Evidence for Deep, Wide Low Velocity Bottom to M1

XZ slice through the Final 3D model at y=0 cuts Magma Body M1.
Note that a wide region of low velocities extend deep into the crust (i.e. depths of 6-8 km below sea level).

These record section showing actual seismic data (black wiggles), picks (thin curves) and model predictions (bold pink curves) were chosen for a source/receiver geometery that has rays that rays that pass through the lower par of M1. Note that the traveltimes predicted from the Draped-1D model (left record section) are systematically early. The lover velocities in the lower crust of the the Final 3D model (right record section) does a better job at predicting the observed arrival times.