  We show reflectivity cross-sections for the San Gabriel, Chino, and San
Bernardino basins north of Los Angeles, California determined from
autocorrelations of ambient noise and teleseismic earthquake waves. These
basins are thought to channel the seismic energy from earthquakes on the San
Andreas Fault to Los Angeles and a more accurate model of their depth is
important for hazard mitigation. We use the causal side of the autocorrelation
function to determine the zero-offset reflection response. To minimize the
smoothing effect of the source time function, we remove the common mode from
the autocorrelation in order to reveal the zero-offset reflection response. We
apply this to 10 temporary nodal lines consisting of a total of 758 geophones
with an intraline spacing of 250-300 m. We also show that the autocorrelation
function from teleseismic events can provide illumination of subsurface that is
consistent with ambient noise. Both autocorrelation results compare favorably
to receiver functions.
