave velocity isosurface, though less smooth, especially when data is processed in smaller bins (500m). These results show consistency with amplifications derived from synthetic data in earlier studies. Additionally, amplification factors are similar to previous empirical studies, ranging from roughly 3.8 for the vertical component to about 4.2 for the horizontal component.