4.2 Synthetic Modeling Results
Since we were only modeling the features at slab depth and only
considering the upgoing Ps conversion, we calculated correlation
coefficients of the predicted and the observed waveforms from 2 s after
P arrival to 10 seconds after P arrival. Model 1 (Fig. 3a) produced the
worst fitting synthetics of all three models (average correlation
coefficient of -0.06). Model 2 (Fig. 3b) which consisted of a
featureless upper crust and an 8 km-thick oceanic crust is better fit
compared to the first model (average correlation coefficient of 0.45).
Model 3 (Fig. 3c), the simple two-layer model with an increase in
velocity at the slab Moho depth is the best fitting model with an
average correlation coefficient of 0.53. The results suggest that the
Vp, Vs and density above the slab Moho must be similar to obtain optimal
fit to the observed data. In other words, introducing additional
features in the model above the Moho, even an oceanic crust, creates
synthetics that poorly match the observational data.