3.3 1-D Synthetic Modeling
To aid in our interpretation, we produced synthetic receiver functions
(assuming a ray parameter of 0.05 s/km) that tested three simple
velocity-density models of the structure below Kodiak Island. Our
primary goal was to evaluate resolution of hypothetical structures near
the top of the subducting oceanic crust. To better account for the RF
variability across the profile, we selected groups of RFs from three
different sections (6 km bins, centered at 10, 22 and 32 km distance
along the profile) which showed good signal-to-noise ratios (Fig. 2c)
and linearly stacked them. We then used the position of the slab Moho Ps
arrival on the resultant stacked traces to help with the construction of
the models (Figs. 3a-c).
Model 1 (Table 1; Fig. 3a) was based on the Kim et al. (2014) Kenai
Peninsula model beneath the Kenai asperity. The model consists of a
featureless upper crust, a 3 km-thick LVZ at the plate interface and an
8 km-thick oceanic crust. For model 2 (Table 1; Fig. 3b), we removed the
3-km-thick LVZ and calculated synthetics using just the featureless
upper crust and the 8 km-thick oceanic crust. Model 3 (Table 1; Fig. 3c)
is a simple two-layer model with an increase in velocity at the slab
Moho depth.