(a) Topographic map with shaded relief of southern California showing the extent of our 3-D Southern California model. The major late Quaternary faults are shown.
(b) Compressional-wave speed variations along two cross sections AA' and BB'. Cross section AA' runs from the Coast Ranges through the Ventura and Los Angeles basins to the Peninsular Ranges.
Notice the significant 3-D wave-speed variations, and in particular the very low wave-speed sedimentary basins. Also notice the shallow Moho (top of the dark blue region) underneath the Los Angeles basin. Cross section BB' runs from Death Valley through the Mojave and San Gabriel Mountains to the Los Angeles basin. Note again the low wave-speeds underneath Los Angeles and the shallow Moho under the continental borderland.
This cross section also highlights the substantial topography and bathymetry (exaggerated 5 times) that is incorporated in the 3-D model.
[ download Simulations
of Ground Motion in the LA Basin paper (PDF, 5.6MB) ]