This method takes a velocity model and creates a vector containing
slowness-depth layers that, hopefully, adequately sample both
slowness and depth so that the travel time as a function of
distance can be reconstructed from the theta function.
Finds the index of the slowness layer that contains the given depth
Note that if the depth is a layer boundary, it returns the shallower
of the two or possibly more (since total reflections are zero
thickness layers) layers.
Finds the index of the slowness layer that contains the given depth
Note that if the depth is a layer boundary, it returns the deeper
of the two or possibly more (since total reflections are zero
thickness layers) layers.
TauP_Create - Re-implementation of the seismic travel time calculation
method described in "The Computation of Seismic Travel Times"
by Buland and Chapman, BSSA vol.