disba 0.3.0

Features

Forward modeling:

• Compute Rayleigh-wave phase or group dispersion curves using Dunkin’s matrix or fast delta matrix algorithms,

• Compute Love-wave phase or group dispersion curves using Thomson-Haskell method,

• Compute Rayleigh-wave ellipticity.

Eigenfunctions and sensitivity kernels:

• Compute Rayleigh- and Love- wave eigenfunctions,

• Compute Rayleigh- and Love- wave phase or group sensitivity kernels with respect to layer thickness, P- and S- wave velocities, and density.

Installation

The recommended way to install disba and all its dependencies is through the Python Package Index:

pip install disba --user

Otherwise, clone and extract the package, then run from the package location:

pip install . --user

Usage

The following example computes the Rayleigh- and Love- wave phase velocity dispersion curves for the 3 first modes.

import numpy
from disba import PhaseDispersion

# Velocity model
# thickness, Vp, Vs, density
# km, km/s, km/s, g/cm3
velocity_model = numpy.array([
   [10.0, 7.00, 3.50, 2.00],
   [10.0, 6.80, 3.40, 2.00],
   [10.0, 7.00, 3.50, 2.00],
   [10.0, 7.60, 3.80, 2.00],
   [10.0, 8.40, 4.20, 2.00],
   [10.0, 9.00, 4.50, 2.00],
   [10.0, 9.40, 4.70, 2.00],
   [10.0, 9.60, 4.80, 2.00],
   [10.0, 9.50, 4.75, 2.00],
])

# Periods must be sorted starting with low periods
t = numpy.logspace(0.0, 3.0, 100)

# Compute the 3 first Rayleigh- and Love- wave modal dispersioncurves
# Fundamental mode corresponds to mode 0
pd = PhaseDispersion(*velocity_model.T)
cpr = [pd(t, mode=i, wave="rayleigh") for i in range(3)]
cpl = [pd(t, mode=i, wave="love") for i in range(3)]

# pd returns a namedtuple (period, velocity, mode, wave, type)

Likewise, GroupDispersion can be used for group velocity.

disba’s API is consistent across all its classes which are initialized and called in the same fashion. Thus, eigenfunctions are calculated as follow:

from disba import EigenFunction

eigf = EigenFunction(*velocity_model.T)
eigr = eigf(20.0, mode=0, wave="rayleigh")
eigl = eigf(20.0, mode=0, wave="love")

# eigf returns a namedtuple
#  - (depth, ur, uz, tz, tr, period, mode) for Rayleigh-wave
#  - (depth, uu, tt, period, mode) for Love-wave

And sensitivity kernels:

from disba import PhaseSensitivity

ps = PhaseSensitivity(*velocity_model.T)
parameters = ["thickness", "velocity_p", "velocity_s", "density"]
skr = [ps(20.0, mode=0, wave="rayleigh", parameter=parameter) for parameter in parameters]
skl = [ps(20.0, mode=0, wave="love", parameter=parameter) for parameter in parameters]

# ps returns a namedtuple (depth, kernel, period, velocity, mode,wave, type, parameter)